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OMEGA2000 user`s manual - Calar Alto Astronomical Observatory

1. July Elevation of fields M67 Focus 1h 90 80 NGC 1647 MU Lig Focus 60 m 12h PL Focus 50 Z 17h ra o a Focus i 1 22h m e 30 Soe 20 27 10 e 0 21 00 22 00 23 00 00 00 01 00 02 00 03 00 _ UT o moon October Elevation of fields M67 Focus 1h NGC 1647 Focus 12h Focus 17h Focus 22h LI x bol Lj 19 00 20 00 21 00 22 00 23 00 00 00 01 00 02 00 03 00 04 00 05 00 UT o moon Figure 57 Elevation plots for focus fields July and October 02 12 2008 13 01 132 OMEGA2000 manual doc Appendix 8 Astrometric fields Astrometric data are provided to enable an easy check of the plate scale and a direct determi nation of the image rotation The fields were selected from the M2000 catalogue Rapaport Le Campion et al 2001 These catalogue has a very recent epoch and is complete to V 15 4 5 Therefore many stars are found in each OMEGA2000 pointing We thank the authors for supplying the data on CDROM The tables with the positional information are available on fire35 as an html file under disk a o2K MANUAL Astrometrie FC html For applications where also proper mo tions have to be taken into account the data from the UCAC2 catalogue have to be used These are also provided under the above path as Astrometrie UCAC2 html name RA
2. 149 02 12 2008 13 01 16 Subject index 2MASS catalogue 19 astrometry calibration 19 fields 133 atmosphere important absorber 9 transmission 74 windows 8 background emission sources 9 limited regime 14 subtraction 15 thermal emission 8 bad pixel mask 73 baffles 25 calibration 73 calibration file 80 dark measurement 50 flatfield measurement 50 photometric zero points 143 standard stars 144 camera 20 control 33 catalogue objects 44 CCD 11 centre to corner distortion 15 channel layout 21 clocking rate 20 control electronics 28 conversion factor 21 electrons to counts 21 dark current 18 detector 93 bad pixel mask 18 linearity 18 over exposure 93 reset 11 saturation 11 dewar 26 dithering 16 65 extended objects 68 pattern 65 double buffering 45 field rotation 15 file listing disk 74 tape 74 filters 25 89 02 12 2008 13 01 OMEGA2000 manual doc FITS keywords 97 flat field 17 dome 18 52 exposure times 91 sky 18 focal plane array 11 focus 17 56 fields 125 position 29 GEIRS 31 graphical user interface 30 HgCdTe 11 integration time calculation 14 Login 30 macros 45 100 MIDAS session 42 mosaicing 15 night sky level of 10 object catalogues 44 observations survey 63 OH emission 10 OH emission spectrum 10 OMEGA2000 baffles 25 dewar 26 optics 25 photoelectrons 11 photometry calibration 19 pipeline 76 calibration file 80 examples 87 flow charts 84 pixel size 20 quantum efficiency
3. network Figure 30 Block diagram of the read out electronics 27 02 12 2008 13 01 OMEGA2000 manual doc 7 6 Control electronics As the read out electronics the control electronics is also mounted in racks on the front ring Both are sealed in cooling bozes to carry away the heat produced during the observations The control electronics is in charge of the following tasks e filter wheel movements e deploying the movable baffle e monitoring of various temperatures in the instrument and pressure in the dewar An example of the latter is given below in Figure 31 see also graph on page 34 7 7 Dewar The vacuum dewar of the Omega2000 instrument has a cylindrical shape with an outer diame ter of 600 mm and a length of 1680 mm The HAWAII 2 detector and all other inner parts are cooled by liquid nitrogen to a temperature of about 77 K To reduce the heat load on these components three radiation shields are nested into each other The large dewar entrance win dow is made of fused silica with a diameter of 350 mm and a thickness of 20 7 mm The liquid nitrogen is stored in two vessels that can be filled on the telescope through the up per side of the dewar One of the nitrogen tanks is directly connected to the inner radiation shield and is referred to as the inner vessel in the following Its capacity is about 47 litres The outer vessel with a capacity of about 72 litres is connected to the second shield Both nitro gen ve
4. instrangle type USER syntax instrangle angle Sets angle as the instrument angle for the NSEW orientation For relativ telescope movements the complete correction angle is currently given fratio e g ALFA F25 22 0 angle instrangle Without parameter the actual field of view angle relative to NSEW will be printed counter clockwise The complete cassegrain angle would be casspos actual cass angle cassoff instrangle given fratio angle This value should be written into the FITS headers as CASSPOS itime type USER syntax itime time stdout stderr o ffset sec m ultiple sec Set the integration time time in seconds Without time argument it prints the actual integration time status If the one of the options stdout or stderr is given the status value is additionally printed to the according output stream The options o and m are specifying adjustment and offset val ues which are valid and used until the value s are set back to 0 0 according to the formula used itime m ultiple adjustment o ffset ex o 0 030 adds a constant offset of 0 030 seconds ex m 0 020 adjusts itime to a multiple of 0 020 seconds 50Hz multiple adjusted itime always gt given itime Attention These values can be configured by the staff via the envi ronment variables CAMITIME_MULT and CAM
5. 2 5 set cuts of reduced images to median 2 sigma median 5 sigma flags 0 1 1 save position screen output do not save sky frames do full detector calibration at start display screen output flatfield std cal file use the standard calibration ASCII file to look for the relevant calibration frames Examples o2k online Standard pipeline online mode No parameters needed The function has to be called after the observations have started The image catalog created by the observing utility is used The sky is determined from 5 frames with the fast median mode The superimposed images are written to disk after every 7 image The kappa sum cosmics clipping parameter is set to 10 02 12 2008 13 01 76 OMEGA2000 manual doc o2k pipeline june10 obs 3 2 5 5 0 1 10 2 5 0 1 0 amp disk a o2k cal file cal Reduce the image catalogue junelO obs cat Use 3 images on either side i e a total of 7 images for the sky determination in outlier mode 2 with outlier clipping 5 sigma above the median level Use 5 images for the refer ence sum frame do reduction and summation and save only the final master sum frame Remove cosmics that are above a 10 sigma threshold The cuts for the final frames are set to median 2sigma median 5sigma The mod elled sky will not be saved all calibrations are done at the beginning sup press any screen output Use the ASCII file disk a o2k cal_file cal to read in the paths and names of
6. 2 06 19 m Ga um Stix 28 2 E pap stay 731 57 zs se f ET Name Alpha Delta Eqnx Vmag Comment 4 Figure 40 Telescope control window 39 02 12 2008 13 01 OMEGA2000 manual doc Basic control of the telescope such as moving to an absolute position or offsetting from the current position is done on the telescope control panel The basic information from the tele scope such as airmass UT and current telescope position is also displayed here This GUI panel should start automatically when the GUI is first initialized If not you can call it up from the camera control window in the menu Modules File Menu e SAO map Calls up a separate GUI panel which shows the area of sky where the tele scope is pointing including nearby SAO stars This panel is described in more detail below e Airmass Graphical display of the current airmass and plot of the airmass history for the currently set object e Quit Quits the telescope control panel but not the GUI This module can be restarted from the modules menu on the camera control panel Moving to an absolute position An absolute position can be entered directly in the RA and Dec windows After setting the equinox the position can be sent to the telescope by clicking on the move button Note that the telescope does not actually move only the coordinates are sent To move the telescope you must press the go button on the old telescope controls The RA and Dec windows al
7. FO EH msio always waits for a reponse from motor 02 12 2008 13 01 112 OMEGA2000 manual doc next type USER syntax next t or n filename Sets filename as the default filename This filename is used when no filename is given with the save command Auto numbering A filename with an alpha char at the end basename will automatically be extended with 4 digits where first the current save path is looked up for any files which contain any of the GEIRS extensions with the basename and 4 digits at the end Then the next fr digits count is added to the given basename and used as next filename Option t with or without a filename tells the system that the next save command is not allowed to use the current next default filename but a special testfile name After the next save command the default filename is automatically reactivated also if there was an error or problem with the save command Multiple save orders in a single save command are treated as a single save commang If option t is given without a filename the special name test is used else it uses the given filenam But the testfile filename is not used if the next save command is given with a filename To deactivate the just triggered next special test filename you might either just call next n without filename argument or next n filename where filename will be handled like abov
8. Figure 2 Contributors to the atmospheric absorption in the wavelength range 1 to 6u 0 Cox 2000 Figure 2 shows that water is the principal absorber at near infrared wavelengths between 1 and 6 um with very strong bands centred near 1 1 1 38 1 88 2 7 and beyond 6 um CO is the next most important absorber at these wavelengths with strong bands near 2 0 2 7 and 4 3 um and much weaker absorption near 1 22 1 4 1 6 4 0 4 8 and 5 2 um Other trace gases including CH 2 4 and 3 3 um O 3 3 3 57 and 4 7 um and N20 2 1 2 2 2 47 2 6 2 9 and 4 7 um also produce some extinction at these wavelengths T 9 atmospheric 9 10 emission E GBT T YA E 100 E 4 7 10 2 ese 9 10 Babe o ss Ned sep AA 4 z 10 As 1 10 100 1000 Wavelength um Figure 3 Background emission sources see Cox 2000 OH OH airglow Average OH emission of 15 6 and 13 8 mag arcsec 2 at J and H respectively GBT Ground based telescope thermal emission optimized for the thermal infrared and approximated as a 273 K blackbody with e 0 02 Emission from the Earth s atmosphere at 1 5 25 um is shown ZSL Zodiacal scattered light at the ecliptic pole approximated as a 5 800 K blackbody with e 3 x 10 14 ZE Zodiacal emission from interplanetary dust at the ecliptic pole approximated as a 275 K blackbody with s 7 1 x 10 8 Based on observations from the Infrared Astronomical Satellite IRAS GBE Galactic background emission f
9. To implement this feature the macros should be written as in the example above with a sync tele after the telescope offset and save commands The GUI will then only wait until the telescope move is completed before starting the next read the save command may still be in progress When observing in the K band the increase in efficiency of observing the fraction of time spent actually integrating on source is significant With 3 second integrations 11 repeats and saving images 2 through 11 as an integrated image effi ciency jumps from 33 to 40 Using macro commands in a shell script or MIDAS prg All of the above macro commands can be used in shell scripts by preceding them with the string cmd 02000 Example for the use of macro commands a MIDAS procedure set format I1 F6 1 set image parameters cmd 02000 crep crep cmd 02000 itime itime S cmd 02000 sync S cmd 02000 filter P4 S cmd 02000 sync 02 12 2008 13 01 46 OMEGA2000 manual doc 11 Trouble shooting From time to time it can happen that a process hangs Mostly you can simply kill the hanging process Some commands are prepared for this e kill read terminates a read command e kill telescope terminates any command to the telescope e kill wheel terminates any command for the filter wheels Type these commands in the interpreter window where you have started the GUI If you have any trouble with one of the instruments please report to Peter Bizenberger
10. chopper mode CHOPP A 0 000000 chopper angle degrees CHOPP P DC A chopper position in DC mode EMP A 0 000000 sensor A K EMP B 0 000000 sensor B K PRESS1 6 480e 08 mbar 2007 09 27 03 05 pressurel PRESS2 0 000e 00 mbar 2007 09 27 03 05 not used EMPMON1 81 306999 K 2007 09 27 03 05 filter box EMPMON2 81 156998 K 2007 09 27 03 05 motor EMPMON3 475 000000 K 2007 09 27 03 05 optics EMPMON4 75 705002 K 2007 09 27 03 05 fanout EMPMON5 75 622002 K 2007 09 27 03 05 detector plate EMPMON6 75 688004 K 2007 09 27 03 05 cold plate EMPMON7 36 619999 K 2007 09 27 03 05 inner shield EMPMON8 77 925003 K 2007 09 27 03 05 outer shield ROTSTAT offline rotator table rottab ROT TK 0 rottab tk ROT TRM O rottab trmode ROT RK O rottab rk ROT RTA 0 000000 rottab rtangle ROT RVA 0 000000 rottab rvangle ROT CLM 0 rottab clmode SOFTWARE GEIRS Vers 377 sgeneric x04 Jun 14 2005 12 58 51 COMMENT your comment END 99 02 12 2008 13 01 OMEGA2000 manual doc Appendix 6 Complete list of macros The following macro commands are available in GEIRS some are not applicable to OMEGA2000 abort alarm aperture area autosave backup batching buffers cassoff casspos cd chopper clobber coadds continue controls counter cplats crep ctime ctype delay dir display engstatus engwindow exit f
11. or next filename where filename will be handled like abov Without any argument the command returns the next default and next test filename where the one which would be used at the next save command when save is given without a filename argument is marked as next The test filename shows you also the starting string of the saved files which are not queued to automatic storing to tape etc object type USER syntax object text Sets text as object in the FITS header syntax object Prints the actual object observer type USER syntax observer name Sets name as observer in the FITS header This name is used as password for the privileged commands syntax observer Prints the actual observer s name 113 02 12 2008 13 01 OMEGA2000 manual doc optics type USER syntax optics wheel position Moves camera optics wheel Without parameter all possible positions and the actual position are printed OmegaCass only optics is a background process and should have a sync after it when used in a macro pause type USER syntax pause macro Stops any command execution only continue or kill is executed With option macro pause will only get active if a macro is found running Commands macro will be continued by entering the continue command or may be aborted by abort pipe type
12. several images by appropriate xy shifting internal The keyword file_path defined as the first keyword in the PRG contains the path information for the pipeline auxiliary files In online mode the pipeline searches this path for all relevant information Functionality The dither pattern for details see Section Survey observations is applied simultaneously to the object and the sky observations The sky field is specified by a distance from the object and by a direction If the direction is set to ALL 8 different sky positions are used the four shown below plus the 4 corner positions 02 12 2008 13 01 70 OMEGA2000 manual doc Extended Object Figure 44 Sky positions for observations of extended objects Comments e When the observing macro is started the telescope has to point at the object e The observing macro prepares the online pipeline data reduction The name and path of the image catalogue and the integration time are stored in auxiliary files which can be accessed by the pipeline The image catalogue is updated with the name and path of the latest image after every integration e With each new telescope movement the time the offset and the dither number are written into a log file tel pos datej log in the current directory The date in the file name is the date and time the MIDAS procedure was started 71 02 12 2008 13 01 OMEGA2000 manual doc 13 7 Measuring the seeing o2k seeing zoom default n
13. userstatus type ENG 02 12 2008 13 01 127 OMEGA2000 manual doc syntax user Prints user status astronomer engineering superuser verbose type US ER F E syntax verbose on off yes no If you set verbos to the screen while executing a macro the system will print e g every command yes you will get more output and the line number so you always know which macro line is executed Default is Wi yes thout a parameter verbose prints status of the verbose flag version type US ER F E syntax version Prints version string of the Software wheel type USER syntax wheel position name or r elative offsetsteps wheel rdb wheel dialog on off wheel focus on off new Move wheel number to named position or returns information wheel is the logical wheel order from 0 n as shown by the answer of the command wheel itself example wheel returns overview of all wheels reads and shows current wheel positions wheel 2 returns information about wheel2 wheel 2 wollaston45 moves to wollaston45 element wheel 2 rel 25 moves wheel2 25 steps backwards wheel dialog off switches GUI warnings errors w w w heel heel heel heel heel is a background process and should have a sync after when used in a macro rdb Focus Focus Focus wheel
14. voltage as a function of time sese 12 Figure 7 Read out mode reset read ose aee et D ee a ceased em 12 Figure 8 Read out mode Double correlated read see 12 Figure 9 Read out mode multiple end point sampling ssssssssssesese 13 Figure 10 Readout mode sample up the ramp ssssssssseseeeeeeeenenen 13 Figure 11 Signal to noise ratio as a function of integration time sse 14 Figure 12 Field orientation in a mosaic of images taken with a parallactic mount of the ielesCODB cenas e netz i uoa e da aia van Aue dep a OG Sats diront ue eer e 15 Figure 13 Determination of sky background from dithered science frames 16 Figure 14 OMEGA2000 on the frontring cut away CAD draing sess 20 Figure 15 Quantum efficiency of a HAWAII 2 detector as a function of wavelength left The ESO data are from a different detector Finger 2002 the Rockwell data are from a detector dotted similarly to FPA 77 which unfortunately was not measured The adopted DQE curve for FPA 77 is shown In Ted se ecce rere Sette veia tate e bn t neret 20 Figure 16 Quadrant and channel layout for the HAWAII 2 detector left and H band twilight flat right The cut values for the flat are 130 black to 340 red 21 Figure 17 The scheme of the reset level read reset read
15. will take effect only after the next major loop e g the next focus setting in a focus test or the next dither position in case of an observing sequence Disk The green portion of the bar indicates the fraction of the selected disk which is still available If you are taking lots of data keep an eye on this The GUI also issues an audible warning when the disk is getting close to full assuming you have not turned off the sounds 02 12 2008 13 01 36 OMEGA2000 manual doc 9 3 2 Real time Display 5 Ta aei Radius min max Br ia moan devi 366 4 3968 ew fix 18 sts First ef taste Imm Jereo a Figure 39 Real time display The display tool shows one frame of the current set of data Some on line data processing techniques are available These techniques affect only the displayed data only the raw data is saved to disk In addition there are various helpful options to move the telescope to certain positions File Menu selects the basic display size e 256 changes display window to 256 screen pixels square The full Omega2000 image is displayed binned 8x8 Note that in general you will not see your objects in highly binned mode as they most often will happen to fall between the displayed pixels 37 02 12 2008 13 01 e 512 changes display window to 512 screen pixels square e 1024 changes display window to 1024 screen pixels square e 2048 changes display window to 2048 screen pixels square Th
16. 20 Rayleigh 10 readout non destructive 11 read out electronics 27 read out mode double correlated read 12 implemented 21 line interlaced 23 mulitple end point sampling 13 sampling up the ramp 13 150 OMEGA2000 manual doc Read out mode 12 read put mode double buffering 45 real time display 37 saving data 43 seeing 72 signal to noise ratio 14 151 sky observation 71 tape copy 94 telescope 29 control 39 coordinate zero point 29 tip tilt 29 61 02 12 2008 13 01 UKIRT Faint Standard Stars K BAND FINDING CHARTS e L1 gt M gt i o BS e e gt FS 16 x o edd gt OE VIA Prepared by David Thompson Max Planck Institut f r Astronomie Heidelberg Germany Introduction The pointing on modern telescopes is typically good enough to place standard stars some where near the middle of the imaging arrays so one can point and shoot and be reasonably assured that the standard will be observed I still prefer to verify fields as I take data which was the primary motivation in producing these finding charts The construction of the prime focus infrared camera for the Calar Alto 3 5m telescope added some additional incen tive as other existing flux standards e g from Elias et al 1982 AJ 87 1029 are too bright for this camera Finally enough copies of my loose leaf stack of finding charts had been requested that it seemed reasonable to produce a more formal compilati
17. 42 OMEGA2000 manual doc 9 5 Taking data The windows introduced thus far are the environment in which one takes data manually in cluding the use of GEIRS macros see Section 10 This is useful for tests or special calibra tions For taking standard calibrations darks flats focus the telescope and dither science frames it is strongly recommended to go to the MIDAS environment and use the procedures described in Section 12 9 5 1 Setting up the camera for an exposure Before you start make sure you have selected the proper paths for your data etc see Figure 36 at upper right You should also set the root name of the files to be stored on disk which is also done in the camera control window The instrument is completely setup in the camera control window Here you select the filter the read out mode and the exposure times to name the most important You should use the filter macro to select your filter This is faster than turning the wheels individually Further more the macro automatically inserts also a blocking filter if necessary 9 5 2 Taking exposures An exposure is taken by pressing the READ button below centre in the camera control win dow Although this exposes the image it is only read into the memory of the instrument computer There you can use it to take a look at it on the real time display measure back ground level seeing etc there If you decide to keep the image you also have to decide on the mode
18. 7 itime 10 1 Use 7 different focus positions centered around 23500 microns with offsets of 200 mi crons The total integration time per image is 10 seconds which consist of 10 co added 1 second exposures The image name in the GUI is used for the filenames e o2k focus foc H 4 24000 200 7 20 2 1 Use the seven images with names foc H0004 fits foc H0010 fits for the focus analysis only The best estimated focus was 24000 microns The integration time is in this instance only used to compute a saturation cutoff for the object selection e o2k focus help 02 12 2008 13 01 56 OMEGA2000 manual doc Shows help text o2k focus prompt Inquires all parameters interactively Parameter explanation External command line parameters Pl P2 P3 P4 P5 P6 57 root Root name of all relevant images The full image name is expected to consist of the root and a 4 digit index e g foc HO001 fits with root foc_H The index P2 must result in unique filenames if new images are taken otherwise existing files will be overwritten It is thus not recommended to specify the root for taking images If no root is specified the current image name in the instrument GUI is used as file name This mode is only possible if new focus test exposures are taken index master Index of the first image i e the image with the lowest focus setting Optional index for master see details below focus estimated focus step size B
19. 9 3 2 A AS o Esp RUN a un geram cadeau t eed 37 9 3 3 Telescope control window essc ea csv ets tee eu eMe Son Lan SE 39 934 SAO Map Wind Wa eo x a iin der as e E M een Wa a 40 9 3 5 Adr Mass WADQOW ias 41 9 3 6 Strip Chart o UII redo Deae sU CAI In toe maa 41 94 The MIDAS ESOO dis 42 SAL OUICEIUOR Ai ha Uk a ea 42 DAD SI A i 42 DAS PP AA oes en EU as 42 9 5 akinb tdi sa neo de sto teu te tated iO a aaa el eae ss d uu 8 43 02 12 2008 13 01 2 OMEGA2000 manual doc 9 5 1 Setting up the camera for an expoSUte iie eter eerie raria da eR AE 43 Dog Tulio CKO SUELOS e o sede deas CGU ate ttem seats as cease tete 43 9 5 3 Image inspection with the real time display ai 43 9 6 Saving datas aseo a E Gina de E E E I tea n o n eons 43 Det Objectedialob ue iced ise eta ouis aee dul a od das tudu utere a a aaea 44 I0 MA A cuu LM LC m M Ce a 45 A t i Etpe 47 12 Observine Strategies did 48 L2 T Minimizing Overhead i ee ete eben tet aec ele dde ebur 48 T3 Observine A O A iua onum te din qoc oh RAN IS 49 I3 C atibratron Se IA aoo DI See pi cet cbr aede 50 13 2 Dome flats oes ses o dieit cse ia rer das Sedo Ata Rer tee CO PRU NEU aS 52 13 2 1 Operating the flatfield latinps iiir mitosis etit eite read ta iran 53 13 3 Taking twilight flats 2 9 not Clana ache ere do Qua S t cett tte a ae 54 3A ROCUS lest E C 56 13 5 Tips Tilt Determination ecosistema putt o me E tee qae i en
20. C ea aaa Ca C C Cu Gu Ca Cu aa aaa aa aaa aa akaka ka kana naa na na nana aa ka kana namana na na nana anakana amana ea 0 17 DA3 0 09 0 24 DAI 0 21 DA SIA IEA ADA AAA AAA AD AD AD ADA AD AD AD Pai ai AD Vai Pai a a ASS J J J J J J J J J J J J J J J J J Finding Charts All of the following images are printed with standard astronomical orientation north is up and east to the left The images are roughly 4 arcminutes square a scale bar of 1 arcminute length provides a reference in each image The UKIRT faint standard star in each image is indicated with tick marks I have thus far been unable to positively identify the fields of FS10 FS11 and FS14 so I would not recommend their use at this time In addition a quick search through SIMBAD revealed that FS24 SA106 1024 was listed as a variable star In the several observations I have of this standard the magnitude appeared to be relatively constant and at the magni tude given in Casali 1992 but one should probably avoid using this star for accurate flux calibrations of infrared data The finding charts are arranged in numerical order by their faint standard number This arrangement should make it easier to find the images quickly This version is missing finding charts for FS18 and F526 I have the data for these fields I just have to reduce it For users of f at C
21. E i B ir gn wa i m 1 e 1 a E u 1 ft 1 1 a gt E a T P RE x k wir zi i a wor T Li LI Lom bea E A E LET m Li Phi y Li a ql o5 c i pa E rf 5 F La a a LJ i i i Lj E at Q no a a r L p i wo oW 4 pi 4 a on ae Bator P H A xd ul i Et SB he L x a V BR E 1 ow a i 3 n E E L D di ET E l 1 x za jJ r E 3 spud Tie ata p Murus ct aa E z ES is 2 i d LI E i WT A E r a iz 4 l 4 E UY ta r 7 n J N 5 j p r E E al L F poem E e LI E E 4 zs T D T im E T aL r q 1 a ra A E s t Pao s E HE i T F 4 1 k 1 x 5 a E 5 F E a A a 4 i r Fa 3 E Li zh a To ai E E Y Lg a F y ta 5 FC Li Y E 1 Figure 55 Focus field at RA 22h 02 12 2008 13 01 130 OMEGA2000 manual doc January Elevation of fields M67 Focus 1h 90 80 NGC 1647 UT 18 00 19 00 20 00 21 00 22 00 23 00 00 00 01 00 02 00 03 00 04 00 05 00 06 April Elevation of fields M67 Focus 1h NGC 1647 Focus 12h Focus 17h Focus 22h 20 00 21 00 22 00 23 00 00 00 01 00 02 00 03 00 04 00 UT i moon Figure 56 Elevation plots for focus fields January and April 131 02 12 2008 13 01 OMEGA2000 manual doc
22. J2000 DEC J2000 2h 2 37 47 80 16 49 31 0 5h 4 49 4 75 13 5 20 0 M67 8 51 21 91 11 49 30 0 13h A 13 16 37 00 17 43 30 0 13h B 13 4 11 90 12 34 30 0 18h 17 41 55 92 14 43 0 0 22h 22 20 20 97 13 18 50 0 We supply finding charts of two types One plots the astrometric reference stars with the brightest stars marked for easy cross reference The second chart is a copy from the red DSS II Both have a side length of about 16 arcmin We also provide elevation plots for four times in the year for optimal selection of the appro priate fields 133 02 12 2008 13 01 OMEGA2000 manual doc Astrometry 2h 16 95 16 90 16 85 e O Lu a 16 80 16 75 16 70 2 640 2 635 2 630 2 625 2 620 RA h x y LI co s e y x Wa 3 E x eo j Al r1 5 x Y x a 2 a 5 gt i z dro E Li k E d a 4 f Figure 58 Astrometry field at RA 2h finding chart for astrometric stars from M2000 02 12 2008 13 01 134 OMEGA2000 manual doc Astrometry 5h 13 21 13 16 13 11 gt o Lu a 13 06 13 01 12 96 4 824 4 819 4 814 4 809 RA h F Die Los gt dh mu E E Na E b a tro 2 4 Ares i SE s oe s a s T 3 o A x m pl PT gt i E b J tos E a aw eu i oh ol T at i 27 a px m 1 dE a E He DU 5 3 acc evt NER re oo me ja a
23. Shut down of the camera software Within a macro it will just terminate macro execution see quit filter type USER syntax filter position Where position is a filter macro defined in HOME info fmacros x These macros define the position of all wheels following means use the default position availabel for lyot stop only means leave this wheel as it is Without parameter filter shows all available filter macros and the actual one filter is a background process and should have a sync after it when used in a macro fits type USER syntax fits Prints the actual FITS header The output to proceed with the next page enter RETURN to abort the output enter q lt RETURN gt 02 12 2008 13 01 106 OMEGA2000 manual doc syntax fits comment text Sets text in the FITS header as COMMENT get type ENG syntax get offset i f d s Prints shared menor page entry offset i integer entry default f float entry d double entry s string entry gui type USER syntax gui x xserver f font starts a graphical user interface GUI for the camera For the description of the otions see help control help type USER syntax help prints the list of commands syntax help command prints information about the specified command syntax descirebes the various parameters and switches type USER normal user command ENG engineering co
24. a 1 02 12 2008 13 01 OMEGA2000 manual doc 14 2 3 Summation of dithered images Cosmics Removal Prepare Summation Find Objects Load Stack zr x i Pixel Column in Statistics Object Positions Wotld Cootdinates Obsetving Position Real Frame Offsets orld Cootdina Normalization Replace Cosmic o by Median Value L Te Leo C4 Snan Tits a Pixel Value 0000000 Sum Stack Images Retetence Frame Final Master Sum ee Cut the Final Master Sum Frame Add the Sum of Stack livages to the Master Sum 02 12 2008 13 01 86 OMEGA2000 manual doc 14 3 Examples of pipeline results 14 3 1 Images taken with o2k dither t Figure 45 Pipeline result for a sparsely populated field This is the sum of 25 exposures in H The single exposure was 3sec 20 exposures were coad ded in memory Thus the total integration time is 25 min The 5o limiting magnitude as de termined from 2MASS stars and the background noise is 20 8 2 aperture seeing 0 9 Note the over corrected background around objects extended more than the dither amplitude This is due to the sky being determined from images of the same field 87 02 12 2008 13 01 OMEGA2000 manual doc 14 3 2 Images taken with o2k sky point Figure 46 Pipeline result for an image of an extended object NGC7331 in the H band For this image 8 exposures of 30sec exposure time 5sec and 6 co adds in memory were used The
25. and the first readout of the frame are not simultaneous i e a slow reset is applied Figure 19 The output signal is obtained by the subtraction of the reset frame from the integrated one which eliminates the reset noise and bias from the signal value Since the whole array must be clocked three times one full frame reset and two readouts of the full frame the efficiency of this readout scheme is only 33 at the minimum integration time Nevertheless it allows to check linearity of the detector and to create a bad pixel map of it If we apply long integration time without IR illumination of the array then a dark current map can also be created Reset Read Integration Read 1 line 1024 line 1 line 1024 line 1 line 1024 line 02 12 2008 13 01 22 OMEGA2000 manual doc Figure 19 The scheme of correlated double sampling reset read read row time Figure 20 Alternate representation of the double correlated read Correlated Double Sampling with Fast Reset The correlated double sampling can also be implemented with the fast reset scheme This means that the reset and the readout of the reset level are carried out simultaneously and fol lowed by the integration and the readout of the integrated video signal Figure 21 The result frame is provided by subtraction of the reset level from the integrated signal Since the whole array is clocked only two times once for the reset with the first readout and once for the
26. ata 100 Appendix 7 Recommended focus fields oooooconncnnocaconcinanonnnconncconocona nono ncon coc no conc connnoo 125 Appendix 8 Astrometric els iS 133 Appendix 9 Photometric zero points oooooccnococonaconnnonnncnnnononoconnnonnnoon nono no enne nentes nennen 143 Appendix 10 Photometric standard StalS ooooonooncinccnoncconncconoconnnonn nono nocononnnn nono ccoo nc cono cnnncnn nos 144 Appendix 11 LINUX PC as A Trial ASA nwa 145 Appendix 12 Basic MIDAS commands ccoooocnococonoconcnonnncnnncconoconn nono nono nocononnnn conan conan cone cnnn conan 146 Appendix lo do il an alos ka abdi 147 Appendix 14 Acronyms USA a adi 148 E 149 POSS UD NO is 150 3 02 12 2008 13 01 OMEGA2000 manual doc Appended UKIRT faint standard stars Dave Thompson 02 12 2008 13 01 4 OMEGA2000 manual doc List of Figures Figure 1 Atmospheric transmission as a function of wavelength in the infrared wavelength range Cox 2000 siia ee oif pei aer ptis e e et oar asda do e aie aden e tu ade 8 Figure 2 Contributors to the atmospheric absorption in the wavelength range 1 to 6u 0 Cox Pim E E E 9 Figure 3 Background emission sources see Cox 2000 sssssssssssessssessesesseessessrssressessrssees 9 Figure 4 Schematic structure of a HgCdTe HAWAID detector see 11 Figure 5 Difference of detector saturation between a CCD and an infrared detector 11 Figure 6 Detector readout
27. de aa 4 P 2 at gt E i pi k E F a 1 Cote c et Vl ae UE i r pa t Is E TR 1 P 3 a T F 1 A E a gt LI is n Ei i ite 5 AE LS ma a I he e YE L Te 3 4 E E E E E T y E a Si iz ia a i 4 i UP D irs erbe a ene d LA a o E T L e d d i a E En n a r A m ow Ta ha E b LI i Li iiou t Ee i 4 y Li L t E n E a z LEA n s m a a a d 1 A Li x 3 u T Figure 51 Focus field at RA Sh NGC 1647 02 12 2008 13 01 126 OMEGA2000 manual doc M67 a J2000 8 51 15 79 6 J2000 11 49 8 1 JI T r i 5 a T3 NL E 3 i a YA y a wi z 1 E T5 i Wa E i Lj j 4 ee a E s E gt i a z amp g L j a a m a P z a a r 2 y 7 Ml a 2 a T Cal m gt Ta E 3 J E hi A Pinal i s i i Aa M rj Ta tw d Li E a eee E re a G ta E 1 F a izi E m P ge UP ie i t wa o EE eta E 3 E P E za gt H ey 5 Q M Pet ti a ES t SUM Lh is 5 A Bi u a r a za dee ee 3 ki s a LI LI rr 2e t t n i J a E E a P ca u y5 As pi o Rege QUU A Pul a ons a j b a n ac 5 Ji m E LT 4 a cog 1 SY EM 5 AE e a E P a 5 a E L e ia hi i A x gt 1 wa a bt L T s gt
28. focus 123 it is re reading the wheel and wheel macro database files This command is only valid for OmegaCass and Omega2000 on off new controls the relative focus adjustment off on new for the selected wheel element combination deactivates the focus correction of all fil CaL wheels for the next wheel filter commands until it is reactivated re activates for the next wheel command t ne focus correction of all filters which are con figured for CHKFOCUS correction in the wheelN instrument configuration files updates the relative focus correction informa tion of the current wheel combination relat ive focus for all filters which are configured via CHKFOCUS correction in the wheelN instrument configuration files but does NOT change the on off state I e it takes the current focus 02 12 2008 13 01 OMEGA2000 manual doc position as being correct for the current filter combination Focus correction is always done relative to the last filter combination which was saved at the last filter correction action Attention Focus settings outside the wheel focus correction automatism does not influence the correct behaviour of the relative focus corrections as long as no combination of wheel filter changes AND manual focus changes are done during the state wheel focus off to switch relative wheel focus correction on when wheel chang
29. for the current position for example when a read command is fin ished The airmass window can be turned off by reselecting the Airmass option in the file menu of the telescope control panel Using the quit option in the xwindows menu will also kill the telescope control panel Alrmass 9 3 6 Strip Chart Window The strip chart is a data base for images taken with the GUI The images are always displayed in a 128 x 128 pixel format To add an image to the strip chart you have to press the button send in the display window The number of displayed images depends of the size of the win dow If you increase the size of the window more images are displayed GENERIC Strip Chart v2 55c UAE aub det vesc 1 419 ie REM A i Mx oe d RUD aM Ld ma 41 02 12 2008 13 01 OMEGA2000 manual doc 9 4 The MIDAS sessions Figure 33 shows the desktops foreseen for the operation of OMEGA2000 Three of the screens are for MIDAS sessions Their purpose is described in the following sections During launch of each of these you will be queried for the current data directory The MIDAS ses sions need to be run in the path where the data are Should you change this path later please then use the change dir path MIDAS command to set the path for the MIDAS session Do not use the UNIX command cd path This will not work However pwd shows the current MIDAS path 9 4 1 Quicklook The green X terminal is the only session which is laun
30. given by the frame readout time and for all readout modes it is order of one second All the modes can be characterized with their efficiency that is the ratio of integration time to a total cycle time required to obtain an image There are several readout modes feasible for OMEGA2000 but some of them are used only for engineering function Reset Level Read The readout of the reset level of the full array has the simplest readout scheme first the com plete frame is reset then read out A line reset is implemented for HAWAII 2 FPA which means that one reset pulse always resets a complete line of pixels and the chip needs 1024 21 02 12 2008 13 01 OMEGA2000 manual doc pulses to reset the full frame while clocking through the horizontal shift register It allows to accomplish the reset readout cycle in two ways either the readout process is preceded by re setting of the complete frame or the whole array is reset and read out simultaneously In the first case the elapsed time between resetting and reading out of the same pixel is equal to the resetting time of the full array The reset readout scheme is faster in the second case where each row is read out immediately after being reset Figure 17 As the video signal sampled after resetting contains the reset noise and reset bias this readout mode has only engineering purpose and is normally not available for observation Reset Read Rest Read pe eu IL one reset pulse for a complete line B
31. has been completely reduced by the photons This process of signal detection storage is the major difference to a CCD where charge is collected in a pixel leading to smear out effects in case of saturation The following figure from the PhD thesis of Martin G Beckett 1995 gives a vivid discrimination between a CCD and an IR FPA Signal Bark CCD Saturated Figure 5 Difference of detector saturation between a CCD and an infrared detector 11 02 12 2008 13 01 OMEGA2000 manual doc 3 2 Read out technigues in general The figures below are a schematic representation of the voltage on an individual pixel as a function of time At the beginning of an exposure the voltage is set to a predetermined value by a reset When the reset switch is opened the voltage will jump to a variable new level the pedestal and then increases linearly with time as charge from photoelectrons and dark current accumulates in the detector This process continues until the detector is reset to the original level at the end of the integration The linear behaviour of most modern detectors spans the range from zero charge to over 9096 of the total capacity A vreset v reset voltage __ per __ gt time Figure 6 Detector readout voltage as a function of time OMEGA2000 supports a number of detector readout modes suitable for various observing situations These modes appear under the lt Readout gt menu
32. have to start with a standard dark current frame for the different flatfields the specified frame used as flatfield i e identical to the specification in the calibration file name with The names including path should not exceed 80 characters gt tifier FLAT exists the given file will be used by the pipeline appropriate flatfield The FILTER names ar xpected to be 10 c y If the name is shorter positions Maximally 100 lines are read in If FLAT is not presen the wg is automatically selected using the FILTER name haracters long followed by blanks have to fill up the remaining VERSION 1 00 12 06 03 Bad Pixel Mask BPM O2K UTIL pipeline CAL bpm part blown fits Dark Current Frame DARK O2K UTIL pipeline CAL dark current fits Flatfield with priority IFLAT O2K UTIL pipeline CAL FLATS H flat best f fits Flatfields for all filters for automatic selection 1234567891 path name J O2K_UTIL pipeline CAL FLATS H_flat_best_J fits H O2K_UTIL pipeline CAL FLATS H_flat_best_H fits K O2K_UTIL pipeline CAL FLATS H_flat_best_K fits K PRIME O2K UTIL pipeline CAL FLATS H flat best Kpr fits NB1237 02K UTIL pipeline CAL FLATS H flat best fits 02 12 2008 13 01 80 OMEGA2000 manual doc 14 1 1 Online Mode Online Reduction Scheme ONLINE DATA REDUCTION SCHEM
33. max of HW windows is given by the roe variable xxx list xlstart and ylstart values has to be 1 size Examples activation control subwin off Any windowing is switched off only full frame subwin on HW and SW windowing with current subwin information will be used subwin on SW SW windowing will be used subwin off HW HW windowing will not be used subwin off HW 1 Dectivate HW window id hwid 1 subwin on SW 2 Activate an deactive SW window swid 2 window structure setting subwin SW 12 1 1 100 100 SW window with wid 12 of size 100 100 from left lower edge 1 1 is appended to the list of SW windows according to unique wid 12 and window definition free space subwin HW 12 1 1 320 10 HW window with wid 12 window structure clearing subwin clear HW Clear all HW windowing definitions subwin clear SW Clear all SW windowing definitions subwin clear Clear all windowing definitions ATTENTION Setting of windows coord does not include activation of any windowing PS Some instrument implementation might apply only Squared HW subwindows taken xsize 2 Other instruments might support only a single HW or even SW window until now MIDI for example implements only HW windowing in y direction Without or with HW or SW or DET as parameters subwin prints the current settings of HW or SW or DET sync type USER syntax sync read
34. modeled sky is saved or not 0 sky is not saved 1 the sky for each input frame is saved with name sky imagenam fits calibration position position where flatfielding and calibration takes place 0 no calibration is done 1 all calibrations bad pixel correction dark current subtraction and flatfield correction are done at the beginning of the reduction process 2 do flatfielding at the end of the single image reduction bad pixel correc tion and dark current subtraction are still done at beginning screen output specification of the amount of screen output 0 screen output is suppressed the feedback is only saved in the log file 1 the pipeline feedback is displayed on the screen LABEL flags P8 calibration frames Specification of the calibration frames The calibration frames flatfield bad pixel mask dark current frame can be specified in 3 different ways 1 no specification default the standard calibration ASCII file is used to ex tract the calibration frames 2 amp path filename an ASCII calibration file is specified A filename is indicated by a preceding 6 e g flatfield amp disk a o2k cal_file cal For the calibra tion file format see below 3 flatfield bad pixel mask dark current frame the calibration frames are di rectly specified If they are nor located in the local directory the path has to be specified LABEL flatfield Note For the dark frame the descriptor ITIME has
35. number 5 take 5 images offsets 0 30 offset telescope between read cycles not exposures by 30 in DEC no offset in RA check check saturation 30000 45000 saturation and monitoring limit time dusk Examples e o2k skyflats dusk H Take 5 time 2 exposures with 20000cts pixel each saved as 5 separate images in disk Offset the telescope between images i e after 5 exposures by 30 in declination only e o2k skyflats dusk H offsets 60 60 Same as above but with offsets RA 60 and DEC 60 e o2k skyflats help Shows help text Parameter explanation External command line parameters P1 ident Identifier for the images to be taken P2 level Desired count level for a single exposure in counts pixel P3 coadds Number of exposures to be taken in a read cycle 02 12 2008 13 01 54 OMEGA2000 manual doc P4 number Number of read cycles to be taken This is also the number of different positions on the sky used for the flatfields P5 offsets RA offset DEC offset Telescope offsets to be executed between read cycles not exposures P6 check Determines whether the exposure level is checked in a test exposure after each read cycle Use no check to suppress checking P7 saturation monitoring limit Saturation level of single exposure and maximum level until which the level monitor ing should be executed P8 time of day dusk or dawn Specifies whether evening or morning flats are
36. of the graph f time start time of the graph y templ temp2 lower upper temperature limit of the graph d where to open the window e g xt28 0 This window will NOT be killed when the software is shut down using the quit command test type ENG syntax test std med var q 4 r nl n2 executes array electronics tests and appends the result to the file chiptest log either in SCAMTMP normally tmp or in current directory std default prints averages and deviations over all pixels in all images of each single channel and the same for the whole image with additional stdv of channels stdv med prints the median of all channels of each single image var prints the median of all pixel averages time direction and the median of all pixel variances time direction r nl n2 use images nl through n2 only e g test var r 2 ELN q use quadrant output only e g test var q 1 this options is only available for var option trigger type USER syntax trigger extern wait intern trigger switches between external HW triggering and internal starting of ROE via SW This option is currently only used in MIDI Options are extern starting read waits on data from ROE endless wait synonym to extern intern read starts also the ROE data directly MIDI uses extern as default where for all other instruments without internal trigger there is only an intern trigger Without argument it just prints current status
37. often as the field size of the channel parameters x pos y pos trlr reset level read holds the reset level and reads the array delay type ENG syntax delay 4 Set delay between two cycles Unit milliseconds MPIA electronics only dir type USER syntax dir filenames Executes ls 1 in current directory The output stops after 1 page to proceed with the next page enter lt RETURN gt to abort the output enter q lt RETURN gt display type USER syntax display c 1 table i x xserver f font p e of colors 4 240 default 100 1 color lookup table gray temp heat default gray i image size 256 512 1024 105 02 12 2008 13 01 OMEGA2000 manual doc default 256 for Magic Max 512 for Omega x where to open the window e g xt28 0 f font family e g lucida p without argument only tries to get private colormap engstatus type syntax ENG engstatus Requests the engineering status from the camera and prints it on the screen After a Re Send Params in the Control Window the returned values of engstatus should be like this Omega MPIA ctype 2 time 0 x 10ms crep 1 delay rt rpc e omega 23 01 1997 17 01 Max Omega IRL not available engwindow type syntax ENG engwin Opens engineering info window exit type ENG syntax exit
38. on after the mode is changed from 32 to 4 channels and vice versa Detector saturation The detector is sensitive towards over exposure and shows an increased dark current fol lowing over exposure Should this accidentally happen e g during taking twilight flats the detector should be read out several times with the blank inserted This is best done in endless mode and the count level being monitored on the online display 93 02 12 2008 13 01 OMEGA2000 manual doc Gain g and readout noise RON per channel for FPA 77 Kovacs 2006 PhD thesis Fitted 1 g g Fitted o g o RON e ADU ADU ADU Quadrant 1 Chan 1 0 2059 4 86 2 1565 50 80 7 1 Chan 2 0 2102 4 76 1 4323 32 48 5 7 Chan 3 0 2166 4 62 3 2364 69 01 8 3 Chan 4 0 2084 4 80 0 2134 4 92 2 2 Chan 5 0 2041 4 90 2 2312 Chan 6 0 2066 4 84 3 8764 90 83 9 5 Chan 7 0 2200 4 54 2 3432 48 40 7 0 Chan 8 0 2082 4 80 5 6544 130 41 11 4 Quadrant 2 Chan 9 0 1883 5 31 1 3214 37 26 6 1 Chan 10 0 1872 5 34 2 4325 Chan 11 0 1957 5 11 3 2784 85 59 9 3 Chan 12 0 1921 5 21 2 4324 65 93 8 1 Chan 13 0 1983 5 04 6 3476 161 45 12 7 Chan 14 0 1946 5 14 1 7654 46 63 6 8 Chan 15 0 1887 5 30 8 5436 239 82 15 5 Chan 16 0 1971 5 07 1 3221 Quadrant 3 Chan 17 0 1942 5 15 4 5435 120 45 11 0 Chan 18 0 1956 5 11 3 4656 90 54 9 5 Chan 19 0 2059 4 86 1 4324 Chan 20 0 2105 4 75 2 4343 54 92 7 4 Chan 21 0 1966 5 09 0 8776 22 71 4 8 Chan 22 0 2043 4 90 2 3243 55 70 7 5 Chan 23 0 202
39. on how to save the data e g as a FITS cube individual images stacked images by opening the SAVE OPTIONS window with a click of the right mouse button onto the save options button Once set you save the data by pressing the SAVE button Due to the double buffering an image may be saved while the next one is already been taken 9 5 3 Image inspection with the real time display The features of the real time display are described in detail in Section 9 3 2 Please note that you do not manipulate the raw data on disk with these operations 9 6 Saving data The data are stored on one of the disks of the instrument computer under the path you have specified under SavePath in the Options Menu of the camera control window You are ad vised to create a path with your name under disk X 0o2k DATA your name where X is b c or d for the data disks Other locations must only be used after permission by observa tory staff The files are stored as FITS files and are not write protected It is strongly recommended to start the DAT Spooler right at the beginning of the run It automatically copies a file to tape immediately after it is written to disk see Appendix 4 on page 95 This way you need not worry about your data being safe The DAT drive is a DDS4 so you can only use the DDS4 tapes A tape holds roughly 1200 images depending of course on your save mode Make sure you bring enough tapes with you If you prefer you are always free t
40. provided were written with primarily this sort of observations in mind 2 2 The infra red sky Beyond the optical window the atmosphere becomes increasingly opaque and ground based observations are only possible in certain atmospheric windows These are in the Johnson system called J H and K for wavelengths up to 2 5 um see Figure 1 The major atmos pheric absorbers and central wavelengths of absorption bands are H20 0 94 1 13 1 37 1 87 2 7 3 2 6 3 A gt 16 um CO 2 0 4 3 15 um N20 4 5 17 um CH4 3 3 7 7 um Os 9 6 um Cox 2000 The depth of the absorption troughs does depend on the water vapour con tent of the atmosphere Atmosphenc transmission Wavelength um Figure 1 Atmospheric transmission as a function of wavelength in the infrared wavelength range Cox 2000 At wavelengths longward of 2 3 um thermal emission from the atmosphere and telescope produces significant background see Figure 3 Shortward of 2 3 um the sky signal is domi nated by airglow emission from molecules primarily OH and O This background can vary significantly both spatially and temporally To obtain flat sky background levels over the wide field of OMEGA2000 a careful measurement of the sky level and shape is mandatory Sky variations constrain integration times and general observing strategy 02 12 2008 13 01 8 OMEGA2000 manual doc H20 Optical Depth T J H K L l M 1 2 3 4 5 6 Wavelength jum
41. taken This determines the behaviour of the level monitoring Functionality The filter and read out mode have to be selected manually before calling this routine The procedure takes test exposures with the minimum available integration time to calculate the time needed to reach the desired level Detailed behaviour depends on the time of the day Evening If the exposure level in the test exposure is above the specified saturation level no images are taken The procedure is aborted if the level is above the monitoring level as the sky is still too bright If it is between the saturation level and the monitoring level it loops back and takes another test exposure This is done until the level is below the saturation level Then images are taken with an exposure time scaled on the basis of the last test exposure to reach the desired level If the resulting exposure time turns out to be longer than 60sec the user is prompted for confirmation before the exposures are started Morning If the exposure level is above saturation the procedure is aborted If the resulting exposure time is longer than 60 sec the user is prompted for an exposure time when taking of images should be started Level monitoring is then continued until this limit is reached Then the images are taken Should the level reach the saturation limit in the shortest integration time available the procedure is terminated If check option is used a test exposure is taken after e
42. tele filter save none all macro 119 Waits for termination of the named process sync waits at least seconds before checking on any process to sync for to ensure startup of previous command which might need time on a busy system if none also with others is given it does not sync on processes If no process parameter is given sync waits for the termination of all background processes listed above and currently running in the system Without time specification might be given as float the sync waits at least 2 seconds 02 12 2008 13 01 If a parameter o the sync is star all string is like read This command is needed for writing macros do not block the execution of the next command A typical sequence could look like read sync tele rel save f sync tel read 2 e 10 10 i TE OMEGA2000 manual doc since commands this read wait move Save wait next f sync is given as just removed da ta for all running processes telescope 10 north da 10 east ta for the telecope stops read macro ted from inside of a macro or all and this macro or sync waits only as a command outside of a macro on the termination of t sync processes with t sync all sync none he main macro level macro without process specifications always waits on all he exception of the waits on al
43. where they are desperately needed 1 GEIRS GUI 2 DAT spooler 3 MIDAS session for quicklook 4 pipeline 5 observing We hope to solve the colour problem in the near future with the LINUX PC to be used as an X terminal with the dual screen 9 2 Start up Starting the GUI by pressing the OMEGA2000 button will show the start up screen l iinitialization window 4355 sy9b 7 Camera Omega2000 9 Camera Optic Camera Output 32 channels o Data dev pcdl amp dev pcdO RO Electronic jon tcp o2knport 409 Motors on tcp o2knport 409 Temp Controller offline o Telescope CA3 5m ui Focal Ratio 2 35 o Status on EPICS o Figure 34 Welcome screen of GEIRS to start the instrument Please enter your name as observer the rest should be set as in the figure After you give OKAY the GEIRS windows GEIRS Generic InfraRed Software appear and the desktop shown in Figure 35 will appear please note that in this example the telescope had been switched to OFFLINE Therefore the telescope GUI is not shown 31 02 12 2008 13 01 OMEGA2000 manual doc la T El 5 af 7 Jof cuts olo 3 ia ian save H0048 Save Options i focus series frame our comment ho a ta L4 lal ict Figure 35 Desktop to operate OMEGA2000 with the camera control the online display and the log window 02 12 2008 13 01 32 OMEGA2000 manual doc 9 3
44. within the cursor box Shows the mean and standard deviation of the pixels within the cursor box Shows the FWHM and total flux in counts of an object selected with the cur sor box Controls the display of a series of images Unless you need to review a set of images to determine for example whether the seeing was good enough to bother saving the data just leave this on last BAD Toggles between displaying the bad pixels in red or not Note that the bad pixels are ignored when determining display cuts only if the bad pixels are turned on The bad pixel mask is stored in path Cuts Display stretch control This button brings up a menu with various options for de termining the minimum and maximum display levels The options include 02 12 2008 13 01 e Cuts Allows you to enter your own minimum and maximum display levels in the Min Cut and Max Cut windows e 67 Sets the display range to cover 67 Yo of the full dynamic range of the data e 90 Sets the display range to cover 90 Yo of the full dynamic range of the data OMEGA2000 manual doc med3 Sets the display from mean 3sigma to mean 3sigma meds Sets the display from mean 5sigma to mean 5sigma 3 10 Sets the display from mean 3sigma to mean 10sigma minmax Sets the display range to cover the full dynamic range of the data Min Cut amp Max Cut These windows show the current minimum and Single Sum Ave Single will display each individual rea
45. 13 Glossary To be filled in later 147 02 12 2008 13 01 Appendix 14 Acronyms used CCD charge coupled device CDS correlated double sampling DSS digital sky survey see http archive eso org dss dss FOV field of view FPA focal plane array GEIRS Generic InfraRed Software 02 12 2008 13 01 OMEGA2000 manual doc 148 OMEGA2000 manual doc 15 References Bailer Jones C A L P Bizenberger and C Storz 2000 Achieving a wide field near infra red camera for the Calar Alto 3 5m telescope in Optical and IR Telescope Instru mentation and Detectors M Iye and A F M Moorwood International Society for Optical Engineering 4008 1305 Beckett M G 1995 High resolution infrared imaging Institute of Astronomy and Caven dish Laboratory Wolfson College Cambridge University of Cambridge 120 Cox A N Ed 2000 Allen s Astrophysical Quantities New York Springer Verlag FaDbender R 2003 Commissioning of the near IR camera OMEGA2000 and development of a pipeline reduction system Max Planck Institut f r Astronomie Heidelberg Ru precht Karls Universitat 95 Finger G 2002 Test report on HgCdTe infrared focal plane arrays Garchung European Southern Obervatory 18 Fowler A M and I Gatley 1991 Noise reduction strategy for hybrid IR focal plane arrays in Noise reduction strategy for hybrid IR focal plane arrays T S Jayadev 1541 127 133 Glass I S 1999 Handbook of infrar
46. 22h Astro 05h Astro 02h Astro 13h A Astro 13h B Astro 18h Figure 66 Elevation plots for the astrometry fields July and October 02 12 2008 13 01 142 OMEGA2000 manual doc Appendix 9 Photometric zero points Expected count rates for a star of Omag with flat spectrum in f filter photons cm s counts sec 2 37E 05 4 78E 09 1 10E 05 2 22E 09 Kp 8 25E 04 1 67E 09 9 32E 04 1 88E 09 Table 7 Photometric zero points counts for zero magnitude Measured limiting magnitudes provided by Sascha Quanz On source integration time 30min seeing 1 1 3o detections in all three filters give filter limiting magnitude 2MASS system J 22 0 H 20 0 Ks 18 5 During the HIROCS project 3ksec integrations in H were obtained The 56 limiting magni tude was determined to be 21 3 Vega with seeing of 0 9 143 02 12 2008 13 01 OMEGA2000 manual doc Appendix 10 Photometric standard stars The list of UKIRT faint standard stars as prepared by Dave Thompson is appended at the end of this manual We plan to update the fainting charts as soon as possible For the astrometry fields page 133 and focus fields page 125 we plan to give J H Ks magnitudes from 2MASS for some representative objects Otherwise the 2MASS web page provides more data under http www ipac caltech edu 2mass releases allsky index html 02 12 2008 13 01 144 OMEGA2000 manual doc Append
47. 32 A US a CS o 200 400 600 200 300 400 500 R tarcsec R tarcsec Figure 26 Centre to corner image distortion of the OMEGA2000 optics The ratio of the distance to a star at the centre for all objects from the measured position on the detector using the scale determined from the astrometric solution to the distance calcu lated from the RA and DEC positions Transmission of the optics was calculated from the transmission curves supplied by the manu facturer for each of the 4 lenses by multiplication O2Kk optics 96 1000 1250 1500 1750 2000 2250 2500 lambda nm 7 3 Filters For OMEGA2000 a set of 24 different filters is provided see Appendix 1 for a complete list and filter characteristics Inside the dewar we have three filter wheels with 7 openings each 25 02 12 2008 13 01 As we need one free opening per wheel and one wheel holds an aluminium blank for dark exposures we can keep 17 filters inside the dewar at one time Two additional positions are needed for two blocking filters as the detector is sensitive to beyond 2 61 the blocking limit specified for the filters Whereas the standard broadband filters J H K and K and the most commonly used narrow band filters like the H 2 1224 with the respective continuum filter will always be available the re maining positions will be equipped with filters requested for the up coming semester As we plan to open the dewar at most every half year it is mand
48. 5 1 The ob serving utilities use this coordinate system e UV is the rotated detector system Here any rotation of the mounting flange is also automatically taken into account This is not relevant for OMEGA2000 which is mounted at a permanently fixed angle of 0 on the front ring For the observations you should select the XY system The MIDAS procedures do this auto matically Coordinate zero point For object acquisition and tracking the telescope software makes use of a pointing model which takes into account any misalignment of the telescope s axes as well as flexure in the telescope structure The 0 order parameter of the pointing model is the zero point offset for both axes of the telescope This value should be set by Calar Alto staff who also select the appropriate pointing model Should the zero point not be correct you will not find your ob jects Here is the correct value QKORPAR T NULL 163 3 QKORPAR D NULL 0 To check the pointing accuracy use one of the stars in the astrometric fields provided in Appendix 8 The tables with the positional data from the M2000 and the UCAC2 catalogues are to be found on fire35 in directory disk a o2k MANUAL Focus position The nominal focus position for OMEGA2000 is 22700 T 10 C The temperature coeffi cient is 165 C Make sure the focus automatic which compensates thermal expansion due to temperature variations as well as flexure is activated during your observat
49. 5 frames The intermediate summation result is written to disk every 7 object frame c High quality reduction for normal observations o2k pipeline icat user specified frames 3 or 4 mode 2 3 sum 7 0 2 Uses the outlier clipping method for the sky determination with a to tal of 7 or 9 frames Only the final summation frames are written to disk d Improved quality reduction for observations of extended objects o2k pipeline icat user specified frames 3 mode 0 3 sum 7 0 2 Uses the minimum method with averaging of the 3 smallest values for the sky determination with a total of 7 frames Only the final summation frames are written to disk 83 02 12 2008 13 01 OMEGA2000 manual doc 14 2 Flowcharts for pipeline 14 2 1 Overview t 1 OMEGA pipeline prg parameter handling Main Modul open calibration frames IMAGE LOOP Single SJ lmage Reduction open output frames Flat amp Dark Correct Bad Pixel Correction Subframe Statistics Sky Modelling Sky Subtraction Summation Prep Alignment amp Summation 02 12 2008 13 01 84 OMEGA2000 manual doc 14 2 2 Sky Determination Image Stack T Subtract Sky E Add Constant and Unde Notinali ation ts Subtracted Ln age 85 Sky Modelli ng For Each Individual Pixel EM L1 EX zar L1 E E L1 LJ e E mmn 1 Median Qutliec Clippi moa P S
50. 8 4 93 1 4855 34 91 5 9 Chan 24 0 2102 4 76 4 3463 98 35 9 9 Quadrant 4 Chan 25 0 2234 4 48 1 9615 39 32 6 3 Chan 26 0 2352 4 25 2 7455 49 63 7 0 Chan 27 0 2256 4 43 6 8767 135 07 11 6 Chan 28 0 2101 4 76 1 2423 Chan 29 0 2089 4 79 4 3651 100 01 10 0 Chan 30 0 2122 4 71 2 5433 56 50 7 5 Chan 31 0 2132 4 69 3 1213 68 66 8 3 Chan 32 0 2274 4 40 1 6456 31 81 5 6 lt gain gt 4 87 lt RON gt 8 2 0 05 05 02 12 2008 13 01 94 OMEGA2000 manual doc Appendix 4 DAT spooler 23 drive O adl Fami spooler rmt O off online INT REWIND UNLOAD TAPE LIST files on tape 398 activity idle state tape loaded Figure 49 The GUI of the DATspooler Currently only one drive is supported This tool allows automatic saving of data during the night on a DDS4 DAT tape A further application of the tool enables to copy data to tape in offline mode A tape of length 150m will hold approximately 1000 images depending of course on the save mode Launching the spool system including the control GUI start datspooler first analyses the status of the tape drives If a tape is loaded which already contains da ta a warning is issued and has to be approved by the user Via the GUI the tape can be initialized deleting ist current content Data format on DAT The FITS files are written as blocked files with a blocking factor of 10 i e record length 28800 Files are separated by an EOF mark Using the spooler from within an ins
51. A2000 manual doc 13 2 Dome flats Function Call o2k domeflats ident lamp time coadd number save saturation Images are taken at the current telescope position The appropriate telescope position is t Oh and 6 30 Put the dome at azimuth 90 i e do not use the flatfield screen The files will have the names specified in the instrument GUI Filter and read out mode have to be set manually before call Defaults identifier no default lamp no default has to be 1 to 5 In case of 5 also the level is needed time no default coadds 1 images 1 save i ntegrated saturation 30000 Examples o2k domeflats dome H 5 1 3 Takes one image in a single exposure with lamp 5 at level Watt Exposure time is 3 sec o2k domeflats dome H 5 1 3 5 Same as above but 5 images are added up in memory and saved as an integrated image o2k domeflats help Help text Parameters external P1 ident Object name for the FITS header Use quotes if text contains blanks P2 P3 lamp The lamps are numbered 1 to 5 decreasing brightness Only lamp 5 can be adjusted in its level from 1 to 10 W Give level in addition to lamp number in this case like 5 1 P4 integration time The exposure of a single frame in seconds PS coadds 02 12 2008 13 01 52 OMEGA2000 manual doc Number of exposure repetitions in one read cycle P6 images Number of read cycles to be executed P7 save mode If integrated 1 is selected
52. Appendix 9 For a more accurate calibration photometric standard stars of known broad band magnitude are needed and we reproduce the standard lists from the litera ture and other observatories in Appendix 10 For narrow band imaging the calibration via these stars may be problematic depending on the accurate spectral run within the bandpass For these synthetic photometry may be more appropriate and we hope to supply the relevant data in the near future The 2MASS catalogue provides magnitudes in J H and Ks Due to the large field of view there will always be stars from this catalogue in the field for calibration The 2MASS cata logue may be accessed via the web page http www ipac caltech edu 2mass releases allsky index html 19 02 12 2008 13 01 OMEGA2000 manual doc 7 OMEGA2000 filling tubes outer nitrogen vessel dewar readout electronics warm mirror baffle inner nitrogen vessel detector unit filter unit cold plate cold baffle entrance window Figure 14 OMEGA2000 on the frontring cut away CAD draing 7 1 Detector The OMEGA2000 camera contains a focal plane array FPA 77 of type HAWAII 2 by Rockwell with 2048 x 2048 pixels each 18 u wide It is sensitive from about 850 to 2500 nm We provide in Figure 15 a measurement from ESO red together with the actually measured values in the three broad band filter J H K fo our detector blue A histogram of pixel values in a supposedly homoge
53. Dec 0 59 37 4 2007 758112 years 1 241180 airmass 13 01 98 OMEGA2000 manual doc HA 3 127500 deg H A 0 12 30 6 T FOCUS 24 995600 telescope focus mm CASSPOS 0 000000 cassegrain position rel to NSEW POLPOS 0 000000 polarizer position NODPOS A B main OBJECT HIROCS 03h 06b H 1 25 POINT NO 1 pointing counter DITH NO 1 dither step EXPO NO 1 exposure read counter FILENAME 26sep0104 fits PLNAME m31 mac macro template name IMERO 979 milliseconds IMER1 3012 milliseconds IMER2 2033100 microseconds PTIME 2 pixel time units READMODE line interlaced read read cycle type IDLEMODE wait idle to read transition SAVEMODE line interlaced read save cycle type CPAR 1 cycle type parameter ITIME 3 012000 on chip integration time secs HCOADDS Le if of hardware coadds PCOADDS d of of coadded plateaus periods SCOADDS 20 of software coadds NCOADDS 20 effective coadds total EXPTIME 60 240002 total integ time secs FRAMENUM 1 INTEGRAL OF 20 SKYFRAME 26sep0103 SAVEAREA 1 2048 1 2048 CHOPP F 0 000000 chopper frequency Hz CHOPP T 0 000000 chopper throw p p arcsec CHOPP M DE
54. E Pipeline Online Mode Once an observing macro has been started and has taken at least one image the pipeline can be started in online mode for the real time data reduction 81 02 12 2008 13 01 OMEGA2000 manual doc There are two ways to run the pipeline in online mode 1 Use the predefined command o2k online without any parameters This command uses the in catalogue information provided by the observing macro and the default calibration file It is using the fast median method with a total of 5 frames for the sky determination The intermediate summation results are written to disk every 7 image Note For this command the internal PRG parameters see above have to be set up properly 2 Usethe normal pipeline command with online specifications The pipeline is started in online mode by setting the image catalogue parameter to automatic o2k pipeline icat automatic other parameters This command also uses the in catalogue information provided by the observing macro but all other parameters can be specified by the user Working with online reduced data Each new output data frame is created by the pipeline in the following way 1 Create a plain image without any data 2 Write output data into the new frame 3 Close output image This implies that the output frames are visible in the reduced data directory after step 1 while the pipeline is still working with the opened frame The output data frame is only sa
55. FF E S j gc ES AT e 3 x m LJ F ox P Figure 52 Focus field at RA 9h M67 This field contains also 3 photometric standard stars red circles from top to bottom a J2000 amp J2000 K mag M67 IV 27 8 51 19 57 11 52 9 0 12 3 M67 IV 08 8 51 15 13 11 49 19 3 12 6 M67 I 48 8515 95 11 43 45 7 12 4 There are also more than 300 astrometric stars in this field from the M2000 catalogue 127 02 12 2008 13 01 Focus at 12h a J2000 12 25 25 15 OMEGA2000 manual doc 6 J2000 26 59 3 Figure 53 Focus field at RA 12h 02 12 2008 13 01 128 OMEGA2000 manual doc Focus at 17h 0 J2000 17 3 37 00 8 J2000 26 59 50 PS i zm I E A Es m E ae a I i P r1 i F y a E n E E Ll r3 E 1 F aT pF A a e de Ls s I E pl f 5 a i xn T a k P a prs L Li o ls n y e z a at z gt y A LS i F 1 a gt 1 u ry L i x c M a r E za Li F n xn i t 7 i E P ot t a T 4 z M E x 3 E E a Ji 1 2 E 5 Hes wm 7 ee ue a 1 Figure 54 Focus field at RA 17h 129 02 12 2008 13 01 Focus at 22h a OMEGA2000 manual doc a J2000 21 58 27 008 8 12000 20 17 50 1 k Ly 2j Li a i wa 7 ad Li a i
56. G158 100 SA92 342 Feige 1 SA93 317 Feige 16 Feige 22 SA94 242 SA94 251 SA94 702 GD50 5A96 83 GD71 SA97 249 Rubin 149 M67 I 48 M67 IV 8 M67 IV 27 5A100 280 162 66 6163 50 GD140 GD153 M3 193 SA106 1024 SA107 1006 SA108 475 M13 A14 SA109 71 G21 15 EG141 G93 48 SA114 750 GD246 Feige 108 Too bright for 00 31 22 7 00 52 36 0 01 01 46 6 01 52 03 7 01 52 04 7 02 27 39 2 02 54 47 2 02 55 12 9 02 55 38 8 03 46 17 4 04 50 25 4 05 49 34 8 05 54 33 8 07 21 41 2 08 48 21 9 08 48 31 0 08 48 35 4 08 51 02 1 10 31 14 5 11 05 27 6 11 34 27 6 12 54 35 1 13 39 25 7 14 37 33 3 15 35 59 9 16 34 26 3 16 38 54 2 17 41 32 5 18 24 44 5 20 39 41 9 21 49 53 0 22 39 11 3 23 09 50 4 23 13 38 2 Current ID not positive 3 Variable star 12 24 29 00 26 58 03 57 34 00 28 20 07 00 47 05 02 34 00 06 39 00 04 04 00 58 54 01 07 38 00 19 34 15 52 37 00 00 53 00 27 10 11 55 02 12 00 36 12 03 26 00 25 14 11 26 08 04 53 04 30 04 35 22 18 08 28 44 59 00 14 36 00 24 03 00 28 39 36 26 56 00 23 44 04 01 17 20 15 21 02 09 16 00 56 55 10 30 46 02 06 58 J K 0 46 DG K 0 25 0 22 sdB Sb os bo e 0 01 A0 0 14 DA3 oo do qa ONN z N 0 17 DA2 0 08 0 22 DAI 0 38 0 15 O9 B2p ttc o ooo Nok we Or b 0 23 DA2 0 12 DA4 bd No C gt Sn D N 0 15 Var aa Ca
57. H NM NH ERR 1024 clock pulses to read out a complete line 1 line 1 line 2 line 2 line 1024 line 1024 line Figure 17 The scheme of the reset level read reset read Non correlated Sampling or Single Correlated Read In the normal operation of the image sensor an integration time should elapse between the reset and the readout of the full frame so that some amount of photo signal could be collected The readout cycle of non correlated sampling implements this reset integration read scheme Figure 18 Now the resetting is separated from the readout process by integration which prevents the application of the fast reset method Since the exposure takes from the resetting of the first pixel actually the first line to the readout of it the resetting time of the full frame should be added to the integration time so as to obtain the total exposure time The integrated frame contains not only the signal collected during exposure but also the reset bias and noise as in the previous mode therefore this readout scheme is also suggested only for engineering function Reset Integration Read 1 line 1024 line 1 line 1024 line Figure 18 The scheme of non correlated sampling reset read Correlated Double Sampling or Double Correlated Read The scheme of Correlated Double Sampling CDS consists of a complete frame reset a read out of the full array an integration and a readout of the complete integrated frame The reset
58. ITIME_PLUS else the default value is 0 0 or 0 0 but may be always be changed via the itime command by the user itype type USER syntax itype type Set the integration type as IWR or ITR Without type it prints the actual integration type kill type USER syntax kill name 109 02 12 2008 13 01 OMEGA2000 manual doc Sends a software terminate flag to a subprocess if name is from display satcheck engwin sdisp gui control stripchart telgui tempcon shminfo rottab iniwin However a terminate does not necessarily mean that the process is able to catch the signal since the mechanism works passively sets a flag syntax kill name Send first a kill signal to a subprocess if name is from read save shell tele wheel filter lyot aperture optics If after timeout of currently 10 seconds the process has not been ended a kill 9 signal is send to the subprocess Additionally the PID entries and serial line flags are cleared and maybe some other flags which has to be reset lamp type USER syntax lamp on off in out offs offs Controls the calibration lamp slider and the power of the calibration lamp last type USER syntax last destfile Returns the last filename of the last image saved and stores it also into destfile which by default is in directory SCAMTMP mostly tmp the file geirsLstFile load type USER syntax load filename n Loads n FI
59. Kov cs 2006 The channel layout is show in Figure 16 Channels are numbered along the fast direction starting with quadrant I For more details on the detector see Appendix 3 4 B EN Ju Figure 16 Quadrant and channel layout for the HAWAII 2 detector left and H band twilight flat right The cut values for the flat are 130 black to 340 red 7 1 1 Read out modi implemented for OMEGA2000 This description of the read out modi is taken from the PhD thesis of Zolt n Kov cs 2006 There are three output modes available for the chip which can be controlled via the readout patterns In the Single Output Mode all data is routed through only one channel per quadrant If the chip is set to Eight Output Unshuffle Mode the data is spread across all the output chan nels of the detector namely eight per quadrant Each output provides data from 128 consecu tive columns The Eight Output Shuffled Mode is similar to the previous one except the data from each block of 128 columns is cyclically shifted to the next output bus In normal opera tion of OMEGA2000 the Eight Output Unshuffled mode is preferred because of its high speed The background limit will be reached in broad band imaging with HAWAII 2 array on OMEGA2000 in a few seconds Series of images are therefore required to achieve sufficient S R so it is very important that the array can be read out as with the minimum dead time The minimal integration time is
60. OMEGA2000 User s Manual Hermann Josef R ser With contributions from Peter Bizenberger GEIRS GUI Zoltan Kov cs detector Ren FaBbender observing macros pipeline Version 2 9 November 2008 Parts of this manual are based on the MAGIC and OMEGA prime user s guides The OMEGA2000 team P I project scientist Hermann Josef R ser Project manager optics Peter Bizenberger Mechanical design Ralph Rainer Rohloff Harald Baumeister Electronics Bernhard Grimm Matthias Alter Ulrich Mall Mechanics Armin B hm et al Cryogenics Werner Laun Software Karl Zimmermann Florian Briegel Clemens Storz Students Ren FaBbender Zolt n Kov cs OMEGA2000 manual doc Table of contents T THOU OO o de ea bere bn b Sete ma o eoe e ete tue Per des Noe Led 7 2 Astronomical observations in the infra red region sesssssssssseeeeeeeeeeene 8 2 T JAA OF tlie Balle aisi rte re tv vea ees re iecur dive led eddie hes leas 8 2 2 Theinfrasred SEV dise etos Wata AK aaa a ADS TAWA AWA MMO apud dotes escis Moe AA Dus 8 2 Detecting PNOTONS i cosa caste tensa assent Saal ene Lco eae tunt 11 3 1 Focal plane arrays for the infra red ii a a didas 11 3 2 Read out techniques in general ineo hid aia tpa reget ata aida 12 32 1 ESO C AA A AAA AAA 12 3 2 2 Reset read read double correlated read 12 3 2 3 Multiple end point sampling ecos DR oe NN 13 3244 Sample up he tamp deci dotes aedes Usa de port e Edda UT ON NEU HERI D
61. RE 13 4 Sources of noise signal to noise ratio and exposure times ssssssseeeeee 14 5 Ima ging e cu c e Lie rU 15 Del AVS AICS a field ETE N 15 25 2 Backeround SUD MACON ss s rois D Sere poet op ters obtusa AAA m SE TRE qu RR 15 6 Image calibratie oe ser rtc rt aue a aoe dde t e ba etd vasta OO bei Gk 17 6 1 Focussing the telescope onto the detector sse 17 6 24 Flat fielding orans o o tO ea too uta Roo Deb coat oe S acta 17 6 2 PES e ILI Pr 18 622 Dome MaS end shade Drop AAA vafe Ua I end cases A Uf 18 6 34 Dark current do o feed 18 6 Bad DELIS Eo ce eG ve E v ted A escas tea Se ee ee 18 6 5 Bu can det 18 6 0 Astrometric CaliDratioticzu s ue ete pH quive ds ca atu ev ba ei dr d aa 19 6 7 Phigtenietriecalbtatlofk oet osten e A das pd niu saletas e eA 19 LONE A a a a a a a 20 A AN 20 7 1 1 Read out modi implemented for OMEGA2000 sse 21 O O 25 QE KU DE WA AA INDORE RD NEUEN 25 TA DATES dos AA AA as a epa ou ts 26 TREO eleettOniQ8 eed ee A BI A rd a nde de Gia ER AAA 27 TO COEM a ese caedes e e Res EE ads atlas est e p eV 28 T OGL RE tou e DAE USC pH 28 8 The 3 5mctelescope asc e peri cab tenete a rl chu utet abies qiti ie e anie Rude 29 9 The graphical user interface GUD 22 dae ei oh res eek rer n dt Ne risa da Da eei dol 30 9 T A A ote eco a eee be A uie iara EE 30 92 Sa cU A e t Rn o m DeC t a t E 31 9 3 Ihe GU s Window mia ia 33 9 3 1 Camera control WIN Vins 33
62. SUPER syntax pipe nowait list command parl par2 Send command and parameters directly to the camera electonics No interpreation or limit checking is performed n owait just send command but do not wait for any answer l ist takes command as name for a command list file currently used in MIDI and OMEGA2000 pkginp type USER syntax pkginp h c devicename Starts read in process of GEIRS stream packages Accepts only devicenames starting with dev If no devicename is given the devicename has to be set via the environment PKGINPORT else you get an error should prevent accidential access of data ports just used Option h shows the command usage Option c first reads all waiting data until a timeout of a a part of a second polpos type USER syntax polpos value Writes value at keyword POLPOS into the FITS header ENG syntax ptime 4 not available with the MAX 10um camera and with Omega MPIA electronics put type ENG syntax put 1 f d s offset value 02 12 2008 13 01 114 OMEGA2000 manual doc Write value at offset into the shared memory infopage data base i value is an int default f value is a float d value is a double s value is a char pwd type USER syntax pwd Prints actual directory for the save operation UNIX style quit type USER synta
63. TS files into the shared memory Since the shared memory frame buffers are unsigned short integers the displayed values may be not correct You also have to switch the cycle type to reset read rr negative n add to shm logfile type USER syntax logfile filename If given sets filename as logfile name Otherwise prints the actual logfile name Format of the logfile UT FILENAME OBJECT RA DEC EQ AM ITIME COADDS WHEEL 1 WHEEL 2 T T UT universal time FILENAME first filename of this entry number of files in this entry OBJECT object name RA right ascension if DACS TECS connected else 0 0 DEC declination if DACS TECS connected else 0 0 EQ equinox AM airmass if DACS TECS connected else 1 0 ITIME on chip integration time COADDS number of coadded integrations per file HEEL position name of wheel 02 12 2008 13 01 110 OMEGA2000 manual doc ls type USER syntax ls switches filename Executes ls UNIX style ls type USER syntax ls Print contents of current save directory see dir lyot type USER syntax lyot name Move the lyot stop wheel to position name The named positions are defined in the file SHOME info wheel2 Without parameter this command prints all possible lyot p
64. The GUI s windows 9 3 1 Camera control window This is your interface to the OMEGA2000 camera Fields are changed by clicking into them However editing in the fields is not possible You always have to type your text anew In the top row three pull down menus provide further options Op Modules v option 7 optionsy Init Wheels Sound Re init ROElec SavePath System Setup SatCheck HacroPath StripChart ObjectPath Logfile Telescope INE ES MER EN Quit System Kill Shell 7 lamega2000 Controls 4355 BAFFLE SHIELD FILTER 1 FILTER FILTER 3 Wheel Macro L 1 Filename Options save Options rests Figure 36 The camera control window with its drop down menus 33 02 12 2008 13 01 OMEGA2000 manual doc The drop down menus provide the following options File Menu Init wheels sends all of the filter wheels back to their zero positions Re init ROE resets the read out electronics System setup will bring up the initialization window Help Close controls Quit system will quit the GUI Modules Menu The modules menu starts the different modules each of which has its own description section Display should start automatically Telescope Telescope control should start automatically Satcheck Turns on audible saturation warning Stripchart Keeps a visual record of the past sever
65. Then o2k dither is started and each dither offset will be corrected for any positional discrepan cies telescope drift if auto yes is given If the reference star is lost telescope glitch the user will be prompted to decide if observing is to be continued without autoguiding 65 02 12 2008 13 01 OMEGA2000 manual doc Autoguide is governed by a file containing the position of the reference star which is created by o2k offset once the offset had been applied automatically not by hand by o2k offset Make sure this file is up to date AY AX Figure 41 Standard dither pattern with 20 positions for integer pixel offset red and fractional pixel offsets blue repetition offsets Figure 42 Offsets for the repetition patter 02 12 2008 13 01 66 OMEGA2000 manual doc 25 20 15 10 Figure 43 Telescope positions for a complete cycle of 400 independent dither positions Basic pattern is shown in pink Comments 67 The observing macro prepares the online pipeline data reduction The name and path of the image catalogue and the integration time are stored in auxiliary files which can be ac cessed by the pipeline The image catalogue is updated with the name and path of the lat est image after every integration With each new telescope movement the time the offset and the dither number are written into a log file tel pos date log in the current directory The date
66. We will create a list of problems and if possible with solutions to help future observers avoiding the same trouble Problem You can t start the GUI Solution Type cleanup before you start the GUI This program deletes all remaining software parts from a previous session Problem Data is useless counts between 0 and 65000 randomly distributed and the Abort but ton does not work Solution The fibers are connected wrong Problem Anything seems to work well but there are no stars Solution 1 Check the last button in the display window Problem Message can t allocate info page and you can t start the GUI Solution There is still a shared memory socket existing Delete in the tmp directory the shmsocket 47 02 12 2008 13 01 OMEGA2000 manual doc 12 Observing strategies 12 1 Minimizing overhead There are several sources for overhead during OMEGA2000 observations which critically determine the observing efficiency e Telescope movement e Detector read out Telescope movements are especially important if extended objects are to be observed Here the overhead is determined mainly by the frequency with which sky fields are observed and how distant these are from the target In the case of sparse fields the dithering with short inte gration times and or low number of co adds also results in appreciable overhead The detector read out is currently limited to 1ir line interlaced mode in 32 channel mode For
67. XEL E p oo PIXEL o LST ORIGIN OBSERVER ESCOP FRATIO T O Zz Q Er ll E ll A ll Zz ll Z Z EAE Bi Dp E M q ll Ya 2 E ETE M Jj D OPTIC E PIXSCALE ELECGAIN ENOISE ELECTRON W1POS W2POS W3POS WAPOS W5POS B W6POS FILTER FILTERS STRT INT STOP INT RA DEC EQUINOX AIRMASS 02 12 2008 54370 12989426 Modified julian date days of observation 2007 09 27T03 07 02 8637 UT date of observation 2007 09 27T03 07 04 0134 UT date of file creation 11222 8637 03 07 02 8637 UTC sec at EOread 11944 900000 local siderial time 3 19 04 EOread Centro Astronomico Hispano Aleman CAHA Montoya CA 3 5m E2535 2 546250 degrees 37 222361 degrees 2168 000000 meters Omega2000 HgCdTe 2048x2048 IR Camera wide field 0 450000 arcsec pixel 4 150000 electrons DN 32 000000 electrons read MPIA IR ROelectronics Vers 2 NO OUT BLOCK HK OPEN none none q filter macro name of filter combinations BLOCK_HK H combination of all filters used 11159 8025 03 05 59 8025 start integration UT sec 11224 6949 03 07 04 6949 stop integration UT sec 46 630000 deg R A 3 06 31 2 0 993714 deg
68. Y cre type USER syntax crep n subrep subrepskip Sets the cycle repeat count This defines the number of images that will be read after a read command The options subrep subrepskip are available for Midi for faster setup Instead using options you may use for Midi the coadds command Both are complementary and only one of the possibility is needed for correct setup If options not given there values will not be changed 02 12 2008 13 01 104 OMEGA2000 manual doc ctime type USER syntax ctime time val Currently just returns the cycle time status ctype type USER syntax ctype name parameters Sets the cycle typ Number availabele depends on the actual camera Valid cycle types for Omega2000 are Uscr single correlated read like rr first full frame rst racer double correlated read like rrr first full frame rst wher double correlated read like rrr mpia fast line rst V rst line interlaced read a double correlated read like rrr fmpia mer multiple endpoint sampling read like mep also called Fowler sampling parameter number of reads per edg srr sample up the ramp read see also ramp parameter of reads on the ramp sub xxx subarray mode in corresponding xxx type parameters center x center y siz engineering modes of Omega2000 spr single pixel read stays on the pixel and clocks as
69. ach read cycle and the exposure time is adjusted accordingly This is the default 55 02 12 2008 13 01 OMEGA2000 manual doc 13 4 Focus test For the focus tests we strongly recommend to use the focus fields provided in Appendix 7 on page 125 These have been tested and work fine in most cases Problems were encountered for extremely good seeing and or some filters in the K band range narrow band K itself due to the high background We suggest that you use the H filter for focusing The focus will automatically be adjusted if you select another filter using the focus offsets measured under good seeing conditions Function call o2k focus root start index master focus step ima number itime total single action flag object number boxsize Remark o2k focus is an OMEGA2000 context command which calls the routine omega focus prg The focus routine can also be called without the context command in the following way O2K UTIL obs macros Focus omega focus Defaults root automatic take name from GUI start index 0001 only if not automatic focus no default prompt for estimated focus and step size 200 number 9 take 9 images itime 20 2 20 secs total integration 2 secs single integration action 0 1 take analyze and move focus show all graphics objects 40 search about 40 objects boxsize 18 total boxsize in arcsecs around objects for analysis Examples e o2k focus focus 23500 200 number
70. al doc 4 Sources of noise signal to noise ratio and exposure times When planning observations the basic task is to estimate the integration time necessary to achieve the required signal to noise ratio S N The following sources contribute to the noise Sky background S counts pixel sec Dark current D counts pixel sec Read out noise R electrons pixel read Object flux F counts sec The S N achieved for an object of flux F counts sec spread out over a circle of radius r on the detector pixel after an integration time of At seconds is then S FxAtx EPC N UF S D xxr x EPC x At rr xR Here EPC is the conversion factor electrons per count The integration time should as a minimum be so long that the denominator in the above for mula is no longer dominated by the read out noise Ignoring object flux and dark this requires R At gt Sx EPC Due to the variability of the night sky this integration time should also roughly determine an upper limit to the integration time Optimisation between adequately sampling the brightness variations in the sky background avoiding to be detector limited and keeping the number of data files at a manageable level is the primary objective in planning infrared observations The S N at short integration times i e in the detector limited range where the noise is domi nated by the read out noise is proportional to At In the background limited regime S N in creases on
71. al images Temp Pressure Displays a graph with the pressure and various temperatures inside the dewar Figure 37 Monitoring temperatures and pressure of the dewar Options Menu e Sound calls up a sound menu where a specific sound file can be associated with a va riety of different functions such as telescope moves completion of a read e Savepath Macropath and Objectpath tell the GUI where to save data and where to look for macro and object files e Logfile specifies where the log file is kept Note that the logfile path needs to be re entered each time the GUI is restarted and the other path parameters should be che cked Below the drop down menus various fields display the status of the camera and allow the setup to be changed Baffle shield To suppress background radiation at long wavelengths the baffle may be put into the de ployed position see Section 7 4 02 12 2008 13 01 34 OMEGA2000 manual doc Filter wheels While the control panel allows for addressing each wheel separately all requests for filters should be made from the wheel macro panel where all standard observing configurations are available The individual filter wheels should say moving as the wheels are being reposi tioned then display the actual position filter name open or blank when set Read setup Mode The different read modes available are described in detail in Section 3 2 For standard broad band observing this should
72. alar Alto the standards FS08 FS09 FS26 and possibly FS25 de pending on the seeing are too bright to be used as standards they saturate in the minimum exposure time for this camera DISCLAIMER Every such document must have the obligatory disclaimer preferably in unreadably small print so here is mine Every attempt has been made to provide accurate finding charts positions and magnitudes for these standard stars As in life however there are no guarantees so use this information at your own risk FS 16 FS 18 FS 23 FS 24 e Q YN E FS 28 FS 33
73. all exposures taken in a single read cycle coadds are summed up in memory and stored as a single file on disk In single s mode the ex posures are stored individually P8 saturation The saturation level above which the procedure will be aborted 13 2 1 Operating the flatfield lamps The lamps are permanently mounted on the southern telescope base They are either operated via the GUI 1 or via shell commands To launch the GUI type ffl amp in any xterminal on the fire35 The GUI will pop up If you want to operate the lamps from shell commands as is the case with the above com mand 02k domeflats in MIDAS the GUI has to be shut down via the QUIT button first Shell commands 53 f f lats flats lats flats ALLOFF Li on L5 on lev Li off turn all lamps off turn on lamp i i 1 4 turn on lamp 5 with level lev lev 0 9 turn off lamp i 02 12 2008 13 01 OMEGA2000 manual doc 13 3 Taking twilight flats Function call o2k skyflats ident level coadds number offsets check saturation time Remark o2k skyflats is an OMEGA2000 context command which calls the routine skyflats prg The routine can also be called without the context command in the fol lowing way O2K UTIL obs macros skyflats Defaults ident no default level 20000 maximum level in a single exposure to be 20000cts coadds 2 exposures are added up in memory to a single image
74. an only be extracted from the science frames taken shortly before and after a given image From these the contemporary sky frame is extracted by a me dian like procedure and this is then subtracted from this particular science frame see Section 14 for details This procedure has to be taken into account planning observations For extended sources dithering this way is not appropriate as no pixel will see pure sky in most of the images Therefore additional observing time has to be included to measure the sky level by offsetting the telescope by amounts large enough to bring the target out of the FOV Variations in the shape of the night sky emission cannot be removed this way however In order not to loose too much telescope time with sky observations whose S N per pixel should be larger than the object frame in order to preserve the S N of the science frame during sky subtraction one should smooth the extracted sky frame see Sections 6 17 and 6 18 for de tails n the MAGIC manual this is called the moving sky technique 02 12 2008 13 01 16 OMEGA2000 manual doc Image calibration 6 1 Focussing the telescope onto the detector The optimum telescope focus changes mainly with temperature of the telescope structure For the 3 5m telescope this change is 165 u C A smaller effect is introduced by flexure of the telescope mount Once an initial optimum focus is found the automatic focus compensation by the telescope computer ta
75. and can be invoked with the ctype instruction from the command line interface and from macro files Their detailed properties beyond the general principles described here will be presented in Section 7 1 1 3 2 1 Reset read read Figure 7 Read out mode reset read This is the simplest readout scheme The pixels are reset and read out once at the end of the integration This does not remove the variable pedestal level KTC noise and any initial off sets which can vary from pixel to pixel We do not recommend using this mode for observa tion Its main usefulness is in checking the signal level for saturation 3 2 2 Reset read read double correlated read reads Figure 8 Read out mode Double correlated read Also known as Double Correlated Sampling this is the most commonly used mode for gen eral observing The array is read immediately after the initial reset and before the final reset at the end of the integration This eliminates the kTC noise and other offsets but increases the read noise by 2 because the noise from two readouts goes into a single image We recom The variability is caused by a quantum noise source called kTC noise the thermally induced fluctuations of voltage on a capacitance C at temperature T 02 12 2008 13 01 12 OMEGA2000 manual doc mend this readout mode particularly for broadband imaging where you reach the background limit quickly and can thus accept the higher read
76. ands are finished tele rel 25 25 move the telescop save i f 2 save the data as integrated starting from the second frame sync tele wait until only telescope move is finished save will con tinue read start the 2nd read sync wait until all previous commands are finished tele rel 50 0 save i f 2 sync tele read sync tele rel 0 50 save i f 2 sync tele read sync tele rel 50 0 save i f 2 sync tele read sync tele rel 25 25 save i f 2 sync tele All macro files must have the extension mac and are started from the camera control win dow lower part see Figure 36 Macro Commands In a complete list of macro commands is given These commands and syntax can be used in macros or typed directly into the command window Use with caution some commands are better left out of macros For example quit will exit a macro at the point it occurs no further instructions in the macro will be executed Also if interactive is on and ls dir or history are used in a macro the macro could stop executing and wait for a carriage return Double buffering 45 02 12 2008 13 01 OMEGA2000 manual doc It takes a considerable amount of time to transfer the data from the camera and save it to the hard drive on the workstation To reclaim some of this otherwise lost time Omega prime has been configured with two image buffers Thus a new image can be read out while the previ ous image is being saved
77. at the beginning by source datspooler cshrc How ever in most instancies this is done by the instrument control software Files used by the spooler DATSPOOLER_DIR common spool dat spool DATSPOOLER_DIR common spool dat tmp Holds the name of the files to be saved following the call QueueFiles path file After that thsi file is copied to dat tmp Programs All programs are located in DATSPOOLER DIR bin Those starting with DAT are called from other routines but may also be used directly DATeod dev Writes an EOD end of data mark to tape If done at the begin ning of the tape this deletes the tape reset tape DATeof dev Writes an EOF end of file to tape DATeom dev Positions the tape after the last file end of medium DATfsf dev nfiles Skip forward by nfiles files marks DATrew dev Rewind the tape 02 12 2008 13 01 96 OMEGA2000 manual doc 97 DATtst dev Read tape status DATunl dev Eject the tape FitsList dev nfiles firstfile QueueFiles path file fits oder newdata sav QueueControl StartTapeSpooler datSpooler csh datSpooler 0 datSpooler 1 datSpoolerKillDisplay csh 02 12 2008 13 01 Appe SIMPLE BITPIX NAXIS NAXISI NAXIS2 COMMENT BSCALE BZERO UNIT TYPEl1 RPIX1 RVAL1 ae ee ae EIAS E H ll OMEGA2000 manual doc dix 5 FITS keywords written by OMEGA2000 32 2 2048 2048 op oo DU PIXI PI
78. atory that you clearly specify your filter needs in the application for observing time It will not be possible to use special filters on short notice 7 4 Baffles Due to their sensitivity to the surrounding thermal emission from dome and telescope infrared cameras need an elaborate baffling system For systems with an intermediate focus like OMEGA Cass a cold Lyot stop is the most efficient way to block back ground light This is however not possible in the optical design of OMEGA2000 We thus have to rely on a set of warm and cold baffles that are meant to reduce the background signal e A cold baffle at the dewar entrance window is placed as far from the detector as feasible to narrow down the solid angle of warm background seen by the detector In order not to vignette the signal from the sky this baffle still al lows the detector to see parts of the warm dome floor e A fixed warm baffle with the shape of an ellipsoid whose foci are at the rim of the cold baf fle reflects rays from inside the dewar back inside Rays from the ouside hitting the baffle are not re flected into the dewar This baffle does not vignette the beam e A movable warm baffle of the same principle properties as the fixed warm baffle may be deployed for K band imaging It does vi gnette the beam constant across the field but the loss in object sig nal is more than compensated by the reduction in thermal back ground With this baffle deplo
79. ax satc Swit intg heck on limit ches the saturation check on 1 lute counts of the A D converter about 10000 55000 The non linearity starts at t 40000 counts which is the default limit sound is on you get a accoustic warning The optional limit uses These counts range heck off ches the saturation check off This is recomended at ration times smaller than about 150 ms Magic Cameras Save type syntax Save cycl ATTEN comm data Es di z Siss t b g d save all 1 r nl n2 p Pee Pat qd filename devname c z n or g F frames in the shared memory according to the actual e type ctype ION All files starting with the prohibits the automatic storage on tape with the datspooler tool at CalarAlto a delimits multiple saving sets done from the same might be sequential or parallel executed from software save from frame n first frame is save upto frame n last frame is save only frames from nl through n2 save the integral of the selected frames write all images into one FITS file FITS cub images as FITS bin table file Jaf he data into fitstable batches and Split the data into single DCR images and do not create FITS S Just dump the s framebuffer Default is all Jae fe Cotton write to dest te to dest hared memory split t wri Fil C
80. c p Save not overwrit xisting files for the actual sequence bu this save operation only the previous one S Sp saving au af C If 02 12 2008 13 immediate direct buffer in contrast to normal which is saving the data d up version of autosave by while reading the buffer the s option filled tosave withou ter buffer is urrently only supported for MIDI batches and tables used in a single save command it takes the current read buffer for parallel saving 01 116 OMEGA2000 manual doc At tention Option p is only thought for interactive usage It is not a good idea to use it in a macro If no filename is given the default filename is used With option b the filename might be a device dev pcdl Example sav peuple el Lu which saves the previous sequence as cube fits previous sequence as integrated single fits image actual sequence as cube fits and actual sequence as integrated images After a save the filesystem will be frequently checked If the capacity is below a certain value you will get a warning from the system Examples save b s immediately batch stream to PKGOUTPORT intf sav b s filename immediatelay writes the batch stream to a file sav t filename wirtes as a single FITS table fil save g s immediately DCR img stream to PKGOUTPORT intf sav g s filename immediat
81. case the exposure time is set to time P7 save mode The images of a read cycle are saved either as single files s or integrated 1 in mem ory and saved as one file P8 reset Before exposure time is changed a reset is performed in that sense that the exposure time is set to the minimum time then two images are read out without saving them Then the exposure time is set to the desired value This should help eliminate the fifo overflow problem now hopefully solved no reset suppresses this feature Functionality The desired filter and the read out mode have to be selected manually before this routine is called The exposure times for the number of specified images is calculated as follows The interval between minimum and maximum time is divided linearly or logarithmically into n segments If the exposure time is less than the minimum time allowed by the read out mode it is set to this minimum time Therefore if the exposure times are such that also fur ther images are still below the minimum integration time several images will result with minimum exposure time If no increase in exposure time is selected zero the exposure time is set to the maximum time specified in parameter 3 Note about darks We found out in September 2004 that the filter wheel is not absolutely light tight So in taking darks you should put the J low filter into wheel 1 blank in wheel 2 and e g H in wheel 3 51 02 12 2008 13 01 OMEG
82. ced in real time LABEL icatalog Sky frames Number of frames on either side of a master frame for the sky determination Thus the total number of frames used for the sky is 2 sky frames 1 LABEL frames 02 12 2008 13 01 OMEGA2000 manual doc P3 sky mode mode specifier Mode for the sky determination 3 different sky modes are available minimum mode fast median mode and the outlier clipping mode The modes can be specified via an integer flag or via a string identifier The minimum and outlier mode have a second specifier 1 Minimum mode mode 0 n or mode min n n is an integer specifying how many of the smallest values are averaged n 1 is the real minimum n 2 takes the average of the 2 smallest values and so on 2 Median mode mode 1 or mode med Takes the median of each pixel col umn 3 Outlier clipping mode mode 2 k or mode out k k areal number speci fiying the clipping threshold as k sigma above the median All outliers are clipped off before the median of the remaining values is taken LABEL mode P4 sum parameters n average action flag sum save flag Parameters for the summation of single images n average integer specifying from how many images the reference sum frame is calculated If the sum save flag is set to 0 an updated summation image is written to disk every n average images action flag Specifies the data reduction action 0 do reduction and summation of all ima
83. ched with a graphic and a display screen So this is the one to be used for any interactive work On the other hand it should not be blocked by launching a long observing session from here The following utilities need this window e focus test Section 13 1 page 50 e offsetting the telescope to pixel accuracy Section 13 8 page 72 e seeing measurement Section 13 7 page 72 This is MIDAS session 31 9 4 2 Observing The white X terminal is ment to host observing commands that take a long time to execute e g the ok2 dither Section 13 6 1 page 63 This way one can take a closer look at previous images or results from the pipieline in the quick look terminal This is MIDAS session 32 9 4 3 Pipeline The yellow X terminal is reserved for executing the online data reduction with the OMEGA2k pipeline Section 14 page 76 This is MIDAS session 33 As observing commands may require the availability of the display etc it is essential to use the appropriate MIDAS sessions For some more critical commands we check in which win dow the command is launched and abort if this is not the appropriate one Any further MIDAS sessions launched with inmidas p fii where ii is the session number must not use the session numbers 31 to 33 A few basic MIDAS operations e g to display an image are given in Appendix 12 n general all UNIX commands can be issued from within MIDAS if they are preceeded by sign 02 12 2008 13 01
84. culi i eet 1 5 Tii L n i A F mi PA ELE la pi E rs ra p MIT LEM E Lm RA er cel k E t a DARIE i a Se eit in e x a ani E a Es te os 5 47 7 ipu E E Is E v P idm ig 44 m a T x s i Y A ia i QT La a a EE x LE E LL ika Ta e zi 4 E q 5 pis mer E za s MW nC HEN ID is i E P RE 1 2 4 I ET a rs a k am 3 Wi 1 Li a NT po r La y Tef k tgi e no 1 A mde 1 3 244 0 a 2 oe mul uoc DERE opi apr 1 E E i i ij gat J s T y n rt Di ub E grim je 2 ES i p xo esi mon gt AATE Et xL EE BES Eri UM GIAN 1 E d t F z T ol wa Bos y i EUN A a ia SAC 4 i j 1 OE E y e DA ray 2 MR a me E D i Ti E aa Lis E E pa a E d a a Pate ss Tee A p sn Tk oa 1 FW S nt OA et DES ya at gt i F a E En 2 n i ki j i L 1 x i Ms 1 E E EU ta DR r i JE x 1 TE a LI a d c T i a i bpo ii PET A i MEN Ge eae et AATE M Figure 63 Astrometry field at RA 18h finding chart for astrometric stars from M2000 139 02 12 2008 13 01 OMEGA2000 manual doc Astrometry 22h 13 43 13 38 13 33 c o LL a 13 28 13 23 13 18 22 345 22 340 22 335 22 330 RA h T Sa T EL t Te a EP ae hek k Ld 1 r z 4 s i Pi E T b a i E 1 hA 1 3 a d a m gt t ide ai um Fa T A ri E Fe T 7 i Too re T E Sth E AS
85. currently restricted to the looping counter inside of ROE2 by maximal value 8191 available for Max128 Max256 as HW coadding w o skipping option continue type USER syntax continue Continues paused macro and commands controls type USER syntax control x xserver f font opens the main camera control GUI window x where to open the window e g xt28 0 f font family e g lucida counter type USER syntax counter name action set value incr count changes the counter name according to action clear or clr sets the counter name to 0 incr increments counter default 1 decr decrements counter default 1 set Sets counter to set value examples counter EXPO NO is automatically incremented after each read execution counter lists the current counters and its values counter EXPO NO shows the counter EXPO NO value counter EXPO NO clear sets the counter EXPO NO to 0 counter EXPO NO incr increments counter EXPO NO counter EXPO NO decr 2 decrements counter EXPO NO by 2 counter EXPO NO set 99 sets the counter EXPO NO to value 99 next read will increment that value saving of current image without read takes the old value to prevent interfering with current ongoing save cplats type USER syntax cplats Set number of co added plateaus in cycle types chop and chop d Max ONL
86. d as it comes Tele Movie Image Sky Send played except if using the Cuts op tion off the camera Sum will display the sum of all im ages taken in the current series Average displays the average of all images taken in the current series Provides for offsetting the telescope directly from the image dis play which is useful for centring standard stars or science objects Click on the tele button to get a green circle Place this circle on some object on the display and click there Calculating centroid Move the cross which appears to where you want this object to be moved Plays a movie of the series of exposures currently in memory shows which image in a series of repeated exposures that is currently being displayed The sky button small square tells the computer to subtract a sky frame from the images before displaying and is on when the square appears green The file used for the sky frame is specified by name in the window to the left of the button This sky subtraction also effects the pixel values displayed in the upper part of the window Be aware of this when checking count levels saturation of a displayed image Send the current image to the data base of the strip chart Sum Ave maximum levels used for the display They will BAD u automatically update each time a new image is dis 9 3 3 Telescope control window Telescope Controls 4355 sv9b x04 CA3 5m f 2 35 0 45 pix AH 1 075 UT 02 37 54 ST
87. d at the beginning of the rou tine Pixel saturation Maximum count level per single image exposure in the linear detector regime Minimum and maximum galaxy cutoff parameters The empirical FWHM cutoff parame ters for the final object selection step Trouble shooting The standard focus test involves an automatic object search on the central master image supposed to be approximately in focus In case of exceptionally good seeing or high back ground K band this search may fail and you will not get a valid focus measure To help the software find objects under good seeing conditions it is possible to shift the master frame by specifying the second part of parameter P2 giving the index number of the alternative master Example root F index 271 i e images F0271 F0279 are the focus test Default mas ter is F0275 By giving P2 271 273 you select image F0273 as the master All the rest remains as before o2k focus F 271 273 23800 200 9 20 2 1 1 will re analyse the focus series F0271 279 already taken with the master being F0273 In case you experience problems no objects found and do not want to rely on the focus off sets you may have to evaluate the focus test manually Proceed as follows Flatfield the focus exposures Select one object not saturated if possible in the optimum focus image Use center gauss to measure its half width for each focus test Plot the FWHM as a function of focus position Fit a parab
88. detector technology Both have direct consequences for the observing procedures and will be described in detail in this manual Once a raw image and its associated calibration files are obtained the data reduction and analysis for both wavelength regimes turn out to be identical This manual comes in three parts In the first part we describe IR observations and technology in general Sections 1 6 The second part describes the instrument and the control software Sections 7 11 Finally we give detailed instructions on how to use the OMEGA2000 cam era at the telescope in Section 12 The latter contains also a description of the pipeline soft ware available at the telescope allowing the user to get preliminary reduced and stacked data at the telescope A good introduction to infrared observing and technology is given by Glass 1999 Rieke 2003 2007 provides a detailed description of detector technology in the infrared 7 02 12 2008 13 01 OMEGA2000 manual doc 2 Astronomical observations in the infra red region 2 1 Aim of the game OMEGA2000 is using one of the first HAWAII 2 detectors giving an unprecedented field of view for IR cameras of 15 4 on the sky As such its prime application will be survey work Due to the nature of astronomical objects this will be targeted towards the dusty the cold and the distant universe One should keep the survey application in mind when using OMEGA2000 because e g the observing utilities
89. e dis play will not fit onto your monitor screen in this case e Slave Opens a second display window at a size of 1024x1024 pixel on a second screen e Quit Quits the display module It can be restarted by selecting dis play under the module menu of the camera control window Color Menu selects the colour look up table for displaying images e gray is a black and white colour look up table e temp is the standard temperature colour table e bb is the standard blackbody colour table MagMode Menu switches between the zoom window and a measurement of the e Magnifier Zoom window this is the default mode e FWHM log Measures the FWHM of the indicated object each time a new image is displayed and plots a running history of v MagMode the values This is useful for rough focusing Note that to get ca reasonably accurate measurements of the FWHM the aperture of the box used set with radius see below must be large a enough to include a couple of rows of sky pixels around the ob 418 I 2419 OMEGA2000 manual doc image seeing Magnifier FHHH Log ject you are measuring Pixel Radius min max mean dev FWHM flx First Last When the cursor is in the image display window the pixel position and counts in that pixel are displayed here Sets the radius of the small cursor box in the image display See the above note on FWHM log about measuring the seeing Show the minimum and maximum values of the pixels
90. e file SO2K_UTIL obs_macros Tilt make_bdf prg e The internal parameters for pixel saturation and the stellar cutoff can be adjusted to opti mize the output quality Function Call The function call o2k tilt will prompt the relevant parameters estimated focus value number of images step size name of first image in the above format name of master image image with the estimated focus in the above name format number of objects and box size Note The use of the default value for box size is suggested it is specified in pixels The de fault for the number of objects is 200 which is the maximum the search routine can handle Example o2k tilt typical inputs at the prompt would be 24000 estimated focus 7 or9 gt number of images 200 gt step size focus001 gt name of first image with full name focus001 bdf focus004 gt name of masterframe if 7 images were used default gt object number default gt box size e The results are stored in the output frame tilt frame bdf which contains the local fo cus deviation compared to the average focus over the field of view The average is set to the arbitrary value 100 000 the deviations are given in microns Appropriate cuts are thus 99900 100100 61 02 12 2008 13 01 OMEGA2000 manual doc e Iffocus series at different telescope positions exist i e the stars are at different detec tor locations the results can be combined into one output frame with a lar
91. e last column Filter Her 208 selection should always be done via Pes 25090 the wheel macro which automati wh o 2 122 Oo cally inserts the appropriate block continuum 2 144 ing filter and corrects also the focus Po Shift Br y 2 166 H 2 24 Using a blocking filter changes the Z image scale by 2 5 1000 continuum 2 260 Table 4 Narrow band filters All wavelength specifications are in micron 89 CO 2 205 supergiants 02 12 2008 13 01 OMEGA2000 manual doc z zJ Jlow Jhigh transmission Methan off 1 000 1 200 1400 1 600 d 2 000 2 200 2 400 Methan on wavelength nm Figure 47 Transmission curves for brad band filters Hel Pay continuum 1 01 Fe II Pap Fell continuum 2 Hel transmission Hs continuum 3 Bry 1 000 1 200 1 400 1 600 1 800 2 000 2 200 2 400 a H3 continuum 4 co LIILlnl JJ wavelength nm Figure 48 Transmission curves for narrow band filters 02 12 2008 13 01 90 OMEGA2000 manual doc Appendix 2 Flat field exposure times Dome flats The exposure times are for a count level of 15 000 cts pixel Filter Acentre u lamp Mirror cover At sec remark T O 1 1 1 1 wama EN RR RN UN Jsmall 1 187 E continuum 1 207 E n or um 1 T Fen 1s 1 TL Pa p 1282 Fe II 164 continu
92. e pointing is accurate to about 10 If you require higher accuracy you need to calculate the expected position of a reference star in your field e g from one of the following catalogues and the desired pointing center e USNO http www nofs navy mil data fchpix e M2000 http www obs u bordeaux l fr public astro CSO equipe JF M2000 m2000 htm e UCAC2 http ad usno navy mil ucac Due to the excellent image quality no image distorsion needs to be taken into account 02 12 2008 13 01 72 OMEGA2000 manual doc 13 9 Relative calibration of survey fields o2k relcal identifier dit ndit Relative calibration of an OMEGA2000 mosaic of 1 square degree blue squares in illustra tion below by taking 3x3 pointings red squares on intersection of the mosaic exposures Telescope is assumed to be positioned in centre of 4x4 mosaic O at start Filter and read out mode have to be set before calling this routine 13 10 Determining bad pixel mask and dark frame The mask for bad pixels and the dark frames dark signal pixel sec are needed for the pipe line reduction Both are conveniently obtained from a series of frames with increasing expo sure time the bad pixel mask from flat fields the dark images with the blank inserted Fitting the signal for every pixel as a function of exposure time with a straight line isolates well be haved pixels in the flatfield series those following a straight line from the bad ones by ana
93. ed astronomy Cambridge Cambridge University Press Kitzing A 2006 Calibration and otimisation of the infrared camera OMEGA2000 Max Planck Institut f r Astronomie Heidelberg Ruprecht Karls Universitat 70 Kov cs Z 2006 Test of the Infrared Wide field Camera OMEGA2000 and its Application for an Extragalactic Survey Max Planck Institut f r Astronomie Heidelberg Ru precht Karls Universitat 167 Leinert C et al 1998 The 1997 reference of diffuse night sky brightness Astronomy and Astrophysics Supplement Series 127 1 99 Maihara T et al 1993 Observations of the OH airglow emission Publications of the Astronomical Society of the Pacific 105 940 944 Ramsay S K C M Mountain and T R Geballe 1992 Non thermal emission in the at mosphere above Mauna Kea Monthly Notices of the Royal Astronomical Society 259 751 760 Rapaport M et al 2001 M2000 An astrometric catalog in the Bordeaux Carte du Ciel zone 11 lt lt 18 Astronomy and Astrophysics 376 325 332 Rieke G H 2003 Detection of light from the ultraviolet to the submillimeter Cambridge U K Cambridge University Press Rieke G H 2007 Infrared Detector Arrays for Astronomy Annual Review of Astronomy and Astrophysics Palo Alto CA Annual Reviews Inc 45 77 115 Rousselot P et al 2000 Night sky spectral atlas of OH emission lines in the near infrared Astronomy and Astrophysics 354 1134 1150
94. eed with yes Documentation of all MIDAS commands is given in the help GUI in the quicklook desktop Furthermore the ESO web pages provide an introduction to MIDAS Please refer to http www eso org projects esomidas doc user 98NO V vola index html Sounds Some utilities run for a relatively long time In order to alarm the observer if an action has to be taken or if something went wrong sounds are played Please make sure that the speakers are connected properly to o2k1inux The following events are signalled by sounds e End ofa procedure gong e User is prompted doorbell e Result is displayed no immediate action necessary whistle e Abort or error crash e Input error sorrydave If you want to test the sounds please use the shell command auplay disk a staff GEIRS SOUNDS sound name au where sound name is to be substituted by the above given names Please note that the sounds described above are independent of the sounds issued by GEIRS see upper right in Figure 36 for the window where to control GEIRS sounds Most of these utilities have been prepared by Ren Fafbender in the context of his diploma thesis 49 02 12 2008 13 01 OMEGA2000 manual doc 13 1 Calibration series Function call o2k calser ident time coadds number spacing save reset Remark o2k calser is an OMEGA2000 context command which calls the routine calibration series prg The routine can also be called without the conte
95. ely DCR img stream to a file Current PKGOUTPORT interfaces middi dif dev PCDxx save is a background process and should have a sync after it when used in a macro set type USER syntax set macropath pathname Print or set path for macros syntax set objectpath pathname Print or set path for object files shminfo type ENG syntax shminfo x xserver n t sec Opens a window to display shared memory info page entries x where to open the window e g xt28 0 n of entries default 6 t 4 4 seconds of pausing Sky type USER syntax sky filename Writes filename at keyword SKYFRAME into the FITS header slee type ENG syntax sleep Suspend execution of shell macro for seconds This is the same as with sync none 117 02 12 2008 13 01 OMEGA2000 manual doc sndwin type USER syntax sndwin Opens the sound selector window You may also set the volume and the output channel sound type USER syntax sound on off o speaker headphone v 0 100 Enables disables sound after some operations like read filter aperture lyot telescope macro or as a warning if the saturation check is on Default is off o output headphone speaker v volume 1 100 Without parameters sound prints the sound status status type USER syntax status Returns the comlete status list depending from
96. ely populated field sss 87 Figure 46 Pipeline result for an image of an extended object sss 88 Figure 47 Transmission curves for brad band filters see 90 Figure 48 Transmission curves for narrow band filters ooonoconicnnncniccnncnocncocanoncnancnncnancnnncnnos 90 Figure 49 The GUI of the DATspooler Currently only one drive is supported 95 Figure D0 Focus feldat BA TBsu oe odore Sure cated cre a a a a a 125 Figure 51 Focus field at RA 5h NGC 1647 sese eere nennen entren 126 Figure 52 Focus field at RA TAM iia 127 Figure 53 Focus field at RA I2 ee one nere da 128 Figure 54 Focus peld at RAT Te s o oe y tap matti eie Kaa d pee 129 Figure 55 Focus eldat RA 722 s een utet abe p tab aaa 130 Figure 56 Elevation plots for focus fields January and April esses 131 Figure 57 Elevation plots for focus fields July and October sss 132 Figure 58 Astrometry field at RA 2h finding chart for astrometric stars from M2000 134 Figure 59 Astrometry field at RA 5h finding chart for astrometric stars from M2000 135 Figure 60 Astrometry field at RA 9h finding chart for astrometric stars from M2000 136 Figure 61 Astrometry field at RA 13h finding chart for astrometric stars from M2000 137 Figure 62 Astrometry field at RA 13h finding chart for astrometric s
97. eratures during cool down sss 28 Figure 32 Control panels on the display after login as user o2k sse 30 Figure 33 The available screens to operate OMEGA2000 cooococcccoccoccoonconcconononcnnncnnanancnnccnnoo 30 Figure 34 Welcome screen of GEIRS to start the instrument sse 31 Figure 35 Desktop to operate OMEGA 2000 with the camera control the online display and the Tos Sando Wa oit etta Ely eta nq d des ey nod SU epe Da ta bi s AU AC wands 32 Figure 36 The camera control window with its drop down menus ess 23 Figure 37 Monitoring temperatures and pressure of the dewar sss 34 Pipure o A d ia DO a en red EE 35 5 02 12 2008 13 01 OMEGA2000 manual doc Figure 39 Realtime display euet baee coasts A A ti ora e ihe ah NO tn 37 Figure 40 Telescope control window iq ueber eese ener dias 39 Figure 41 Standard dither pattern with 20 positions for integer pixel offset red and fractional pixel offsets blue itn eor aeu i ide tee qnl be eR iv Qr eras 66 Figure 42 Offsets for the repetition patter iiu eoi ee ro coti rt ea em as ende di tactics 66 Figure 43 Telescope positions for a complete cycle of 400 independent dither positions Basic pattern is shown in DIU eee ee eei Mene ER OD PE P PB E eens NER CANNE RENTES 67 Figure 44 Sky positions for observations of extended objects sss 71 Figure 45 Pipeline result for a spars
98. ers J H K and Kp are supported 13 12 List FITS files on disk To list FITS files on disk proceed as follows o Inany MIDAS session change to the path where the files are located e ch dir disk b o2k DATA o Create an image catalogue of the FITS files create icat raw fits o cat O2k list file frame list eg cat o2k day 1 raw 1 100 150 170 to list files 1 to 100 and 150 to 170 only This is relatively slow as each file has to be opened and the header in formation to be retrieved o Output will be an ASCII file with name list file lis and the following information one line per file file ident lt gt t NDIT baffle 2 bts 1 Filt 2 filt 3 read mode O2k 2003 09 11T7T22 17 01 000 fits F0001 fits DQE measurement K PRIME 0 8 5 NO OUT OPEN OPEN K PRIME double corr read O2k 2003 09 11T22 17 22 000 fits F0002 fits DQE measurement K PRIME 0 8 5 NO OUT OPEN OPEN K PRIME double corr read O2k 2003 09 11T22 17 39 000 fits F0003 fits DQE measurement K PRIME 0 8 5 NO OUT OPEN OPEN K PRIME double corr read 13 13 List FITS files on tape To list a FITS tape proceed as follows o Insert tape into drive on fire35 o cd disk a o2k tape listings o S PM fitslist 02 12 2008 13 01 74 OMEGA2000 manual doc Answer the questions and give OMEGA2k format as format file Please delete the listings you created there 75 02 12 2008 13 01 OMEGA2000 manual doc 14 Online data reduction pipeline General Remar
99. es AND manual focus settings were done in state off use the com mand wheel focus new to discard the saved last relative focus correction information and to update it with the current focus initialisation of wheels does not change the focus but activates the focus correction for the next wheel usage for initialisation the focus correction is still correct if no change of the focus logic were made xserver type USER syntax xserver xserver Set default X display X server name for stripchart and for the slave display 02 12 2008 13 01 124 OMEGA2000 manual doc Appendix 7 Recommended focus fields Finding charts are from red DSS II plates and are 20 on a side The dashed square indicates the field of view of OMEGA2000 Focus at 1h o J2000 0 55 12 33 6 J2000 24 55 05 gt E o b E vi E y x R dT o t E A a E e gt E 1 e 4 au e gt gt TRE ad i E H Au E v LJ E REN x BA A sl s 9 Pn re e hd ae e y Figure 50 Focus field at RA 1h A bright star in the neighbourhood produces a luminous arc in the field of view 125 02 12 2008 13 01 OMEGA2000 manual doc NGC 1647 52000 4 45 51 52 8 J2000 19 00 30 a E u 1 Ea EA ret PAE e ts 3 m E LI 1 LJ i b zi a ji D E e 4 z t Ak F E E P amp 3 r i ien a i
100. es this path for all relevant information Dither Pattern The standard dither pattern is shown in Figure 41 below The actual pattern consist of 20 dif ferent positions with typical relative offsets of 20 30 arcsecs After 20 images the telescope is moved back to the origin and this origin is then shifted according to the repetition pattern Figure 42 before the basic pattern is started again This way 400 different positions are de fined Figure 43 after which the pattern starts back at position 1 This also holds if the dither pattern is specified by a user supplied file Note The positions of the primary dither pattern are all within a square of 18 arcsecs from the origin the shifted origins for the repetition pattern are within a square 5 5 arcsecs from the origin Thus the maximal waste area at the edges where not all images overlap is 23 5 arcsecs on each side The effective central observing area where all images overlap is a minimum of 14 5x14 5 arcminutes for any number of dither positions used Please note that the waste area is not really lost If the same dither pattern is used for all pointings one may regard the whole mosaic as subjected to this dither pattern This however complicates data reduction considerably Autoguiding To initiate autoguiding an acquisition frame is to be taken manually Using o2k offseta reference star is defined whose position will then be checked after each dither position
101. est estimated focus in microns and focus offsets between two test exposures in mi crons number Total number of images for the focus analysis The input has to be a odd number lar ger than 3 If an even number is specified it will be converted to the next odd number itime total integration time per image single integra tion time Integration times in seconds The first number specifies the total integration time per image the second one the integration per single exposure which will be co added to yield one integrated image action action_flag graphics_output Two integers that specify the action taken and the feedback to the user action flag 07 all actions carried out image taking analysis best focus ad justment 1 do only image analysis no instrument and telescope commands sent 2 gt analyze images and adjust focus to the best setting 32 take images and analyze graphics output 0 show only final graph 1 gt show all graphs including the selection process 02 12 2008 13 01 OMEGA2000 manual doc P7 objects Approximate number of objects to be searched for and analyzed The default value of 40 is appropriate for fields with enough stars For sparse fields the parameter may be set to lower values P8 boxsize Total boxsize in arcseconds around objects for the objects analysis The default value should be working in most cases Internal The routine contains three internal parameters which are define
102. et is implemented which may cause the minimal integration time to be too long 1 line 1024 line 1 line 1024 line 1 line 1024 line 1 line 1024 line 1 line 1024 line Figure 25 The scheme of the multiple end point read The single pixel read The read out cycle starts a full frame reset line by line then only one pixel is read out per channel or quadrant according to the Four or Eight Output Mode Thus the data of a full channel or a quadrant consists of the value of only one arbitrarily chosen pixel This mode is only for engineering purpose 02 12 2008 13 01 24 OMEGA2000 manual doc 7 2 Optics The optics consisting of 4 lenses made of CaF fused silica FS BaF and ZnSe is achro matic between 850 and 2500nm The centre to corner image distortion 1s almost negligible 0 12 over a distance of more than 600 The image scale is 0 44962 pixel in H see also diploma thesis of Anke Kitzing MPIA 1 01 5 A A 1 01 557 5 E a MIDAS L 1 MIDAS J 025EP F 4 025EP Tue H J Roeser User H J Roeser 1 005 F 2 bles Neeser 1 005 H Table Mer refer 4 Columa xo q Yi Disthetio A 7 Sales E a JM 5 0064 2 ot bra ae NS Wi D OOOLEATT2 d T r bo E A E A II A tex AP s mo ae a Selection AL E DistRatia Ed 5 J Date 16 Mar 2008 Time 20 27 13 DistRatio 0 995 O 995 0 99 1 i 1 L 1 1 L 1 1 L 1 1 1 0 99 E oa gos 0 1 4 34 4
103. event pipeline reduction of the wrong data set itime tot pointing tot single single Integration times in seconds tot pointing is the total integration time for the pointing This parameter determines the final limiting magnitude of the pointing Tot pointing tot single images are take at different dither positions tot single is the time for one integrated image which is equivalent to the integration time at a one dither position Tot single single exposures are added up in memory be fore the final single image with an integration time of tot single seconds is saved on disk Single is the a single exposure integration time This parameter is to be optimized for each filter to allow background limited observations while being within the linear de tector regime Note To prevent truncation errors when calculating the number of repetitions tot pointing should be a multiple of tot single and tot single should be a multiple of single object identifier Character string for the IDENT descriptor If blanks are contained the string should 66 99 be enclosed in Start pos tel pos Starting position of the dither sequence This parameter allows the continuation of the dither pattern at a specified position after an interruption As a default the telescope is expected to be in the start pos 1 position tel pos PREV from where the dither pattern is continued with the next position If the current telescope position is t
104. f repeats On completion of a read the images are not saved unless autosave is selected under the save option Save The save button saves the most recent image s obtained using the currently defined save options _ EE zo Filename The name of the next file to be saved by pressing the SAVE button at the beginning of this line or by issuing next filename yo146_ a save command from a script One can either specify a from EI to E name or a root In the latter case the filename is the root area 1 1 2048 2048 plus a four digit integer which will be automatically in US crement by one each time a save is executed By specifying DEO the root the system looks for the highest free filename If a Hinaman Lol filename ends with a number this number will be increased FITS table i FT b Save Options Calls up a save configuration panel which atches defines the default way in which to save images The main dump Lol choices are whether to save individual exposures as sepa auto save 2 rate disk files or to integrate them sum and save only a immed save zl single disk file Note that the save options are overridden by any options specified in observing macros For example save f 2 i in a macro will integrate from image 2 to the end of the series and save only a single file even if the Figure 38 Save options window 35 02 12 2008 13 01 OMEGA2000 manual doc save options specify savin
105. field A start_pos 35 pointing 8 offsets 1 Take 2 second exposures and add them up in memory to 20 second integrated im ages The total integration time for the object is 1000 seconds The total integration time for a single sky image is set to 10 seconds thus five 2 second exposures are co added in memory for the sky The sky images are taken 10 arcmin away from the object at 8 different positions The dither pattern starts at position 35 with non integer pixel offsets the descriptor POINT_NO will contain the value 8 The name of the image catalogue created is field_A cat the descriptor IDENT of all images will contain field A 02 12 2008 13 01 68 OMEGA2000 manual doc o2k sky point help Help text Parameters external Compared to the macro for normal observations three additional parameters have to be speci fied for observations of extended objects the distance and direction of the designated sky field from the object and the integration time for a single sky exposure Pl P2 P4 P5 69 icatalog Name of image catalogue that contains a list of all taken images The name of the im age catalogue is automatically passed on to the pipeline and can be used for online data reduction If no online or further pipeline reduction is desired this parameter is just a dummy For online reductions the icatalog parameter should by specified with distinct names to prevent pipeline reduction of the wrong da
106. from visible wavelength CCDs in requiring special semiconductors with a smaller energy difference between the valence and conduction bands Typical materials include indium antimonide InSb platinum silicide PtSi and mercury cadmium telluride HgCdTe OMEGA2000 s detector is a HgCdTe device The figure below contains a schematic drawing of the Rockwell NICMOS3 infrared array in OMEGA2000 photons sapphire HgCdTe detector indium bumps qi E silicon multiplexer MUX Figure 4 Schematic structure of a HgCdTe HAWAII2 detector Photoelectrons are collected in the detector material and read out using a multiplexer Because silicon multiplexer technology is much more mature HgCdTe and InSb arrays are hybridized This means that the detector material is cold welded to a silicon multiplexer using a series of small indium bumps The actual HgCdTe detector material is grown on a sapphire substrate for mechanical strength This hybrid arrangement has the benefit of lower crosstalk and less blooming and streaking compared with visible wavelength CCD s Another significant advan tage of the hybrid is that it permits non destructive readouts of the detector in which the volt age on the pixels can be measured without affecting charge collection During the detector reset a constant voltage is applied to all pixels Incoming photons delib erating charge in the detector substrate reduce this voltage Saturation occurs if the voltage
107. g images separately Turning on auto save will execute a save after every read without clicking on the save button Test gives test as a root name for the next image which will not be saved to tape After the test exposure the previous file root name is restored Object is the object name which is written into the fits header under the keyword OBJECT for the current image It will be updated automatically if object selection is done through ob ject files recommended or can be changed by hand Sky Clicking on the sky button writes a sky flag into the fits header but otherwise has no effect Comment to be included in the FITS header Macro Here you specify a macro to be read into the macro buffer The filename without the mac extension is all that is necessary all macros must have the mac extension The macro file must be in the MACROS directory specified under the macro path in the options menu see above Please refer to Section 10 on page 45 for the macro syntax and commands Execute Pause and Abort control the execution of observing macros reads and running MIDAS prgs Note that if a pause or abort is issued the macro will continue executing until the current command is completed Check in the command window to be sure that the pause is in effect Clicking on continue will continue executing the macro after the pause This is useful when changing the dome slit segments In the case of a MIDAS prg running the abort
108. ger number of data points This can be achieved be editing the file 02K UTIL obs macros Tilt master tilt prg which combines the results from two tilt measurements Before it can be used a master tilt frame e g mas ter tilt bdf has to be created Functionality The tilt routine is determining the local focus position according to the algorithm described in 1 without the telescope and instrument parts The local deviation of the focus from the av erage over the field of view is plotted in an output frame 02 12 2008 13 01 62 OMEGA2000 manual doc 13 6 Taking dithered science frames Two different observing macros are provided One for dithered observations of sparse fields with sky determination from the science frames and a second macro for alternate ob servations of an extended object and a designated sky field 13 6 1 Survey observations Function Call o2k dither icatalog itime tot_pointing tot_single single object start_pos tel_pos pointing offsets autoguide Remark The actual routine is called dither pointing prg and can also be called by QQ O2K UTIL obs macros dither pointing Defaults icatalog no default itime no default object identitfier no default start pos 1 PREV start at first dither position telescope at n 1 pointing 1 pointing identification number for header offsets 0 use pixel integer offsets for the dither pattern autoguide no do not correct dither offsets f
109. ges in image catalogue 1 do summation only 1 e the input images are already reduced 2 do single image reduction only i e the images are not superimposed sum save flag Specifies what sum images are saved on disk 0 every updated sum is written to disk every n average images 1 only the final master sum is written to disk 2 the final sum and the real dirty without cosmics removal sum andthe difference of the two are written to disk Naming conventions of the sum images sum icat fits gt for the cosmics cleaned master sum image cut sum icat fits 2 for the cut out cosmics cleaned sum ave icat fits for the real dirty sum image dif icat fits gt for the difference image ave sum If intermediate summation results are saved on disk a prefix index is added except for first one 2 sum icat fits 3 sum icat fits the last of these frames is cut out e g cut 7 sum icat fits and always con tains the sum of all images LABEL sum P5 kappa sum Cosmics clipping parameter All values above median kappa sum sigma are clas sified as comics and removed kappa sum 1s a real number LABEL kappa sum P6 cuts min max 02 12 2008 13 01 78 OMEGA2000 manual doc Cuts for the final frames The descriptor LHCUTS is set to median min sigma me dian max sigmal LABEL cuts P7 flags sky save calibration position screen output Integer flags sky save determines whether the
110. gnated sky field Can be set to N S W E for a des ignated sky field North South West or East of the object If set to ALL 8 different sky positions located around the object at the specified distance are used object identifier 02 12 2008 13 01 P6 P7 P8 OMEGA2000 manual doc Character string for the IDENT descriptor If blanks are contained the string should be enclosed in gt start pos Start position of the dither sequence This parameter allows the continuation of the dither pattern at a specified position after an interruption The telescope is expected to be in the start pos 1 th position from where the dither pattern is continued with the next position pointing Identification integer for the descriptor POINT NO Can be used for easier data iden tification offsets Flag for dither offset mode offsets 0 gt the offsets will integer multiples of the pixel scale offsets 1 gt non integer offsets are used for the dither offsets offset name gt the offsets are specified in a file with this name This file is a plain ASCII file with AX AY in arcsec per line no blanks allowed The first line is a comment and exactly 20 offsets are required The offsets are relative to the previous position The standard repetition offsets see be low are used also in this case This file has to be located in the current path The standard mode should be integer offsets because it facilitates a later summation of
111. he field acquisition position Cel pos AQ then the telescope if offset to position start pos 1 before nominal operation offset to the desired starting position is resumed This is convenient if the previous sequence was aborted and the field had to acquisitioned again pointing Identification integer for the descriptor POINT NO Can be used for easier data iden tification 02 12 2008 13 01 64 OMEGA2000 manual doc P6 offsets Flag for dither offset mode offsets 0 gt the offsets will integer multiples of the pixel scale offsets 1 gt offsets in units of 1 3 of a pixel are used for the dither pattern This facili tates the use of drizzle to obtain super resolution in case of very good seeing offset my_foffsets gt the offsets are specified in a file with this myoffsets dith This file is a plain ASCII file with AX AY in arcsec per line no blanks allowed The first line is a comment and exactly 20 offsets are required The off sets are relative to the previous position The standard repetition offsets see below are used also in this case This file has to be located in the current path The standard mode should be integer offsets because it facilitates a later summation of several images by appropriate xy shifting P7 autoguide y n internal The keyword file path defined as the first keyword in the PRG contains the path information for the pipeline auxiliary files In online mode the pipeline search
112. ill be inclined in the adjacent image offset by esca with a parallactic mount of Aa cos 9 by an angle Ag This is illustrated in Figure BS 12 at right The rotation angle is Ag Axtan In case of OMEGA2000 this rotation will result in a misalignment of objects in two adjacent mosaic images If a stellar image at the border of the detector in X and in the centre in Y is assumed to be aligned in the two adjacent mosaic images an object in the upper lower corner would be misaligned by Ap 0 5x 2048 x tan Ag 1024 x tan 15 4 x tan pixels The following table provides the Ap values as a function of declination declination 9 0 10 20 30 40 50 60 70 80 Ap pixels 0 8 1 7 2 6 3 8 5 5 79 12 6 26 0 Table 2 Image rotation as a function of declination A differential effect in the same sense will also be created by dithering images see below 5 2 Background subtraction Traditionally the classical photometry consisted of measurements of the source in one aper ture and the neighbouring sky in another Then object and sky switched apertures and the pro cedure repeated With an FPA the sky still needs to be determined with sufficient accuracy to This is the difference between the angular distance of an object in the corner to an object in the centre calcu lated from the RA and DEC coordinates using spherical trigonometry and the di
113. ilter fits get gui help history hpmove idlemode init iniwindow interactive instrangle itime itype kill lamp last load logfile ls ls lyot macro median msio next object observer optics pause pipe pkginp polpos ptime put pwd quit read repeat resets rmode rottab rtime saad satcheck save set shminfo Sky Sleep sndwin sound status stripchart subwin sync system tO ti t2 tdebug te lescope telgui tempcontrol temphistory tempplot test trigger userstatus verbose version wheel xserver abort type USER syntax abort r k d m s t a b Aborts read and macro execution r abort read only d abort save of data only m abort macro only s abort sync only t abort test only a abort all processes above here b abort backup k 4 special option to kill read after waiting seconds df1t 2 First tries smooth kill via catchable signal then urge the kill Default no switches abort everything except save and backup On read abort the file geirsLstAbort is written to CAMIMP tmp and contains date and time of abort alarm type USER syntax alarm sound volume Play General Error sound You may enter a sound file but this file must be located in SCAMHOME SOUNDS volume range is from 1 to 100 aperture type USER syntax aperture name Move the aperture wheel to position name The named positions are defined in the file SCAMINFO wheel e
114. in the file name is the date and time the MIDAS procedure was started 02 12 2008 13 01 OMEGA2000 manual doc 13 6 2 Extended objects Function Call o2k sky point icatalog itime tot pointing tot single single tot single sky move direction object start pos pointing offsets Remark The actual routine called is sky pointing prg and this may also be called by O2K UTIL obs macros sky pointing Defaults icatalog no default itime no default move 30 sky position is at a distance of 30 arcmin from object direction all use 8 different sky positions around object object_identitfier no default start_pos 1 start at first dither position pointing 1 pointing identification number for header offsets 0 use pixel integer offsets for the dither pattern Examples o2k sky point M51 3600 30 5 20 N M51 in J 2 Take 5 second exposures and add them up in memory to 30 second integrated im ages The total integration time for the object is 3600 seconds The integration time for the sky observations is not specified thus the same values as for the object are used The sky images are taken 20 arcmin North of the object The dither pattern starts at the default start position the descriptor POINT NO will contain the value 2 The name of the image catalogue created is M51 cat the descriptor IDENT of all images will contain M51 in J o2k sky_point icat field_A itime 1000 20 2 10 move 10 direction ALL object
115. ions Tip tilt The four Serrurier trusses can be set individually to incline the front ring For OMEGA2000 all four focus readings have to be identical i e no tilt in the fronting You can check the cur rent position of the four trusses with the command ReadFocus in an xterm at the telescope control computer t35 Note OMEGA2000 has no auto guider and totally relies on telescope tracking Thus one should not run excessively long dither sequences It is recommended to re align the telescope after at least one hour of observing or use the auto guide feature in the observing macro 29 02 12 2008 13 01 OMEGA2000 manual doc 9 The graphical user interface GUI The software handles all infrared cameras at Calar Alto Therefore the observer once having used one system will easily feel at home with the other cameras Slight changes are intro duced only due to different hardware e g the number of filter wheels in the dewar 9 1 Login to the system At any one of the dual monitor X terminals you can log into the fire35 Please choose the CDE desktop at login User o2k Password ask Calar Alto staff The following panels will appear upon login on the otherwise empty screens Left monitor Figure 32 Control panels on the display after login as user 02k The central rectangular blue buttons labelled OMEGA2k and Pipeline on the left and General etc on the right hand screen are meant to select the appropriate de
116. ix 11 LINUX PC as X Terminal OMEGA2000 is operated most conveniently from a dual screen X terminal For this purpose we use a LINUX PC emulating an X terminal This way we ensure that we almost always do not run out of colours despite the use of MIDAS display netscape and acrobat etc To launch the terminal one has to log into the PC with the name o2klinux as follows User o2k Password ask staff same as on fire35 Once the linux desktop is available you launch the terminal emulation as follows X 1 vt08 query fire35 This connects directly to the fire35 You may also access other machines via the host chooser if you type instead X 1 vt08 indirect It is possible to toggle between the LINUX desktop and the X terminal with the function keys Alt F8 OMEGA2000 terminal Alt F7 LINUX destop To stop the additional xserver type killall X to kill it give an additional 9 On the LINUX PC besides the usual environment you will soon also have the possibility to work in a WINDOWS environment with Microsoft Office Furthermore a DVD burner is available to backup your data Figure 67 Dual screen X terminal to the right operates the camera The screen at left is for telescope operation 145 02 12 2008 13 01 OMEGA2000 manual doc Appendix 12 Basic MIDAS commands To use the observing utilities measuring seeing etc it is helpful to display a flatfielded im age Here are the basic steps for those not familiar with MIDAS
117. kes care of most of these changes during the night So the main task is finding an initial good focus This is accomplished by a focus test series during which the telescope focus position is systematically varied and the width of stellar images is meas ured for each of the focus settings Whereas with CCDs the whole series can be stored on a single frame with the charge shifted between the individual focus settings with infra red de tectors individual frames have to be taken for each focus setting due to the high background which requires short integrations We provide suitable focus fields Appendix 7 and supply a procedure to take a focus series analyse the width of the stellar images as a function of focus value and set the best telescope focus see Section 13 1 6 2 Flat fielding Each pixel of a FPA has a slightly different quantum efficiency than its neighbours Further more there are larger scale variations of the quantum efficiency across the detector To com plicate matters further the quantum efficiency is a function of the wavelength of the incident radiation Thus flatfields need to be taken for all filters in use during the observing campaign Vignetting due to the optics and dusk on optical elements produce effects which are similar to the variations in quantum efficiency Illuminating the detector homogenously will not pro duce a constant signal on the FPA Flat fielding is the process to correct for all these effects and p
118. ks e The OMEGA2000 pipeline is a MIDAS application program written in C which is called from a MIDAS procedures Thus an active MIDAS session is required and the context omega2k ctx has to be set for the definition of the utility short cut com mands o2k command e Several pipeline parts use the environment variable O2K_UTIL which points to the directory o2k utilities All paths are defined relative from this top level directory e The pipeline was written by Ren Fafbender A detailed description is given in his di ploma thesis available as a PDF file together with this manual Function Call o2k pipeline image cat frames sky mode sum kappa sum cuts flags flatfiels Remark o2k pipeline is an OMEGA2000 context command which calls the routine OMEGA pipeline prg The pipeline can also be called without the context command in the following way O2K UTIL pipeline PRGs OMEGA pipeline Defaults icat automatic use image catalogue created by current observing macro session frames 3 use 3 image on either side of a masterframe for the sky determi nation 1 e determine sky from a total of 7 images mode 2 5 outlier clipping mode with x 5 sum 5 0 1 n average action flag sum save flag Use 5 images for the sum reference frame determination do single image reduction summation write out only final sum frame kappa sum 10 eliminate all cosmics that are above a 10 sigma cutoff cuts
119. kup program e g gt cd disk a max gt tar cvf dev rmt 0 29nov96 syntax backup abort Aborts a running backup batching type USER syntax batching n Switches the batching size for GEIRS package streams to number n 1 Without argument the current status is shown buffers type USER 101 02 12 2008 13 01 syntax buffer fauto manual OMEGA2000 manual doc Switch auto update manual update of buffers If in auto mode after every read all data is automatically added to the appropriate buffer main offset position of UKIRT syntax buffer update This command adds the images of the last read to the main offset telescope position buffers If the data is already up to date the software will send an error message syntax buffer clear Clear main offset buffers All buffer commands are availale with Max UKIRT only cassoff type USER syntax cassoff angle Sets angle as the cassegrain angle for the NSEW orientation zero point casspos type USER syntax casspos angle Sets angle as the actual cassegrain angle Just a FITS header entry Without parameter the actual cassegrain angle relative to NSEW will be printed This is actual cass angle cassoff This value is written into the FITS headers as CASSPOS cd type USER syntax cd directory Changes directory for save operations UNIX
120. l processes including the waits on neither process process macro only waits for the process given time or 2 seconds for default system type USER syntax system comd Executes any system command where cmd might be any combination of arguments On problems with special characters surround the cmd with the character Example System tvgcmd 0 X033 to send escape to tv guider system tvgomd to get information about tvgcmd Waits for termination of the system call to type ENG syntax tO 4 Set timer 0 to milliseconds IRL electronics only tl type ENG syntax t1 Set timer 0 to f milliseconds IRL electronics only t2 type ENG syntax t2 Set timer 0 to milliseconds IRL electronics with Max Omega only tdebug type USER syntax tdebug text anytext anytext Writes an entry into the debug_S user log file in the form 2004 05 28 11 23 41 3794 ZD ocass typed 02 12 2008 13 01 logentry all what you 120 OMEGA2000 manual doc telescope type syntax USER tele scope abs solute hr min sec dg min sec equinox Moves the telescope to the absolute position alpha hr min sec delta dg min sec tele abs must not be used within a macro syntax tele scope rel ative zero or dalpha ddelta Moves the telescope dalpha ddelta arc seconds tele rel ze
121. latfields for the most commonly used filters during the commissioning phase Then the flatfields taken by the observer during the run are only need to correct only the pixel to pixel sensitivity variations and changes in vignetting due e g moving dust specks The central issue in flatfielding nevertheless is to illuminate the detector in a homogeneous way Creating such a homogenous illumination is not trivial Several types of flat fields are commonly in use 17 02 12 2008 13 01 OMEGA2000 manual doc 6 2 1 Sky flats The twilight sky is often used in CCD astronomy to take flatfield images In principle this is also possible in the near infrared range But depending on sky conditions and the field of view of the detector the sky brightness might vary across the FOV prohibiting a good flatfield im age Currently we have no direct experience in this respect with OMEGA2000 The same is true for the median filtered science exposures which are devoid of object signal 1f the images were dithered However again here variations in sky background and S N considerations are a major obstacle using these data as flatfields One can however hope that if sufficiently many science frames are averaged the sky variations are averaging out A procedure to take twilight flats is described in Section 13 3 6 2 2 Dome flats Homogenous illumination of a flatfield screen in the dome eliminates the above mentioned shortcomings However the homogenous illumi
122. ly with the square root of the integration time If the measuring aperture is adjusted to the seeing then for stellar images in the background limited case the exposure time increases with the seeing squared if aiming at a constant S N 2 5 are E N F background S N ratio integration time Figure 11 Signal to noise ratio as a function of integration time For narrow band imaging a detailed knowledge of the exact filter transmission and the loca tion and strengths of OH emission lines within the filter range is mandatory 02 12 2008 13 01 14 OMEGA2000 manual doc Imaging strategies With OMEGA2000 the standard observing goal is to survey a large area on the sky in one or more filters For this type of observations the main challenges are field coverage and back ground subtraction 5 1 Mosaicing a field Covering a large area on the sky with a detector of lim ited field of view FOV poses two problems Image distortion due to imperfect optics and field rotation due to the telescope mounting in our case the parallactic mount of the 3 5m telescope For OMEGA2000 the quality of the optics is excellent with a centre to corner distortion of 0 12 only Fur thermore no chromatic effects are measurable Field rotation is unavoidable Assume two objects with same RA are located on the central detector column in one image Then the vector connecting these two objects Figure 12 Field orientation in a mosaic of w
123. lysing a histogram of the slope values found For the dark series the slope gives the dark sig nal per second This analysis takes the following steps further documentation see header of prg file e Take the series either dark or flat e Create an image catalogue o forexample create icat raw XXX fits e bias extrapolation root frame list o forexample bias extr test raw 1 4 8 12 e Analyse the output frames o root const bdf o root slope bdf o root rms bdf 73 02 12 2008 13 01 OMEGA2000 manual doc 13 11 Monitoring atmospheric transmission o2k transmon magnitude filter By comparing the observed counts from a star of known brightness e g from the 2MASS catalogue with the theoretically expected counts one can get a feeling for the amount of at mospheric absorption or at least about variations of it The acquisition frame is most conven iently used for this purpose as usually the brightness of the alignment star is known The procedure uses a simple approach in that the user places the cursor box around the object of her his choice and second into the local background The observed count rate 1s calculated from the difference of the two background is scaled by differences in box size The ratio of measured to expected count rate is written to the log file Transmission log in the cur rent directory If the star selected is saturated the calculation is aborted and an error message is issued Currently only the filt
124. mmand not needed for standard operations SUPER system safety critical commands A password is required to use such a command the observer s name has to be the password Parameters in are optional List of exclusive values are enclosed in syntax help x Starts a HTML browser and loads the camera software documentation history type USER syntax history Prints the command history syntax Repeats the last command syntax abc Repeats the last command that starts with abc hpmove type ENG syntax hpmove x y 107 02 12 2008 13 01 Move HP plotter OMEGA2000 manual doc idlemode type USER syntax idlemode action threshold Selects the used idlemode default norma Without parameters it shows the idlemode Option action break interrupts id start the goes seamle to clockin uses a integ decide for wait auto Option threshold lly float value of integration time auto with 2secs status le clocking to next read immediately ss from idle clocking g of read out time threshold to one of the above actions Below lse idlemode break that value idlemode wait is used init type syntax USER init camera name o optics s statu Initialize the camera Valid camera na in CAMHOME src camera h If no name is given the current setti camera BlueMagic BlackMagic Max128 Max OmegaPrime MPIA OmegaCass IRL O o
125. mment on an wavelength dependence of the linearity non linearity 6 6 Astrometric calibration The image scale in arcsec pixel and the image distortion of the camera has been measured during the commissioning runs see Section 7 2 These should remain fixed for the future However the orientation of the detector s Y axis may change slightly when the instrument was dismounted or especially if for any reasons the detector had to be removed To easily check the astrometric properties we supply a list of astrometric fields with a sufficient number of astrometric reference stars from the M2000 catalogue Rapaport Le Campion et al 2001 These are listed in Appendix 8 where finding charts marking the stars from the M2000 cata logue as well as copies from the DSS are provided Elevation charts facilitate selection of a suitable field throughout the year Tables of these stars as well as a subset with proper mo tions from the UCAC2 catalogue are provided on fire35 as html files in the MANUAL path Pixel scale is 0 447312 0 000003 pixel in the Ks filter no blocking filter used Please note Due to the additional blocking filter needed for some filters the image scale is changed for these filters by approximately 2 5 1000 More information may be found in the Diploma thesis of Anke Kitzing 2006 6 7 Photometric calibration For a rough photometric calibration we provide the expected counts in all the filters for a 0 magnitude star in
126. mmunication to the telescope clobber type USER syntax clobber yes no on off Enables disables overwriting existing files Default is no coadds type USER syntax coadds t or subreps skips 103 Sets 4 of coadds For Midi 4 of coadds of skips is identical with of subrep sub repeats done by ROE At saving time coadds are coadded to a single crep image Option skips defines the first skips of subreps to be thrown away Option t is used without other arguments and just checks the last coadd and itime command if the values has to be adjusted according to possible combinations of coadds and minimal sub integration If there are adjustment found a warning is given Without option the current state is shown coadds 1 sub skip 6 wanted coadds 9 which informs that the last subrep count set was 9 but the last efficient integration time to use were to small and only single coadd read instead of 3 reads fits additional to the 6 skipped into that efficient integration time Attention For Midi the itime as effective itime of a coadded image is hold constant when coadds command or itype command is used This will perhaps first adjust the coadd value automatically to smaller values or and than adjust the subitime value to larger values 02 12 2008 13 01 OMEGA2000 manual doc available for Midi as SW coadding with skipping option th of the values are
127. mp x a u 2 gts E E a h m n LI c n E oT Y E Li i et x 1 i z E r x x L a a ALIA he 7 gt a ds att Eod 31 ya 1 Y an i es 2 Figure 59 Astrometry field at RA 5h finding chart for astrometric stars from M2000 135 02 12 2008 13 01 OMEGA2000 manual doc Astrometry 9h M67 11 89 11 84 DEC 4 Figure 60 Astrometry field at RA 9h finding chart for astrometric stars from M2000 02 12 2008 13 01 136 OMEGA2000 manual doc Astrometry 13h A 17 85 17 80 17 75 DEC 9 17 70 17 65 17 60 13 287 13 282 13 277 13 272 13 267 RA h Figure 61 Astrometry field at RA 13h finding chart for astrometric stars from M2000 137 02 12 2008 13 01 OMEGA2000 manual doc Astrometry 13h B 12 70 12 65 12 60 5 O Ww a 12 55 12 50 12 45 13 080 13 075 13 070 13 065 13 060 RA h F T i gt M ri 5 i 2 r Li i E m t 1 i m e i T E P T x a ace yi L3 n pS LI E Figure 62 Astrometry field at RA 13h finding chart for astrometric stars from M2000 02 12 2008 13 01 138 OMEGA2000 manual doc Astrometry 18h 14 78 14 73 14 68 DEC 7 14 63 14 58 14 53 17 707 17 702 17 697 17 692 Uu aa 13 ae Dele AA oe Se ee ie n r r i dije ig Ar st WA
128. much quicker Perhaps the technique of the line inter laced read can guarantee the most stable operation of the image sensor because each line in the frame is read out twice before and after the integration As it can be seen all the lines of pixels in the adjacent readout cycles are interlaced in contrast to the previous modes where each readout cycle carries out a complete readout process This readout mode is also available for scientific purpose 1 readout cycle 2 readout cycle Read Reset Read Read Reset Read Integration Read Reset Read Read Reset Read Integration 1 line 1 line 1 line 1024 line 1024 line 1024 line 1 line 1 line 1 line 1024 line 1024 line 1024 line Figure 23 The scheme of the line interlaced read row time Figure 24 Alternate representation of the line interlaced read Multiple End point Read This read out mode is similar to the double correlated read but here the readout cycle contains 2 x n readouts instead of two After the complete frame reset the full array is read out n times and the average of the n frames provide the bias values of the pixels after reset After the inte gration the complete array is read out n times again and the average of these frames is taken as the integrated signal Figure 25 The video signal is the difference of the two averaged frames Although this readout mode allows a stable operation the duration of one readout cy cle is in order of seconds even if a fast res
129. n FWHM vs intensity plot with the used cutoffs 3 The FWHM histogram of the objects selected 4 The final plot with the x and y focus parabola and values for the best focus and the seeing This plot is automatically saved as ps file with the filename corresponding to the name of the masterframe The first three graphs may be suppressed be setting the graphics output flag to 0 Interelty plut oF 31 ctupcta w ILE QUIS o a 2 a 4 5 o La sx 201 20 Le 40 LR MAJA clio ld Coca JUHT Criar lt Seeing 1 109 erceec Focus 24356 3 O 240 3260 2400 Gem 72600 Taco Z6 Ti sump Position llorona 02 12 2008 13 01 60 OMEGA2000 manual doc 13 5 Tip Tilt Determination The tip tilt determination routine is based on an old version of the omega focus routine and needs some preparation steps before it can be properly used Since the detector tip tilt is only determined a few times and is not a general user task the routine is not optimized for user friendliness The different steps for obtaining a local focus mask are Preparation e The tilt routine does not take images Focus images have to be taken with the normal o mega focus routine described in Section 13 1 e The fits focus images have to be converted into odf format with filenames consisting of a 5 character root name and a 3 digit index e g focus001 bdf or foc K097 bdf The relevant images have to have consecutive indices The conversion can be done be editing th
130. nation of the screen is not easy and often the flatfield lamps are too bright Due to the dome geometry it is also sometimes difficult to not illuminate parts of the telescope structure which should be avoided to prohibit scattering light into the light path A big advantage of domeflats is that one can use the amble time in the af ternoon to take the flats Thus S N is normally not an issue To eliminate the thermal emission of the screen and dome surroundings one has to take flatfields in pairs with lamp on and lamp off The actual flatfield is then the difference image lamp on lamp off This at the same time eliminates any dark count signal from the detector A procedure to take well illuminated dome flats is described in Section 13 2 6 3 Dark current Even if covered by a cold aluminium blank in the filter wheel pixels may show a time de pendent signal the dark current Most pixel are well behaved in that their dark current is neg ligible or scales with exposure time Fore these the dark current can be modelled and sub tracted We provide two files which give constant and slope of a linear fit to the dark signal as a function of time to correct for this see Section 13 10 on page 73 for a MIDAS utility to create these files from a series of dark exposures Again care has to be taken not to destroy the S N of the science frames by a bad dark frame with insufficient S N All pixels not following a linear relation between exposure time a
131. nd dark signal are treated as bad pixels and are represented in the bad pixel mask 6 4 Bad pixel mask Dead pixels or pixels with an uncorrectable dark current hot pixels have to be interpolated from the neighbouring good pixels To facilitate this we provide a bad pixel mask whose pixel values of 0 indicate good those of 1 bad pixels The mask was derived from the dark current analysis by an appropriate cut in the goodness of fit of the linear relation between dark current and exposure time The same was done for a series of dome flats Both series were analyzed with the MIDAS procedure bias extrapolation described on page 73 6 5 Linearity Exposing a detector pixel to twice the number of photons should result in an exactly dupli cated recorded signal This is however not strictly true in general Each pixel may behave slightly non linear We have measured the linearity of FPA 77 Using the thermal emission of the front cover and controlling the exposure level via the exact exposure time we have fitted the signal as a function of exposure time for each pixel with a parabola see MIDAS procedure 02 12 2008 13 01 18 OMEGA2000 manual doc bias extrapolation on page 73 For each coefficient we have created an image whose pixel value specifies the coefficient for this pixel Using these frames any non linearity can be investigated Details are given in Appendix 3 We have not yet done this for different filters Thus we cannot co
132. neously illuminated image is show at right where the median pixel value is at about 250 The corresponding two dimensional sensitivity map is given below We summarize the main detector characteristics in Appendix 3 1 5 105 1 0 105 Frequency 50000 ESO e Rockwell ao Hawar FPA 77 fi 800 1000 1200 1400 1600 1 amp 0 2000 2200 2400 2000 o 100 200 300 kas wavelength nm Pixel value slope cts secl Figure 15 Quantum efficiency of a HAWAII 2 detector as a function of wavelength left The ESO data are from a different detector Finger 2002 the Rockwell data are from a detector dotted similarly to FPA 77 which unfortunately was not measured The adopted DQE curve for FPA 77 is shown in red Histogram of quantum efficiency across the detector for FPA 37 right The read out noise for a double correlated read i e two reads for a single image is 17 e The detector is clocked with a rate of 320 kHz resulting in a minimum integration time of 02 12 2008 13 01 20 OMEGA2000 manual doc 2048 x 2048 pixels 2 images 32 channels 320 kHz 0 80 sec The conversion factor from counts to electrons EPC electrons per count has been deter mined for all 32 channels separately The average is 4 42 0 06 for FPA 48 Lucifer detec tor used in 2003 and 4 87 0 05 for FPAT7 the detector in use since April 2004 Details can be found in the PhD thesis of Zoltan
133. noise 3 2 3 Multiple end point sampling ull reads Figure 9 Read out mode multiple end point sampling This mode is not implemented in OMEGA2000 This variant of Double Correlated Sampling is also known as Fowler sampling see Fowler and Gatley 1991 The array is read multiple times after the initial reset and before the final reset This scheme can reduce the read noise substantially theoretically by a factor JN In practice however amplifier glow and other effects limit the This mode is recommended in low background applications 3 2 4 Sample up the ramp Figure 10 Readout mode sample up the ramp This mode is not implemented in OMEGA2000 This readout scheme also reduces the effective read noise since the pixel voltage is sampled N times at equal intervals during the integration The total signal comes from a linear fit through the measurements ctype ramp or from saving the differences between adjacent reads ctype speckle The latter is used for speckle interferometry since the observer can save these adjacent differences as separate frames each of which is a rapid exposure on the sky Warn ing Be careful not to saturate the total signal in this mode This can happen easily when ob serving lunar occultations for example You may have to settle for a shorter sequence More details about the read out modes are given in the PhD thesis of Zoltan Kov cs 2006 13 02 12 2008 13 01 OMEGA2000 manu
134. normally be left at double correlated read called o2dcr or rrr IT s is the integration time in seconds Note that the minimum exposure time with Omega2000 is 0 8 seconds except for mode lir where it is 1 6sec Keep this in mind when doing broad band observations under high background conditions or when observing bright objects the array can easily saturate during these 0 8 seconds of dead time while the array is resetting cycT s is the total time for one read cycle in seconds Read Resets is the number of reads and resets executed in the current read cycle ieff elapse time gives the observing efficiency as the ratio of integration time to elapse time seff elapse time gives the system efficiency as the ratio of time for read out to elapse time Repeat is the number of images N with the specified exposure time T which will be taken each time a read is executed read cycle The total exposure time will then be N x T seconds The maximum number of images depends on the setup of the computer memory It is cur rently 23 images The current sequence number of the reads is displayed to the left READ button see below Endless may be pressed to start an endless loop of reads The images are read out with the current integration time and dumped to the display but are not saved This is useful for positioning the telescope before e g starting a macro Read The read button executes a read using the current exposure time and number o
135. ntegration time sec is written in front of the median Options stdout stderr delivers to the according data stream only the resulting value numbers r aw does not take the single image resulting normally from the read out mode but all single frames of the image for the calculation Example median of 2 images in the buffer median 1 2004 median 2 2003 ave medians 2003 50 Example median raw of 2 double corr images in the buffer median 1 1004 2007 median 2 1003 2001 ave medians 1003 50 2004 00 where with the stdout or stderr only the resulting 2003 50 or 1003 50 2004 00 is delivered to the according datastream msio type ENG syntax msio drive command 3000 Sends command to motor drive drive prvileged command This command is used for test with the wheels command uses the syntax of the motor drives e g move 10 moves the motor 10 steps move 20 moves the motor 20 steps pos 9000 moves the motor to the absolute position 9000 ver p returns the absolute position in motor steps drive 1 lower filter 2 lyot stop 3 upper filter 4 aperture OmegaCass commands e g Ups status of switches and home switch PR absolut position or position since power on D3000 3G 3CR moves motor3 3000 steps or to absolute position and waits on end of execution optics pol grism lyot filter 2 trlter i aperture drive Nu BB 0
136. o prepare your copies with tar This is not recommended however as tar is rather unsafe as it copies everything as one single file Also later access to a single file is much more complicated than with FITS tapes where images are stored as indi vidual files 43 02 12 2008 13 01 OMEGA2000 manual doc As long as the DAT Spooler is not able to write to two DAT drives at the same time we rec ommend to make a security copy of your data with Calar Alto s fitscopyx utility Your intermediate results e g from the pipeline can either be copied to tape with the DA Tspooler see Using the spooler from an xterm on page 95 for instructions on how to manu ally copy files or you may transfer them to 02k1inux and burn it on a DVD or CDROM there 9 7 Object catalogues You can create your own object list in the following format Object name Alpha Delta Equinox pm A pm D mag Comment Example HD 225023 0 00 11 8 35 32 14 0 1950 0 0000 0 004 6 96 J 7 97 G158 27 0 04 12 0 7 47 54 0 1950 0 056 1 85 7 43 J 9 31 HD 1160 0 13 23 1 3 58 24 0 1950 0 006 0 013 7 04 J 7 06 HD 3029 0 31 02 3 20 09 30 0 1950 0 0001 0 011 7 09 J 7 25 Gli 305 5 2238207 06 0258 570 X9359 9 amp eX HD 18881 3 00 20 5 38 12 53 0 1950 0 0001 0 030 7 14 227 12 Note The line character is used as a separator between fields If you don t want to put in numbers in some fields you still have to use a character as a place holde
137. o zoom To measure the seeing in a frame proceed as follows e Select the quicklook desktop e Load a flat fielded image into the display at appropriate scale e Execute o2k seeing e Selecta region in the display with the crosshair cursor left mouse click o Regionis displayed in zoom window e Adjust cursor box size in zoom window with arrow keys o Hint hitting 1 9 speeds up cursor movement Mark stellar objects with left mouse button To go back to the display window click right mouse button in zoom window Select next region Exit with right mouse click from display window The seeing values are appended to file Seeing 1log in the current directory The individual measurements for the current call are stored in table seeing tbl which is overwritten with each new call to this procedure Saturated images are skipped in calculating the seeing 13 8 Pixel accurate alignment of the telescope o2k offset dest X dest y To offset the telescope in order to put a star onto a given pixel proceed as follows e Select the quicklook desktop e Load a flat fielded acquisition image into the display e o2k offset dest_x dest_y o coordinates are in pixels e Mark star whose position is used for alignment with cursor box o This determines the star s centroid via center gauss e Offset coordinates are displayed e Execute by giving a if okay or h if you need to abort or adjust e Check via new acquisition frame optional The telescop
138. ola to the data Determine the minimum and thus optimum focus O 0 0 0 OO The MIDAS command regression table will be helpful if you put your measurements into a MIDAS table with the MIDAS table editor edit tab 02 12 2008 13 01 58 OMEGA2000 manual doc Functionality The following flow chart demonstrates the principal structure of the focus routine OMEGA2000 FOCUS ROUTINE Setup Help Text parameters amp keywords Take Images with different telescope focus positions Find Objects in Master Frame retum x y position object classification Stellar Object Selection 1 crude selection of objects that were classified as stellar 2 remove objects that are too close to frame edge 3 remove objects that are saturated 4 vefined removal of remaining galaxies and cosmics Loop Over All Images determine x amp y EWHM of selected objects in image take average of all x amp y FWHM in each image Fit Parabola to FWHM focus Data Points and Deterinine Minimuin Display Results Focus Telescope 59 02 12 2008 13 01 OMEGA2000 manual doc Before the parabola is fitted the deviations between FWHM in X and Y are analysed Points who differ in FWHM between the two axis by more than 2 50 of the difference distribution are discarded in the fit Graphics output A total of 4 graphs is plotted during the object analysis process 1 A x and y FWHM histogram of all found objects 2 A
139. on thus this work The standards for which these finding charts are provided come from the UKIRT Faint Infrared Standards list of Casali 1992 JCMT UKIRT Newsletter 4 33 and this is the source for most of the data which appears in the following table The only new material here are the finding charts themselves and perhaps the packaging The finding charts on the following pages were obtained through K filters with the MAGIC and Q infrared cameras at the Calar Alto 2 2m and 3 5m telescopes over the course of two years of observing In several cases identification of the field from Palomar Observatory Sky Survey POSS images was not so straightforward the intrinsic colors of the stars can significantly alter the relative brightness of the different stars in any given field of view In addition proper motions can change the relative positions over the 50 years since the first POSS was produced It is hoped that these finding charts will thus be useful to the infrared observers David Thompson 19 February 1997 Cover This image of FS16 and FS17 shows the field of view of the Q camera on the Calar Alto 3 5m telescope 6 8 arcminutes square produced from five offset 5 second images UKIRT Faint IR Standard Stars FSO1 FS02 FS03 FS04 FS05 FS06 FS07 FSos FSog FS10 FS11 FS12 FS13 FS14 FS15 FS16 FS17 FS18 FS19 FS20 FS21 FS33 FS23 FS24 FS25 FS26 FS27 FS28 FS35 FS34 FS29 FS30 FS31 FS32
140. or telescope drifts Examples o2k dither QSO_H 3600 30 5 quasar at z 1 5 4 Take 5 second exposures and add them up in memory to 30 second integrated images The total integration time is 3600 seconds The dither pattern starts at the default start position the descriptor POINT NO will contain the value 4 The name of the image catalogue created is OSO H cat the descriptor IDENT of all images will contain quasar at z 1 5 o2k dither icat field A itime 1000 20 2 object field A start pos 35 AQ pointing 8 offsets 1 Take 2 second exposures and add them up in memory to 20 second integrated images The total integration time is 1000 seconds The dither pattern continues at position 35 with non integer dither offsets Telescope is at the acquisition position The descriptor POINT NO will contain the value 8 The name of the image catalogue created is field A cat the descriptor IDENT of all images will contain field A o2k dither help Help text 63 02 12 2008 13 01 OMEGA2000 manual doc Parameters external Pl P2 P3 P4 P5 icatalog Name of image catalogue that contains a list of all taken images The name of the im age catalogue is automatically passed on to the pipeline and can be used for online data reduction If no online or further pipeline reduction is desired this parameter is just a dummy For online reductions the icatalog parameter should by specified with distinct names to pr
141. orner of the image gives a scale reference Zooming the display in or out is done with the two arrow buttons in the upper right corner of the window Stars can be selected by clicking on the image with additional information SAO number spectral type and visual magnitude appearing at the bottom of the window The coordinates can be sent to the telescope computer with the Move button A log of all previous exposures is kept displayed as green squares on the SAO map This feature is useful for following the progress of observing macros Clear Frames will clear the display of the old frames though future frames will continue to be displayed 02 12 2008 13 01 40 OMEGA2000 manual doc The SAOmap can be turned off by reselecting the SAO map option in the file menu of the telescope control panel Using the quit option in the xwindows menu will also kill the tele scope control panel 9 3 5 Air Mass Window The airmass window graphically displays the airmass of M the currently selected object red dot as well as a trac ing of the airmass over several hours of time blue line The number of hours depends of the width of the win dow This feature is particularly useful when used in conjunction with object files Objects selected and set from an object file will show their current airmass in the airmass window The airmass plot will automati cally reset to the current telescope position whenever the GUI queries the telescope computer
142. osition names and the actual one lyot is a background process and should have a sync after it when used in a macro macro type USER syntax macro c lear filename Executes the macro filename If c clear option is given alone the last macroname is just cleared This macro file contains commands like you use with the shell Be careful when invoking commands like read telescope or filter that run in the background Make sure that the next command does not conflict with the previous or use the sync command The default directory for the macros is SHOME If you want to start the macro test mac in S HOME macros then enter macro macros test mac It is posible to write comments into your macros using a semi colon The lines are truncated at the point where the first was found before the line is executed If the first character in a line is a this line will not be executed median type ENG syntax median r aw stdout or stderr nl n2 xl yl x2 y2 Calculates the median of images nl through n2 Default is all images The options starting with have to be the first parameters before the images nX or the areas xX Optional you might using the subarray xl yl x2 y2 parameter only Attention using the wrong area in subarray images the behaviour is unspecified 111 02 12 2008 13 01 OMEGA2000 manual doc It appends the result to the file SCAMTMP median log where additionally the i
143. pci ey Th Ts EP TAN r T Era UAM T z1 lc k E ja j FE e E A a a yi i Soa ice p zi En HE 2 ya E E a n kr ae i E DU hi z d x s E Y i z bi ttd K xj ji 1s d za T 2 a ie z s J n IET x i A LI z Figure 64 Astrometry field at RA 22h finding chart for astrometric stars from M2000 02 12 2008 13 01 140 OMEGA2000 manual doc January Elevation of astrometry fields M67 Astro 22h 90 80 Astro 05h 70 Astro 02h 60 Astro 13h 50 A o Astro 13h 40 B 30 Astro 18h 20 10 0 18 00 19 00 20 00 21 00 22 00 23 00 0 00 1 00 2 00 3 00 4 00 5 00 6 00 UT moon April Elevation of astrometry fields M67 Astro 22h 90 80 Astro 05h Astro 02h Astro 13h A Astro 13h B Astro 18h 19 00 20 00 21 00 22 00 23 00 0 00 1 00 2 00 3 00 4 00 5 00 UT moon Figure 65 Elevation plots for the astrometry fields January and April 141 02 12 2008 13 01 July OMEGA2000 manual doc 90 80 Elevation of astrometry fields 22 00 23 00 2 00 M67 Astro 22h Astro 05h Astro 02h Astro 13h A Astro 13h B Astro 18h October Elevation of astrometry fields 19 00 20 00 21 00 22 00 23 00 0 00 UT M67 Astro
144. ptics wide high very side down status offline online motors offline camera direct temperature controller offline 0 S m t syntax init telescope name f number s st s m status t status mes and optics are defined ngs are used and checked 256 0megaPrime IRL megaCass_MPIA camera direct atus Initialize the telescop Valid telesc are defined in CAMHOME src camera h lab ca35 ca22 cal2 hd07 ukirt focal ratio 3 8 10 25 35 45 status offline EPICS serial telescope Es s syntax init wheels Read to filter apertur wheel database the ZERO position ope names and focal ratios and move wheels detent position iniwindow type USER syntax iniwin Dp F pa camera tel OK be Opens a window to setup th If you leave the window using the the telescope and the wheels will i Scope configuration putton the camera nitialized if their setup was changed all forces a complete re initializat anything was changed ion whether or not interactive 02 12 2008 13 01 108 OMEGA2000 manual doc type syntax ENG interactive on off yes no If you use the interactive mode the outputs are blocked after 19 lines until you enter RETURN Default is yes All shell outputs are blocking if you use interactive yes and you may lose messages if you set interactive no
145. r Important e f you have negative declination less than one degree then you must place the negative sign before the minutes e g 0 13 45 6 e The required fields are Name Alpha Delta Equinox e The optional fields are pm A pm D mag Comment e pm A and pm D are in units of arcsec century e All object list files must have the extension obj Some useful catalogues focus fields etc are found under disk a o2k OBJECT_CATs The current catalogues are focus_fields astro_ fields faintstd arnica Please note For the time being the equinox in the catalogue and the one set in the telescope GUI have to be the same Otherwise the telescope will not position properly 02 12 2008 13 01 44 OMEGA2000 manual doc 10 Macros You can prepare macro files in advance to carry out specific normally reoccurring tasks Please note that the macro utility is sequentially oriented Ze you have to specify a macro command for every action you normally would take at the camera GUI It does not provide conditional and loop capabilities However every macro command may be issued with the prefix cmd 02000 from a shell e g a MIDAS procedure the utilities presented in Section 12 make heavy use of this feature The following example shows a simple macro that moves a star to five positions on the detec tor starts a read at each and saves the data Example read start the lst read sync wait until all previous comm
146. r are meant to increase the efficiency in the use of tele scope time OMEGA2000 has the same functionality in terms of user interface and macros as the other IR cameras on Calar Alto Thus users may use their own observing macros All functions described in this chapter are MIDAS procedures and have to be called from an active MIDAS session The context omega2k ctx has to be set for the definition of the utility short cut commands o2k command All routines use the environment variable O2K UTIL which points to the directory o2k utilities All paths are defined relative from this top level directory All routines can be paused during the data acquisition process by pushing the PAUSE button in the instrument GUI The data acquisition is continued by pushing the CONTINUE button All routines can be aborted during the data acquisition process be pushing the ABORT button in the instrument GUI The routines check after every image whether the data acquisition has been aborted i e it can take up to a full integration time before the macro is actually aborted During data acquisition the macros should only be terminated using the ABORT button Ctrl C would possibly cause instrumentation problems Outside a MIDAS procedure Ctrl C can be used to abort the current MIDAS command This might however close your MIDAS ses sion and also close the X terminal In this case just launch the session again If MIDAS com plains about an already open session proc
147. replace italics with actual names values Creating a normalized flatfield statistic filename fits displays the information on the frame statistics compute flat filename fits median Use the median from the statistics command to normalize your image Output will be in BDF format Flatfielding an image compute test filename fits flat Display image on the screen load test sc 2 ce 1320 912 cuts 3500 7500 This will display frame test with scale 2 centred on pixel 1320 912 The lower and upper display levels cuts are at 3500 and 7500 respectively This assumes the im age to be in BDF format see below To set the cut levels in terms of local sigma values use back det This command displays the cursor box which should be placed in a region of clean background no stars no bad pixels The cuts are then calculated as median 3o median 100 default To set to other sigmas use back det low high Reading out pixel values from the display get curs Measuring position and FWHM of an object center gauss The default file type in MIDAS is the BDF format If you want to handle a raw or pipeline produced FITS image you have to append the extension fits to the filename The default command qualifier is ima So comp is equal to comp ima For further information please refer to the MIDAS help GUI in the quicklook window of OMEGA2000 02 12 2008 13 01 146 OMEGA2000 manual doc Appendix
148. ro sets the relative offset sum to zero ttele Tel shows the relative offset sum tele is a background process and should have a sync after it when used in a macro syntax tele focus 4 Move telescope focus units micron syntax tele pos ition Reads the telescope coordinates syntax tele time synchronizes telescope and computer time syntax tele get allpositions Requests tele pos and tele focus syntax tele nod main offset Moves the telescope to the desired nodding position UKIRT only syntax tele Print telescope name and TECS status telgui type USER syntax telgui x xserver f font Starts a graphical user interface GUI to the telescope X X terminal or X server to connect f font for menus and buttons tempcontrol type USER syntax tempc on x xserver f font Starts temperature controller Useful for Max only x where to open the window e g xt28 0 f font family e g lucida 121 02 12 2008 13 01 OMEGA2000 manual doc temphistory type USER syntax temph file x timel time2 f timel y templ temp2 d xserver see tempplot tempplot type USER syntax tempp file x timel time2 f time y templ temp2 d xserver Plots temperature log file created by tempcon X axis minutes Y axis degrees Kelvin x timel time2 begin end time
149. roduce flat images if the illumination would be homogenous Turning the argument around a flat field image is a homogenously illuminated frame which can be used to correct the measured signal by dividing the images by such a normalized flat field frame As every science frame is divided by this flatfield image care has to be taken not to reduce the S N of the science frames by underexposed flatfields One has to make sure that the S N of the flatfield images is much higher than that in the science frames including object signal in order to preserve their S N The effects just described are multiplicative effects i e they change the counts above back ground from the objects to be measured There are also however additive flat field effects which also produce non flat images but do not change the signal from the objects under study Scattered light within the optics and fringing due to night sky emission lines are the two most important examples for additive flat field effects In practice it is often difficult to disentangle additive and multiplicative flat field effects and the inability to do this often limits the photo metric accuracy achievable The optimum way to get at least a global multiplicative flatfield is to observe a star during photometric conditions placed on the detector at regular intervals e g every 30 in both X and Y As this procedure is certainly not practicable during regular observing runs we plan to provide such f
150. rom interstellar dust in the plane of the Galaxy In the plane of the Gal axy away from the Galactic Centre it can be approximated by a 17 K blackbody and e 10 3 9 02 12 2008 13 01 OMEGA2000 manual doc SEP South ecliptic pole emission as measured by the Cosmic Background Explorer COBE spacecraft CST Cryogenic space telescope cooled to 10 K with e 0 05 CBR Cosmic background radiation 2 73 K blackbody with e 1 0 The dominant source of sky background emission in the wavelength range concerned by OMEGA2000 is the OH emission often expressed in units of Rayleighs 1 Rayleigh unit 2 10 Az photons s m sr 1 5808x10 2 W m sr 1 Rayleigh A 0 1870423 phot m s nm n A detailed calibrated OH emission spectrum is published by Maihara 1993 Ramsay 1992 a high resolution spectrum by Rousselot 2000 For a complete overview of the nightsky background see Leinert 1998 In narrow band imaging the level of the night sky does depend critically on the exact pass band Therefore no empirical values for OMEGA2000 can be given yet For the broad band filters the following table gives the approximate levels to be expected to be updated J 80 R A H 260 R A K 430 R A Table 1 Background levels in the most common observing bands 02 12 2008 13 01 10 OMEGA2000 manual doc Detecting photons 3 1 Focal plane arrays for the infra red Infrared focal plane arrays FPA differ
151. sec ond readout the efficiency of this readout scheme is 5096 for the minimal integration time The CDS with fast reset is planned to be one of the optional readout modes for scientific op eration Reset Read Reset Read Integration Read 1 line 1 line 1024 line 1024 line 1 line 1024 line Figure 21 The scheme of correlated double sampling with fast reset reset read read row time Figure 22 Alternate representation of the double correlated read with fast reset Line interlaced Read It is possible to extend the CDS with fast reset in such a way that the readout of the integrated signal in each line is followed by a line reset and a readout of the reset values in that line As a result a complete frame is reset and its reset level is read out for the next cycle while the ar ray is clocked line by line to obtain the integrated signal in the actual cycle This method of interlacing the neighbouring readout cycles of lines is the most effective solution for CDS because each line is reset and the bias values are read immediately after reading the integrated pixel values Figure 23 The CDS with fast reset waits until the video signals in the whole 23 02 12 2008 13 01 OMEGA2000 manual doc array have been read before resetting the unit cells in the next cycle To obtain just a single image the CDS with fast reset takes the same time as the line interlaced mode but for a se quence of many repeats the latter is
152. sktop for the tasks indicated Once the desktop is activated the corresponding tasks are started by clicking on the panel to the right with the OMEGA symbol or the MPIA logo respectively These but tons as do all the others hide pop up menus which can be opened by clicking on the small triangle above the symbol to show the following OMEGA specific tasks missed terminal me cosariirig A Tristan lor l Waso E ainia E ia RIPENE HL Mandal EAIN AA ooo Figure 33 The available screens to operate OMEGA2000 Clicking on a task opens an X terminal and starts the specific task e g the MIDAS session for the pipeline If you click onto the OMEGA2000 or the MPIA symbol without opening the pop up menu you directly start the OMEGA2000 GUI and the observing window respec tively Please note that in case of MIDAS sessions the X terminal will automatically be closed if you terminate the session 02 12 2008 13 01 30 OMEGA2000 manual doc The following setup proved to be useful Left hand screen GEIRS GUI and MIDAS session for pipeline reduction Right hand screen General DATspooler MIDAS sessions for Quicklook and Observing The MIDAS sessions start automatically after pressing the pull up buttons You have how ever to set the path in each session ch dir to where the data are save path set in GUI Currently it is best to start the desktops in the following sequence in order to not loose colours in those windows
153. sky was taken 20 north of the galaxy For extended objects the sky mode should be set to minimum This ensures that the back ground is taken mainly from the sky exposures and will not be influenced too much by the extended object The angular distance of each exposure relative to the first one in the cata logue is limited to typical dither offsets So the sky exposures are ignored in the summed im age 02 12 2008 13 01 88 OMEGA2000 manual doc Appendix 1 Filters Broad band filters Filter cut on 5 cut on 50 cut off 50 cut off 5 comment block z 083 098 0 99 SDSS ISSAC 0 97 0 996 1 069 1 099 MANOS 1 09 1 10 1 345 1 355 Tiow 1 146 1 156 1 250 1 259 MANOS Jhigh 1 243 1 254 1 359 1 369 MANOS Js 1 15 1 165 1 325 1 335 NIRIJ 1 485 1 51 1 785 1 810 MASS 1 86 1 94 2 28 2 34 E Ks 200 230 233 2MASS 1 97 2 00 2 40 2 42 Methane off 1 52 1 53 1 62 1 63 T dwarfs Methane on 1 63 1 64 1 75 1 76 T dwarfs Table 3 Broad band filters Filter cenital comments block wave He I 1 083 Pa y 1 094 NN Jsmall 1 187 not available Narrow band filters 1 continuum 1 207 x Important OI 1 237 Due to the extended detector sensi Fe II 1 257 tivity beyond 2 6u several filters pap 122 need to be blocked in the long wa rap ies velength part by an additional blo Fell 1 644 po 1 O cking filter These are marked by an continuum 1 710 asterisk in th
154. so display the current telescope position after each offset Relative offsets Offsets in arcseconds can be supplied in the dx and dy windows Clicking on one of the directional buttons in the compass panel will then offset the telescope by the re quested amount The set zero button zeroes the cumulative offsets S dx and S dy and the 0 0 button in the centre of the compass returns the telescope to this defined zero posi tion Object Files n object file can be given in the Object List window the obj extension is not necessary Objects can be selected with a single click and set with the set button Setting an object sends the object s coordinates to the RA and Dec windows These can then be sent to the telescope computer by clicking on move as described above A useful feature is that when an object is set the airmass panel will display the object s current airmass in graphical form though there is no obligation to actually move to the object See also Section 9 7 on page 44 for a description of the format of such an object catalogue 9 3 4 SAO Map Window The SAO map shows an area of sky centred on where the telescope is pointing The display includes all of the SAO stars in the vicinity colour coded as to spectral type Blue O B Green A F Yellow G Red K M Black unclassified where the size of the dot indicates relative brightness The dashed red square shows the size of the camera field of view A scale bar in the upper left c
155. ssels are only filled half to allow a maximum tilt angle of the telescope of 90 e g for balancing of the telescope and nitrogen filling in the prime service position see image on cover With both vessels filled up to half of their capacity and all cooled parts in thermal equilibrium the dewar retains a temperature of 77 K for about 34 hours Dewar cool down 300 Filter Box Motor Detector Plate Cold Plate 200 Outer Shield 250 150 Temperature K 100 50 0 2 4 6 8 10 12 14 16 18 20 22 0 delta time h Figure 31 Monitoring the dewar temperatures during cool down 02 12 2008 13 01 28 OMEGA2000 manual doc The 3 5m telescope Although the telescope system is pretty much independent from the instrument control there are some parameters that must be set correctly within the telescope software in order for OMEGA2000 to work properly Coordinate system The 3 5m telescope knows three different software coordinate systems e AD is the Right Ascension Declination Here an offset in RA specifies the rotation of the hour axis in arcsec e XY is the detector system Offsets in X are the actual movement of the objects on the detector i e the cos 5 is taken into account AX Aa 15 cos Please note that you will not come back to the origin if you move the telescope e g in a rectangle of equal sides due to the field rotation described in Section
156. sss 22 Figure 18 The scheme of non correlated sampling reset read ememmemwo 22 Figure 19 The scheme of correlated double sampling reset read read 23 Figure 20 Alternate representation of the double correlated read e 23 Figure 21 The scheme of correlated double sampling with fast reset reset read read 23 Figure 22 Alternate representation of the double correlated read with fast reset 23 Figure 23 The scheme of the line interlaced read eroi ed rat A ST bid Ned me an diu 24 Figure 24 Alternate representation of the line interlaced read sss 24 Figure 25 The scheme of the multiple end point read sees 24 Figure 26 Centre to corner image distortion of the OMEGA2000 optics sss 25 Figure 27 Working principle of the movable warm baffle With only a cold baffle top rays from outside the primary reach the detector These may be blocked by the movable Dates A AAA 26 Figure 28 The two warm baffles s er Cete tiet AN oie 26 Figure 29 Movable baffle measurement Histogram of the SNR ratios with and without the movable baffle Left panel K filter Right panel K filter lt lt lt e 27 Figure 30 Block diagram of the read out electronics seen 27 Figure 31 Monitoring the dewar temp
157. stance between these two objects calculated from the X and Y coordinates on the detector using a constant pixel scale 15 02 12 2008 13 01 OMEGA2000 manual doc enable extraction of the pure source signal But the situation is different as we automatically get neighbouring sky for free in our images Only in case of very extended objects filling a good fraction of the FOV do we still need to take separate sky expo sures The technique to determine the sky from the science frames themselves is called dithering Between science exposures of the same field the telescope is offset by small amounts bringing the objects to slightly different places on the detector This allows a 1424344 442 given pixel to see pure sky in most of the images In the example at right pixel A sees pure sky in frames 1 to 4 pixel B only in Figure 13 Determination of frames 1 and 2 Stacking images via a median like process elimi sky background from dithered o i science frames nates object signals and cosmic ray events The result is a frame with pure sky only There are two caveats however As men tioned above offsetting the telescope introduces a field rotation Thus in dithered images the images cannot be aligned perfectly The effect for low declination and small dithering offsets is small however Furthermore the sky illumination is changing both in level and in shape FaBbender 2003 Therefore a consistent sky image c
158. style If you change the directory the new filesystem will be checked If the capacity is below a certain value you will receive a warning from the system To check the currently usde directory use the command cd to get the directory and the free capacity If a basename was given for the default filename th new directory is searched for matching filenames which could result in a conflict by a larger digit value in the name If a possible conflict was found next fr larger value is taken as next default filename else the default filenam stays the same Without argument the directory is UNIX like set to the home directory of the user The directory save path and the freespace is always output cho type 02 12 er USER 2008 13 01 102 OMEGA2000 manual doc this command is available at UKIRT only syntax chopper beam A B Set chopper to position A or B swithes to DC mode The communication is done through IRL electronics syntax chopper throw arcsec Defines chopper throw peak peak in arcsec on the sky This command just changes the FITS header no communication to the telescope syntax chopper angle degrees Defines the chopping angle This command just changes the FITS header no communication to the telescope syntax chopper mode rectangle sawtooth dc Defines the chopper mode This command just changes the FITS header no co
159. ta set itime tot pointing tot single single tot single sky Integration times in seconds tot pointing is the total integration time for the pointing This parameter determines the final limiting magnitude of the pointing Tot pointing tot single images are take at different dither positions tot single is the time for one integrated image which is equivalent to the integration time at a one dither position Tot single single exposures are added up in memory be fore the final single image with an integration time of tot single seconds is saved on disk single is the a single exposure integration time This parameter is to be optimized for each filter to allow background limited observations while being within the linear de tector regime tot single sky is the total integration time for a single integrated sky exposure If this parameter is omitted the object integration times will also be used for the sky The to tal integration time for sky observations is the fraction tot single sky tot single of the total object observation time Note To prevent truncation errors when calculating the number of repetitions tot pointing should be a multiple of tot single and tot single should be a multiple of single The single exposure time single is also used for the sky observations thus tot single sky should also be a multiple of single move Distance of sky field from object in arcminutes direction Direction from object for the desi
160. tars from M2000 138 Figure 63 Astrometry field at RA 18h finding chart for astrometric stars from M2000 139 Figure 64 Astrometry field at RA 22h finding chart for astrometric stars from M2000 140 Figure 65 Elevation plots for the astrometry fields January and April 141 Figure 66 Elevation plots for the astrometry fields July and October 142 Figure 67 Dual screen X terminal to the right operates the camera The screen at left is for telescope operation ue de eR Cet dd orna tease diodes Ai 145 List of Tables Table 1 Background levels in the most common observing bands uses 10 Table 2 Image rotation as a function of declination essere 15 Table Broad Dando Bless ossi etna Fatum eom en oe umen Co aes 89 Table 4 Narrow band filters Les vetu hu Rib prO sou ease ainsi demus 89 Table 5 Exposure times for dome flats visita 9 Table 6 Exposure times for twilight flats sess 92 Table 7 Photometric zero points counts for zero magnitude sess 143 02 12 2008 13 01 6 OMEGA2000 manual doc Introduction Observations at infra red wavelengths in the range between 1 and 2 5p are in principle very similar to CCD observations in the optical wavelength range Differences occur primarily due to the high background level in the IR thermal background and night sky and the different
161. the SW mode SINGLE MAIN INTERFACE stripchart type USER syntax stripc x xserver Opens the strip chart window x where to open the windwp e g xt28 0 subwin type USER syntax subwin HW SW auto wid xlstart ylstart xsize ysize subwin on off HW SW auto wid subwin clear HW SW auto subwin HW SW DET currently only implemented for instruments with MPIA ROE2 Enables disables clears and sets the hardware HW and or software SW subwindowing Instead of HW SW there is also the auto option where the SW will assume that the given windows has to be acquired via optimal HW windowing So the software will automatically convert auto given windows to SW and HW windows subwin on auto will clear all HW windows and redefine the needed HW windows for the instrument via current SW windows list If the instrument has no HW windowing available enabled always fullframe readout with SW windowing is executed Subwindows are only added if the list of subwindows is not yet full and wid number is not yet used for a subwindow where wid of SW windows are overwriting any wid of HW window 02 12 2008 13 01 118 OMEGA2000 manual doc definition But for HW windowing only the wid of the HW window definition is used Currently max subwindows count is at least 2 times number of data output channels of the detector NQ But for ROE2 the
162. the calibration files o2k pipeline icat obs B frames 2 mode 0 2 sum 2 Do only single image reduction of the image catalogue obs B cat Use the minimum mode with averaging of the 2 smallest values and sky determina tion from 5 frames 2 on either side The calibration frames are read in from the default calibration file according to the filter used o2k pipeline icat automatic frames 2 mode 1 sum 9 0 2 kappa sum 8 flatfield norm flat fits bpm std fits disk a o2k dark frame fits Use the current image catalogue of the ongoing observations The sky is de termined from 2 2 1 5 frames in the fast median mode The reference im age for the summation is computed every 9 images single image reduction and summation is done and the final cosmics cleaned sum image as well as the real uncorrected sum image and the difference image are saved The cosmics clipping parameter is set to 8 sigma above the median The flatfield norm flat fits and the bad pixel mask bpm_std fits are in the local direc tory the dark current frame is stored in disk a o2k dark frame fits o2k pipeline help Shows help text Parameters external command line parameters Pl P2 77 image catalogue Name and path if not local of image catalogue containing all images to be reduced If icat automatic the online reduction is activated i e the image catalogue created by the currently running observing macro is used and the data is redu
163. the time being also idle break should not be used as it results in images which are not properly flatfieldable The current default is thus idle wait In this situation the overhead can become substantial and it is thus mandatory to optimize the settings of integration times and number of co adds In general one should aim at low integration times and large number of co adds This minimizes the overhead due to the idle wait setting Integration times have however a lower bound as the images should be limited by background and not by de tector read noise Example If one takes images with 100sec integration time e g for narrow band imaging the following overhead without telescope movements have to be expected co add 1 elapse time is more than 200 sec due to idle wait dummy read and actual in tegration i e the efficiency is lt 50 co add 5 elapse time is somewhat larger than 600 sec so now the efficiency is 80 A practical example which includes also the telescope movements is a typical observing se quence for the HIROCS survey where we use command o2k dither with 25 dither posi tions The individual exposure time is 3sec 20 of which are added up in memory nco add 20 A complete sequence gives thus 1500 seconds of integration and it takes 38 min utes to complete Thus the efficiency is 66 02 12 2008 13 01 48 OMEGA2000 manual doc 13 Observing utilities General Remarks The utilities described in this chapte
164. to specify the integration time The flatfield frame has to be normalized to 1 internal in PRG OMEGA_pipeline prg contains a few internal parameters that are used as defaults and the online mode The corresponding keywords are specified in Section PIPELINE SETUP file_path Has to contain the same path information as the file_path keyword in the observing macros The keyword is needed for the online mode to allow communication to the current observing macros cal_file Keyword containing the path and name of the default ASCII calibration file 79 02 12 2008 13 01 Calibration File In P8 calibration frames the name of an ASCH calibration file can be specified see above The calibration file has to fulfil the following format conventions OMEGA2000 manual doc calibration cal OR Rene Fassbender IRONMENT MIDAS Calibration file S IR pipeline list name and path of calibration MPIA Heidelberg files to be used ORD OSE ENT S CONVENTIONS lines starting with T Lines with calibration frame information identifier BPM for the bad pixel mask and FLAT or the filter nam If FLAT is present FLAT has priority over FILT NOTE The filter names hav the descriptor FILTER identifier is followed by h information DARK for the ER to b The pat and Specification of flatfields If the iden are comments
165. tree waterline 61 13 6 Taking dithered science frames A aa OA bir E A AE 63 13 6 1 Survey observations a dt me i no s vase 63 13 6 2 Extended objects 1a dude pav t tu ati Dedi tae at D OI S t M esu ndi 68 13 7 MEANS the SeeIDE A e ded nae ed ey deu a 72 13 8 Pixel accurate alignment of the telescope enero tr emi ER ite a ina 72 13 9 Relative calibration of survey fields si ie ae id 73 13 10 Determining bad pixel mask and dark frame see 73 13 11 Monitoring atmospheric transSMmisSiON lt lt w wwwmmemmenimmmnnm win amwim mama 74 13 12 List FITS files 0n disk ai ica 74 13 13 Eist PI SAAC S ONE coe bre rtf bae cn Chet te teda disc ens 74 14 Online data reduction pipeline osos cette E Er vett en Estee bc do ento ed 76 14 1 Pe Onine Mode uis eet evens fede noel KE MANA pig etude AKATA Gh 81 14 2 Plowoharts for PID DA 84 JADI OV CLIC ET 84 14 22 Sky Determination ls 85 14 2 3 Summation of dithered IMSS ito 86 14 3 Examples of pipeline results oe A n A appo eir t ee dal 87 14 3 1 Images taken with O OE i eerte rere e casa esce eri ree 87 14 3 2 Images taken with 02k sky olt eere oet eene utis eeu sed wiza 88 Apple HP 89 Appendix 2 Flat field exposure times d ret eh a 9 Appendix 3 Detector Propecia 93 Appendix d DAT SO ea e str sence ete abel assu at ce ud 95 Appendix 5 FITS keywords written by OMEGA2000 esses 98 Appendix 6 Complete list of macros aste rere
166. trument programm Usually the instrumentation software calls the via systemcall Cal QueueFiles path filename Using the spooler from an xterm Create a list of FITS files to be saved into a file newdata sav e g with 1s path fits gt newdata sav path to directory where FITS files are stored Launch the spooler with QueueFiles newdata sav During the tape copy process further files may be entered into the queue Checking the tape content Using the command FitsList one may check the content of a tape The user has to create a file named KEYS LIST with the help of which the spooler knows which fits keywords to list 95 02 12 2008 13 01 OMEGA2000 manual doc Besides that the program also lists the number of records in each file and ist size in bytes SDATSPOOLER config KEYS LIST is used if the user does not supply a keyword file FitsList device nfiles firstfile device name of the tape drive e g dev rmt 0cn nfiles number of files to list firstfile first file on tape with which to start listing spooler control QueueControl reset Deletes all entries in the queue QueueControl list Lists all files in the queue QueueControl restart Restart the spooler If there are files in the queues not yet copied to tape these will be now copied QueueControl Stop Interrupt copying to tape Resume with restart Environments DATSPOOLER_DIR datspooler cshre It is necessary to call this file once
167. um 1 710 E a continua 2260 c 255 1 Table 5 Exposure times for dome flats 9 02 12 2008 13 01 OMEGA2000 manual doc Twilight flats It is assumed that the telescope is pointing a direction away from the sun and that the sky is clear no clouds Filter Acentre u phos a At sec remark z NEN EN Y L1 o d d KA s mes ka wama 00 continuan 137 por 127 p Fem 1257 eB 122 rem 1644 I continuum 1710 3 wximun 220 1 225 Table 6 Exposure times for twilight flats 02 12 2008 13 01 92 OMEGA2000 manual doc Appendix 3 Detector properties Read out modi e o2dcr double correlated read e fer double correlated read with fast reset e lir line interlaced mode recommended mode Make sure the idle mode is set to wait Check with idle in the camera window red back ground In this mode the detector is linear to better than 1 up to 25 000 cts The observing utilities assume a linearity up to 20000cts to be on the safe side deviation from linearity cts 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 level cts The detector should be operated in 32 channel mode default to be selected during start up Please note that the read out electronics has to be reset with power off
168. ve to use after the frame has been closed in step 3 If the data frame were opened and used by another application between step 1 and 3 serious software trouble would occur Most likely the pipeline and the other MIDAS session trying to open the unclosed frame would crash Thus a few precautions should be met to be on the save and prevent a session crash e The screen output contains the information on what frames have been closed These images are save to access with other applications e The intermediate summation results are saved on disk after every n th frame Before a new output frame is created the old one is closed Thus the summation frame with the currently highest index ndex sum icat fits is critical and should not be opened However the summation frame with an index 1 lower than the highest can be accessed and opened by other applications without any problems Predefined Modes The following examples state recommended parameter sets for different pipeline applications a Online reduction for normal observations o2k online without any parameters Uses fast median mode with a total if 5 frames for the sky determina tion The intermediate summation result is written to disk every 7 frame 02 12 2008 13 01 82 OMEGA2000 manual doc b Online reduction for observations of extended objects o2k pipeline icat automatic frames 2 mode 0 1 sum 7 0 0 Uses the fast true minimum method for the sky determination with a total of
169. x quit Leaves the command shell and kills all subprocesses display gui telgui satcheck If encountered during executing a macro quit just terminates the macro read type USER syntax read c Read crep images according to the actual cycle type c continous read of crep images until abort read is a background process and should have a sync after it when used in a macro repeat type USER syntax repeat command arg Repeat for the number the command The command is always executed as foreground process inside repeat resets type ENG syntax resets Set the number of resets Max only rmode type ENG syntax rmode slow fast Set reset mode Max Omega new IRL electronics only Note fast reset mode is not implemented rottab type USER syntax rottab x display m Starts rotator table GUI X display name m mute mode do no talk to device for tests only 115 02 12 2008 13 01 rtime type syntaz ENG rtim OMEGA2000 manual doc 4 e Set cycl reset tim of clock tics at the beginning of each e line MPIA electronics only saad type syntax ENG saad Do s x y x yd hift amp add on images 2 through kn in a box of size d Find peak pixel around Over write image l with the result of the shift amp add procedure satcheck type syntax US sa ER CC Swit abso from abou LE synt
170. xt If called without a parameter aperture prints all possible aperture positions and the actual one The wheel and ext depends on the actual camera system aperture is a background process and should have a sync 02 12 2008 13 01 100 OMEGA2000 manual doc after it when used in a macro area type USER syntax area xl yl x2 y2 Sets the area of the image that is used for all save operations except d dump file xl yl lower left corner x2 y2 upper right corner area without parameters returns the actual save area autosave type USER syntax autosave yes on no off s f n 1 n r nl n2 1 d The switches are explained with the save command Without parameter the actual autosave status is printed Enables disables automatic save operation after during a read backup type USER syntax backup path device Copies all files in the directory path to device You must enter the full path beginning with You have to set the actual save path to a different directory than the one to be copied Default device is dev rmt 0n for max moritz and dev rmt ln for omega omega and magic omega example backup disk a user dev rmt 1n WARNING Use only if you know what you are doing This routine uses dd to copy files from disk to tape Nothing else If you are not sure what this means to your data use tar as bac
171. xt com mand in the following way 88 O2K UTIL obs macros calibration series Defaults ident no default use quotes if containing blanks time no default coadds 1 one image per read cycle number 5 take 5 read cycles spacing lin exposure times increase linearly save S save all images of a read cycle as single frames reset no reset historical option to avoid detector problems Use default unless you know what you are doing Examples e o2k calser dark 300 Takes 5 dark exposures with exposure times from minimum available time to a maxi mum of 300sec The exposure time increases linearly from exposure to exposure e o2k calser flat H 2 10 3 log Flatfield with 3 integrations added in memory Five images taken Logarithmically increasing exposure times between 2 and 10 sec e o2k calser help Shows help text Parameter explanation External command line parameters P1 identifier P2 gt P3 time or min time max time Longest exposure time in series sec starting with 0 or minimum and maximum integration time between which exposures will be taken P4 coadds 02 12 2008 13 01 50 OMEGA2000 manual doc number of exposures to be taken in a read cycle P5 number Number of images read cycles to be taken This defines the intervals in exposure time between minimum and maximum P6 spacing Exposure times may be increased linearly lin logarithmically log or not at all zero In the latter
172. yed OMEGA2000 manual doc detector primary mirror floor floor detector i y y mo M Figure 27 Working principle of the movable warm baffle With only a cold baffle top rays from outside the pri mary reach the detector These may be blocked by the movable baffle Figure 28 The two warm baffles no part of the warm dome is seen by the detector The theory behind this baffle is de scribed in detail by Bailer Jones Bizenberger et al 2000 The influence of the movable baffle was tested in a cold winter night It gave the predicted gain in signal to noise FaDbender 2003 Tests in a warm summer night remain to be done 02 12 2008 13 01 26 OMEGA2000 manual doc Frequency Frequency 7 NSSSSSSSNSNSNSSNSNSNSSSNSNNNNS QQ GG Y YY gc pe cp pp E ae ae e Dp p ap p a c 4 3 E TRA E E E T TNNT E SENE NIS NUT NI TNT INT SS O A LS RII TNT NEST DIES NT 0 9 0 95 1 1 05 1 1 1 15 1 1 05 1 1 1 15 1 2 Kp_SN_realratio Unitless K_SN_realratio Unitless Figure 29 Movable baffle measurement Histogram of the SNR ratios with and without the movable baffle Left panel K filter Right panel K filter 7 5 Read out electronics IR array Rockwell HgCdTe 2048x2048 HAWAII 2 power ICB DSP clock supply control Datalink Datalink parallel serial parallel serial r parallel O parallel 1 O Id sonal VO PCD 60 PCD 60 as

OMEGA2000 user`s manual - Calar Alto Astronomical Observatory

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