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1. ISDC OMC Analysis User Manual Issue 5 0 28 COR_biastime biastime integer Integration time in sec for bias derivation Possible values 0 100000 Default 630 COR_kscKappa kscKappa integer Number of standard deviations for KSC algorithm Possible values 1 10 default 3 8 2 o_gti The next part of the Scientific Analysis derives the Good Time Intervals GTIs for the current Science Window based on housekeeping data information about satellite stability and if given user defined time intervals The script o_gti calls the following executables to obtain the GTIs gti_create gti_attitude gti_import e gti merge The output data structures are described in Section C 2 8 2 1 gti_create This program generates all GTIs for one instrument that depend on the housekeeping and other parameters and are defined by comparison of the values with values given in a limit table It also writes the GTIs in the new GTI tables that are organized in an index group All GTIs that belong to the same group are merged to one GTI and are written to one GTI Data Structure In the course of OMC data analysis this program is called twice to create GTIs defined by the spacecraft and OMC housekeeping All parameters associated with this executable are hidden Table 5 The gti_create parameters included in the main script Name Name Type Description main script executable GTLomcLimitTable LimitTable string The DOL
2. RA_OBJ Source right ascension in degrees DEC_OBJ Source declination in degrees RA_FIN Derived right ascension in degrees DEC_FIN Derived declination in degrees RA_FIN_ERR Standard error for RA_FIN cos DEC_FIN DEC_FIN_ERR Standard error for DEC_FIN EXPOSURE Effective exposure time in seconds FLUX_1 Flux in electron s derived from 1x1 integration boxes ERFLUX_1 Error estimate for FLUX_1 FLUX_3 Flux in electron s derived from 3x3 integration boxes ERFLUX_3 Error estimate for FLUX_3 FLUX_5 Flux in electron s derived from 5x5 integration boxes ERFLUX_5 Error estimate for FLUX_5 SKYBACK Mean flux from sky background in electron pixel s SKYERROR Error estimate for SKYBACK MAG_V1 Computed V magnitude for the 1x1 pixel area ERRMAG_V1 Error estimate for V magnitude in 1x1 pixel area MAG_V3 Computed V magnitude for the 3x3 pixel area ERRMAG_V1 Error estimate for V magnitude in 3x3 pixel area MAG_V5 Computed V magnitude for the 5x5 pixel area ERRMAG_V1 Error estimate for V magnitude in 5x5 pixel area CATMAG_V Catalog V Johnson magnitude CATERR_V Catalog error estimate for V magnitude PROBLEMS Flag for various problems FLAG Generic flag CENTRING_X Derived X axis offset of the source from the box center CENTRING_Y Derived Y axis offset of the source from the box center X_TAR X coordinate of the lower left pixel of the target box Y_TAR Y coordinate of the lower left pixel of the target box RANK Unique rank number of the box for the
3. Description OBT START On board time of start of the GTI OBT_END On board time of end of the GTI C 3 o_src_analysis This script derives fluxes calculates magnitudes and produces images for the sources targeted by the OMC The results of the script are kept in the OMC SRCL RES see Table 26 and OMC INTG RES see Table 27 OMC SRCL RES is a binary table with each row corresponding to one target box several shots are combined within a given time interval in order to obtain significant results for weak sources Photometry shots SHOTTYPE 1 are co added in contiguous groups found in the SWG whereas science shots SHOTTYPE 2 are co added to an integration time in seconds specified by the timestep parameter Note that while in the photometric shots SHOTTYPE 1 the targets are only photometric bright sources TYPE_TAR 1 the target of the science shots SHOTTYPE 2 can be different faint photometric stars TYPE_TAR 1 stars for science analysis TYPE_TAR 2 and data from the detector shadowed are for dark current and bias calibration TYPE TAR 3 OMC INTG RES is a binary table where each row corresponds to one integration within a given Science Window Table 26 Content of OMC SRCL RES Data Structure INTG_NUM Counter of recorded integrations used for cross reference OMC_ID OMC catalog source identifier ISDC OMC Analysis User Manual Issue 5 0 44 TYPE_TAR Target type Photometric 1 Science 2
4. ERROFF_X ERROFF_Y NUMCSTAR NUMBOXES GAIN READOUT DATALEVL SIGWCS_X SIGWCS_Y OMC_ID TFIRST BARYTIME X_WINSIZ Y_WINSIZ o_src_collect Shot sequence number Shot ID Instrument data mode Shot type 1 photometry 2 science 1 undefined X coordinate of the image from left ROP Y coordinate of the image from left ROP Local OBT acquisition time On board time of data acquisition Raw integration time Integration time Centering offset in X direction Centering offset in Y direction Centering error in X direction Centering error in Y direction Number of stars used in the centring error determination Number of boxes belonging to this shot Gain setting flag 0 low 1 high Read out port flag 0 left 1 right Processing level of data used to build image l sigma X axis accuracy of WCS solution l sigma Y axis accuracy of WCS solution OMC catalogue source identifier Time of the first data element Barycentric time for the first data element X size of the box Y size of the box This executable combines source data including derived fluxes and magnitudes distributed over several Science Windows into a single table OMC STAN RES see Table 29 Table 29 Content of OMC STAN RES Data Structure REVOL SWID TFIRST BARYTIME TELAPSE EXPOSURE SHOTTYPE OMC_ID TYPE_TAR RA_OBJ DEC_OBJ FLUX_1 ERFLUX_1 FLUX_3 ERFLUX_3 Revolution number valid for time of data taking Science Window identifier from which this row wa
5. SCW Science Window Data one Press the Specify Additional Parameters button at the bottom of the web page Deselect the View All checkbox press twice on it at the top of the Query table Select sew id and put the value 0102 without the quotes to specify all Scws from Revolution 102 Select scw_type and put the value pointing without the quotes or simply po to get only pointings Press the Start Search button at the bottom of the web page At this point you should be at the Query Results page with all the Scws available for revolution 102 Sort the Scw_id column by clicking on the left arrow below the column Name You can then select the two Scws we are interested in i e 010200210010 and 01020022010 Press the Save SCW list for the creation of Observation Groups button at the bottom of that table and save the file with the name omc lst The file name omc lst will be used later as an argument for the og_create program see Section 7 3 In this file you should find the 2 lines scw 0102 010200210010 001 swg fits 1 scw 0102 010200220010 001 swg fits 1 You should then download the data pressing the Request data products for selected rows button In the Public Data Distribution Form provide your e mail address and press the Submit Request button You will be e mailed the required script to get your data and the instructions for the setti
6. arc min possible values 0 180 default 0 5 DOL of a bad time interval table GNRL INTL BTI default Input BTI names to be considered default DOL of the user GTI table there is none default Time format in which the user GTI is given possible values IJD UTC OBT default IJD Used accuracy for OBT to IJD conversion and vice versa possible values any inaccurate accurate a Parameters specific to IMA level ISDC OMC Analysis User Manual Issue 5 0 20 IMA _timestep IMA_minshottime IMA _maxshottime IMA _maxCentOff IMA_numSigma IMA_magboxsize IMA_skyStdDev IMA_triggerlmage IMA_sciencelmage IMA_minSNR IMA_noiseLowLeft IMA_noiseLowRight IMA_noiseHighLeft IMA_noiseHighRight IMA_minBoxFrac IMA_minTimeFrac IMA_usePrp integer integer integer integer integer integer real boolean boolean real real real real real real real boolean Approximate integration time of output exposures s The actual integration time depends on the times of individual shots and the available time per Science Window Exposure times within a Science Window are roughly balanced modifying the given value as required possible values 0 100000 default 630 Minimum allowed shot integration time Shots with shorter inte gration times will be skipped defa
7. omc_stan_res fits This file is a big table with the results obtained for all shots and boxes see Table 29 in the appendix for the description To select the results corresponding to the source of interest the easiest way is to use the program fcopy from the FTOOLS package and source OMC_ID as a selection string For this you should find your source in the OMC reference catalog You can use the browse interface at http sdc laeff esa es omc 5 It is possible to query using the SIMBAD source name or search around the source position Now one can select all the rows with the given OMC_ID into a file crab_id_res fits fcopy omc_stan_res fits 1 OMC_ID 1309000071 crab_id_res fits Otherwise one can select all the rows having RA_OBJ and DEC_OBJ columns values exactly equal to the Crab coordinates as they are given in the OMC catalog RA_OBJ 8 363291667000E 01 and DEC_OBJ 2 201444444000E 01 respectively fcopy omc_stan_res fits 1 RA_OBJ 8 363291667000E 01 amp amp DEC_OBJ 2 201444444000E 01 crab_coord_res fits This should give the same result as selecting the rows with the given OMC_ID Now you can plot the OMC lightcurve of the Crab with e g the plot tool of fv by selecting to plot the dependence of MAG_V on BARYTIME the result should resemble Figure 9 Note that BARYTIME the barycentric time of the first element of a given data set is in IJD and the length of the data set TELAPSE is in seconds so the conversio
8. startshot 11 endshot 17 The resulting images resemble that of Fig 10 If one is interested in the image of the small box around the Crab one can give an additional parameter omc_id 1309000071 to the o_ima_build tool As a result one should obtain an image like that of Fig 11 As already pointed out one can now check from the image of the box that the Crab is an extended source for OMC All parameters of o_ima_build are also available in the main script omc_science_analysis So you could also obtain the same image by setting the corresponding parameters in the script instead of running by hand o ima_butld ISDC OMC Analysis User Manual Issue 5 0 23 Figure 9 Crab lightcurve ISDC OMC Analysis User Manual Issue 5 0 24 Figure 10 Sky map of the ScW 010200210010 13 shot ISDC OMC Analysis User Manual Issue 5 0 25 Figure 11 Image of the Crab box 13 shot ISDC OMC Analysis User Manual Issue 5 0 26 8 Basic Data Reduction In the previous cookbook chapter the example of the OMC data scientific analysis along with a description of the result was given In the current chapter we explain the internal structure of the omc_science_analysis script and discuss the intermediate results The structure of the main script is illustrated in Fig 12 along with the input and output Data Structures In order to avoid having to enter the location of the many Instrument Charact
9. 0 vi Acronyms and Abbreviations AD ADC ADU CCD DOL FOV FWHM GRB GTI IBAS IC IJD ISDC OMC Analysis User Manual Issue 5 0 Architectural Design Analog to Digital Converter Analog Digital Unit Charge Coupled device Data Object Locator Field of View Full Width at Half Maximum Gamma Ray Burst Good Time Interval Integral Burst Alert System Instrument Characteristics Integral Julian Day ISOC ISDC LED TOO OBT OG OMC PSF ScW SWG TBW TM Integral Science Operations Centre Integral Science Data Center Light Emitting Diode Target of Opportunity On Board Time Observation Group Optical Monitoring Camera Point Spread Function Science Window Science Window Group To be written Telemetry vii Glossary of Terms e box A small CCD window extracted from the CCD image for transmission to the ground It is used instead of window or sub window when needed for clarity e CCD active area The CCD area exposed to light e CCD storage area The CCD active area has a duplicate array of detectors which is masked from light e frame transfer A technique to acquire images with a CCD The charge generated in the active area is transferred quasi instantaneously to the storage area This area is the one used for the read out process allowing simultaneous read out of one image while the active area is collecting light for the next one e shot Each individual OMC CCD integration for image generation e I
10. 1 central pixel 3 3x3 area 5 5x5 area default 3 IMA_photCal photCal DOL of photometric calibration curve take from IC default IMA_minSNR minSNR minimum acceptable signal to noise ratio default 1 0 ISDC OMC Analysis User Manual Issue 5 0 35 8 3 3 o_ima_build This executable extracts all OMC boxes contained in a Science Window Group For normal science data and default parameters a 1072 x 1028 image is built for each shot with the boxes located in their real position on the OMC CCD The executable can also build small images for given sources see omc_id parameter If the user chooses to use trigger data an image is also built for each shot but the size is that of the trigger window see triggersize parameter For some sources the standard analysis OSA is not able to give good results or simply can not process them This is the case for extended sources that can even generate a mosaic of OMC boxes sources with inaccurate coordinates this happens for most of the high energy targets or data obtained in trigger mode For all these cases the users should execute o_ima_build to create standard astronomical images usable by most of the astronomical reduction packages e g IRAF SEXtractor and visualisation tools e g ds9 ftools When possible we recommend that users create corrected images level COR for their own processing In this way they are sure to use the best ca
11. above and stored in the omc lst file Firstly create an Observation Group see the description of the executable og_create in the Toolbox section of the Introduction to the INTEGRAL Data Analysis 1 og_create idxSwg omc lst ogid crab baseDir instrument 0MC As a result the directory REP_BASE_PROD obs crab will be created It contains the files og omc fits and swg_idx_omc fits as well as the subdirectory scw necessary for the analysis You are now ready to start the analysis cd obs crab omc_science_analysis ogDOL og_omc fits 1 startLevel COR endLevel IMA2 IMA_timestep 600 IMA_magboxsize 5 This command launches the analysis of the data attached to the Observation Group ogDOL 0g omc fits 1 The analysis will pass all levels from Data Correction startLevel COR until Flux Reconstruction and Results Collection endLevel IMA2 In order to obtain significant results for weak sources we want to combine the data so that the exposure of the new set is close to the IMA_timestep value of 600 s The last parameter IMA_magboxsize 5 chooses the 5 x 5 pixel area from which the flux will be collected for determination of the magnitude Crab is an extended source for OMC This is why to determine the V magnitude integrated over the source we choose to collect the flux from the 5x5 box centered on the brightest pixel which is slightly larger than for a point source After this command the script launches the Graphica
12. number of the box TYPE_TAR Type of the target Science Photometric X_TAR X coordinate of the lower left pixel of the target box Y_TAR Y coordinate of the lower left pixel of the target box SIZE_TAR Dimension of square box max 11 pixels PIXELS Pixel values in ADU If the trigger mode occurs see Section 4 4 the raw data are written to the OMC TRIG RAW see Table 16 This data structure is a binary table with one row per shot as each trigger shot contains only a single box ISDC OMC Analysis User Manual Issue 5 0 40 Table 16 Content of OMC TRIG RAW Data Structure SSC PACK_TIME NUM_PACKS LOBT_ACQ RAW_INTT GAIN READOUT OFFSET X OFFSET_Y ERROFF_X ERROFF_Y NUMCSTAR X_TAR Y_TAR PIX_FIRST PIX_LAST PIXELS Source sequence count of the packets for one shot Time in the data field header of the packets for one shot Number of packets for this shot Local acquisition OBT of the shot Raw integration time of the shot Gain setting flag 0 low 1 high Read out port flag 0 left 1 right Centering offset in X direction Centering offset in Y direction Centering error in X direction in pixel Centering error in Y direction in pixel Number of stars used in the centering error determination X coordinate of the lower left pixel of the target box Y coordinate of the lower left pixel of the target box First pixel contained in the current packet Last pixel contained in the current packet Pixel values i
13. of the GTI limit table GTL scLimitTable default take from IC 8 2 2 gti_attitude A spacecraft GTI named ATTITUDE is defined for each period of time when the pointing stability is better than the accepted tolerance For slews this GTI is always set to be good All parameters associated with this executable are hidden Table 6 The gti_attitude parameters included in the main script Name Name Type Description main script executable GTI attTolerance AttStability real Defines the accepted attitude stability tolerance in units of arcmin A GTI is created if the stability is better than this tolerance default 0 5 ISDC OMC Analysis User Manual Issue 5 0 29 8 2 3 gti_import The gti_import reads user GTI table and converts it to a table in ISDC format The user GTI can be defined either in units of OBT IJD or UTC The output is always in OBT The user table can define either bad or good time intervals The output time intervals are always good ones Table 7 The gti_import parameters included in the Main script Name Name Type Description main script executable GTI_gtiUser InGti string DOL of the user GTI table there is no one default gt GTLTimeFormat TimeFormat string Time format in which the user GTI is given gt possible values IJD UTC OBT default IJD GTL Accuracy Accuracy string Accuracy used for OBT to IJD conversion and
14. on a tiny chip Each pixel responds to light falling on it by storing a tiny charge of electricity During the shot charges are stored in the CCD active area area exposed to light After the end of the shot this area is copied to the storage area masked from the light From this storage area the information is read by the read out port and transmitted to the Earth In the OMC case there are two read out ports left one and right one Only one of them is in the active use and the second one is planned to be used only in case of problems with the first one In Figure 3 you will see the OMC coordinates definitions for the left and right read out ports and their orientation in comparison with the axes of other instruments The Analog to Digital converters ADCs that are used for OMC have the capability of digitizing the analog signal coming from the CCD read out ports to 12 bits i e they provide a discrete output in up to 4096 digital levels These convertors have been designed to be operated with 2 gain values At low gain the full dynamic range of the CCD 0 120000 cts per pixel maximum value is defined by the CCD full well capacity is digitized into 0 4095 digital levels ADU at a linear scale of 30 cts ADU At high gain only the 0 20000 cts per pixel range is digitized into 0 4095 ADU with 5 cts ADU This allows a more accurate photometry down to approximately the noise limit of the CCD Finally CCD is cooled b
15. results only for point like sources 2 For extended sources or high energy source counterparts with large uncertainties in their position the OMC planning assigns multiple adjacent sub windows to cover the whole area In that case multiple boxes are found with different ranks but with the same OMC_ID These adjacent sub windows will not be analyzed correctly as the software treats each box individually The photometric extraction has to be done manually in these cases once the accurate coordinates of the target are known To help the user these cases are flagged in the table of results 3 If the source coordinates are inaccurate by more than 2 OMC pixels 35 the software analysis will not be able to re centre the target and the derived fluxes and magnitudes will not be correct 4 If another star is within a few pixels of the source of interest it can introduce systematic errors in the derived fluxes and magnitudes The strength of this effect can be different for different pointings since the relative position in the sub windows will slightly change for different rotation angles 5 Since OSA 4 0 the detection of saturated sources has been improved significantly However some of the bright sources slightly saturating one or few pixels might not be detected as saturated sources As a consequence their derived magnitudes are not correctly computed The observer should check whether the source might be saturating the CCD for a given in
16. vice versa possible values any inaccurate accurate default any 8 2 4 gti merge This program merges zero one or more GTIs to a new GTI It is an AND operation a time in the result GTI is defined to be good if this time is in every input GTI defined as good Table 8 The gti merge parameters included in the Main script Name Name Type Description main script executable GTI_gtiScNames SC_Names string Names of spacecraft GTIs to be merged empty use default default GTI gtiOmcNames OMC_Names string Names of OMC GTIs to be merged empty use default default GTIBTI_Dol BTI_Dol string The DOL ofa bad time table GNRL INTL BTI De fault GTI_BTLNames BTI_Names string The BTI names of all bad time intervals that should be merged The names must be separated by one or more blanks or tabs Ifa BTI name does not exists in the BTI table it is assumed to be good all the time Default 8 3 o_src_analysis Extraction of the scientific results from data as well as creation of images is done by the script o_src_analysis This script derives fluxes and calculates magnitudes for the sources targeted by OMC calling the following executables e o_src_get_fluxes e 0_src_compute_mag ISDC OMC Analysis User Manual Issue 5 0 30 e o_ima_build optionally If the script parameter IMA_triggerImage is set to yes default value
17. 00 0002 2 eee ee eee 6 4 Background evaluation graphics os o cou uu aaam waa padda a Eee eee ee 10 5 Limam bright magnitude za is wi e ae aaa i a RR Re SS A 10 6 OMC Point Spresd Paneer e Ae eee oak R eS a aa A e 12 7 Overview of the OMC science analysis o aaoo aaa a a a 14 8 GUL tor OMC snalysiss les A AS A aa ww Be G 23 9 CPER NEDO VE y ea A AA AA a ee a ea we a 24 10 Sky map of the SoW 010200210010 18 shots e o oo ae 2k ni owe ee dee ees a 25 1i Tmageol the Crab bog 19 Shh cs ke A YE DD KY 26 12 Structure of the ome science analysis Seript o ooro aaa ee eR ER eo 28 13 Illustration of the geometry defining the background and source magnitude calculation 32 ISDC OMC Analysis User Manual Issue 5 0 v List of Tables 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 OMC parameters and scientific performances e 3 Photometric accuracy for different background levels in units of magnitude 11 Parameters for the omc_science_analysis s sas o o 19 The o_cor_boxr_fluxes parameters included in the main script o a 28 The gti_create parameters included in the main script o 29 The gti_attitude parameters included in the main script o o 29 The gti_import parameters included in the Main sScript o e 00004 30 The gti_merge parameters included in the Main script o a 30 The o_src_ge
18. HOT COR OMC BOXS COR o_cor_box_fluxes GNRL SCWG GRP OMC SHOT RAW OMC BOXS RAW OMC SHOT PRP gti create OMC BOXS PRP gti_attitude on E e gti_import OMC GNRL GTI IDX j E OMC GNRL GTI gti_merge OMC GOOD LIM 1IDX OMC GOOD LIM OMC BDPX CAL IDX o_src_analysis OMC BDPX CAL OMC PHOT CAL IDX o_src_get_fluxes OMC SRCL RES OMC PHOT CAL o_sre_compute_mag OMC INTG RES OMC TRIG RAW o_ima build OMC SKY IMA IDX OMC TRIG PRP OMC SKY IMA GNRL OBSG GRP omc_obs_analysis GNRL SCWG GRP IDX GNRL SCWG GRP o_sre_collect OMC STAN RES OMC INTG RE OMC SRCL RE Figure 12 Structure of the omc_science_analysis script Parameters specific to this level are given in Table 4 The output data structures are described in Section Cl Table 4 The o_cor_box fluxes parameters included in the main script Name Name Type Description main script executable ee COR_flatField flatfield string DOL of flatfield image take from IC default gt COR_darkCurrent darkpar string DOL of dark current amp bias calibration table take from IC default COR _higain higain integer Multiplication factor for high gain default 5 COR_lowgain lowgain integer Multiplication factor for low gain default 30
19. LOUS _PSF OMC_PROBLEM_LOW_FLUX 1 MC_PROBLEM_BADPIXEL SKY O OMC_PROBLEM_BADPIXEL_RIM 5 OMC_PROBLEM_BADPIXEL_RIM_3 OMC_PROBLEM_BADPIXEL_RIM_1 OMC_PROBLEM SKY_ERROR OMC_PROBLEM_UNKNOWN_MAG OMC_PROBLEM _EXTND _SRC 8 3 2 o_src_compute_mag Maximum allowed shot integration time The rest of the shots will be skipped default 200 Minimum allowed shot integration time The rest of the shots will be skipped default 1 Use prepared data for quality checking default yes Minimum fraction of planned boxes actually observed possible values 0 1 default 0 99 Minimum fraction of planned time actually observed possible values 0 1 default 0 99 DOL of Bad Pixel Table take from IC default gt Read out noise in e for low GAIN left read out port ROP fault 45 Read out noise in e for low GAIN right ROP default 49 Read out noise in e for high GAIN left ROP default 33 Read out noise in e for high GAIN right ROP default 35 Maximum acceptable Standard Deviation on sky back ground default 10 0 in PROBLEMS column in the No problems The mag was extrapolated No centroid is available or is inaccurate Bad PSF A default value was used The PSF shape is anomalous Flux of central pixel too low Bad pixel found in sky bgnd Bad pixel found in 5x5 rim Bad pixel found in 3x3 rim Central pixel bad Sky error larger than accepted limit Magnitude could not be ca
20. N Gain setting flag 0 low 1 high READOUT Read out port flag 0 left 1 right Y_BIN Y binning setting The off line full field analysis calculates normalized flatfield data and keeps it at OMC FLAT CAL The normalized flatfield data are stored straightforwardly as an image with the information about the dimensionless flatfield values with mean value of order 1 0 and axes along the X and Y CCD axes The OMC BDPX CAL contains the look up table of bad OMC pixels see Table 21 Table 21 Content of OMC BDPX CAL Data Structure DETX X coordinate of bad pixel position DETY Y coordinate of bad pixel position BADFLAG Integer flag defining the nature of the bad pixel 1 cold pixels 2 hot pixels The results of the photometric calibration of the OMC are in the OMC PHOT CAL data structure Table 22 It is a binary table which contains the information about the measured flux in electron sec the corresponding photometric magnitude and the estimation of its error Table 22 Content of OMC PHOT CAL Data Structure LOGFLUX Measured flux in electron sec MAG_V Corresponding photometric magnitude ERRMAG_V Error estimate for V magnitude The parameter limits defining good time intervals for the OMC instrument are kept in the OMC GOOD LIM Table 23 Content of OMC GOOD LIM Data Structure PAR NAME Parameter name OBT_START Start of validity of the limit values OBT_END End of validity of the limit values MIN_VAL Minimum values allo
21. Reduction o oi raia a e a A EP Poy LER RR a a ee 8 1 OCO SCIENCE enn baka eae pee a A weed DERE E RE Heed eae wees ISDC OMC Analysis User Manual Issue 5 0 11 13 14 16 16 17 18 19 22 27 27 iii 8 2 O98 oo ee ERE ER ORR RE Re ae a eee le 29 8 2 1 MEE cuba pea EE ee A eee aa eee 29 8 2 2 Ce at COOL EE RARE MS SRO eed bE ELS 29 8 2 3 ISO A he a a AI A 30 8 2 4 MMT a et ee a A Ge Bare ee ae ae ae ee Y 30 8 3 e aa avarai OOS 24 Dade wes ewe Pag mee amp GES 30 8 3 1 DICES AAA E A amp 31 8 3 2 OSTOCOMDULCINGG lt lt ok ia aaa a A 34 8 3 3 a AA RA 36 8 4 PIES RUSS on O RA AA AAA AA amp a 38 8 4 1 CURVE ee a a RA A ae wo Re 38 Known Limitations crisis ee okt eee EEE SOE EE ee a oS 39 A Low Level Processing Data Products ee 40 A Rea Date cane ee ee RE a OP MRS SP ee we a ee EE 40 AZ Prepared Data ostia OY SHEE EE EEE DOG GG 41 Instrument Characteristics Data used in Science Analysis o 43 Science Data Products a 6a 4 baa SHR a eee Ee ee ERS 44 Gi OGOS caidas isa a a aos 44 C 2 PIG 2 9 04 BT AAA A A eS ee 44 C3 DECIS a ARA A aa a A AA a Boe G 44 C 3 1 OLEA cs dra a a 45 C 4 PTI asec a A AA ADA RARA EEE YS 46 ISDC OMC Analysis User Manual Issue 5 0 iv List of Figures 1 A3Dcut of the OMC Camera Unit e 5 2 Optical system layon e socu m Ree ok Re eH RR eee ww Be RE 6 3 Spacecraft amp Instrument Coordinate Systems
22. SA_IC package and the Reference Catalogue OSA_CAT package are part of the OSA software distribution They should be installed following the Installation Guide for the INTEGRAL Data Analysis System 4 ISDC OMC Analysis User Manual Issue 5 0 16 Then just create a file omc lst containing the 2 lines scw 0102 010200210010 001 swg fits 1 scw 0102 010200220010 001 swg fits 1 which is the list of Scws you want to analyze technically we call them DOLs Data Object Locators i e a specified extension in a given FITS file This file name omc 1st will be used later as an argument for the og create program see Section 7 3 Alternatively if you do not have any of the above data on your local system or if you do not have a local archive with the scw and the aux branch available follow the next section instructions to download data from the ISDC WWW site 7 1 1 Downloading Your Data To retrieve the required analysis data from the archive go to the following URL http isdc unige ch index cgi Data browse You will reach the W3Browse web page which will allow you to build a list of Science Windows Scws needed to create your observation group for OSA Type the name of the object Crab in the Object Name Or Coordinates field Click on the More Options button at the top or at the bottom of the web page Deselect the All checkbox at the top of the Catalog table and select the
23. SDC system the complete ground software system devoted to the processing of the INTEGRAL data and running at the ISDC It includes contributions from the ISDC and from the INTEGRAL instrument teams e Science Window ScW For the operations ISDC defines atomic bits of INTEGRAL operations as either a pointing or a slew and calls them ScWs A set of data produced during a ScW is a basic piece of INTEGRAL data in the ISDC system e Observation Any group of ScW used in the data analysis The observation defined from ISOC in relation with the proposal is only one example of possible SDC observations Other combinations of Science Windows e of observations are used for example for the Quick Look Analysis or for Off Line Scientific Analysis e Pointing Period during which the spacecraft axis pointing direction remains stable Because of the INTEGRAL dithering strategy the nominal pointing duration is of the order of 20 minutes e Slew Period during which the spacecraft is manoeuvred from one stable position to another i e from one pointing to another ISDC OMC Analysis User Manual Issue 5 0 viii 1 Introduction The OMC Analysis User Manual i e this document was edited to help you with the OMC specific part of the INTEGRAL Data Anaysis A more general overview on the INTEGRAL Data Analysis can be found in the Introduction to the INTE GRAL Data Analysis 1 For the OMC analysis scientific validation report s
24. SY soc OMC Analysis User Manual AA SDO OSA UM OMO INTEGRAL Science Data Centre OMC ANALYSIS USER MANUAL Reference ISDC OSA UM OMC Issue 5 0 Date 23 May 2005 INTEGRAL Science Data Centre Chemin d cogia 16 CH 1290 Versoix Switzerland http isdc unige ch Authors and Approvals lt ISDC OMC Analysis User Manual Y 23 Way 200850 Y Prepared by M Chernyakova P Kretschmar Agreed by Re Walter raras dal A gee sine tas Oahu ees A da Approved by T COULVOISICH 24 cicoide darla t lil tales dh dora ah rod ISDC OMC Analysis User Manual Issue 5 0 i Document Status Sheet a ISDC OMC Analysis User Manual aNs 2 April 2003 E First Release 19 May 2003 Update of the First Release Section 9 Tables 3 9 11 and bibliography were updated 18 July 2003 i Second Release The bibliography was updated 8 December 2003 Third Release The Section 7 and the bibliography were updated 19 July 2004 l Fourth Release Table 3 Sections 8 9 and the bibliography were updated 6 December 2004 i Update of the Fourth Release Sections 6 7 9 8 Table 29 and the bibliography were up dated 23 May 2005 Fifth Release Cookbook and Basic Data Reduction sections 7 8 were updated Some small changes in the Instrument Definition part and bibliography Table 1 Table 6 changed into Table as 24 JON 2005 ISDC OMC Analysis User Manual Issue 5 0 ii Contents Acronyms and Abbre
25. TAR 1 the target of the science shots SHOTTYPE 2 can be different faint photometric stars TYPE_TAR 1 stars for science analysis TYPE TAR 2 and data from the detector shadow are for dark current and bias calibration TYPE TAR 3 In the flux calculation effects connected to the inconsistency with the planned data and the noise level are taken into account Bad pixels are determined in the course of calibration analysis and if possible are not used in the flux determination If after all bad pixels were used then the result would be flagged in the PROBLEMS column see Table 10 on PROBLEMS flags To compute the flux coming from the source the brightest pixel is searched in a radius of 0 2 pixels max CentOff parameter around the box center This brightest pixel is computed only once for each Science Window Group It must have a signal to noise ratio of at least IMA _numSigma if not no re centering is performed Taking the above re centering result as a starting point to compute the source centroid aperture photometry is performed after combining the data from different shots if it was required by the user according to IMA _timestep The main steps in this algorithm are e Estimate the background by using the 11x11 exterior pixel rim Rejection of high and low pixels is applied to avoid cosmic rays and noisy pixels e Use the faint photometric stars to compute the PSF width To this end an iterative method has been implemented to
26. added depends on the time during which the spacecraft keeps the same pointing without dithering typically 30 min The brightest stars saturate their corresponding pixels for such integration times but a combination of short and long exposures is performed so as to increase the magnitude range for a given field e A number of windows of typically 11x11 pixels or 3 x 3 are extracted around each object of interest and transmitted to the ground 4 2 Fast Monitoring Mode In the normal mode it is not possible to perform a continuous monitoring with a time resolution finer than 10 seconds Therefore when fast variability is expected the fast monitoring mode can be chosen With this mode integrations of 3 seconds are performed at intervals of 4 5 seconds and only the sections of the CCD containing the target of interest are read from the CCD and transmitted This of course implies that the position of the source is known with an accuracy better than the window size 11x11 pixels ie 3 x 3 and that the source is bright enough to be monitored with integration times below 10 s see Fig 5 below 4 3 The OMC Input Catalogue As explained above besides the proposed targets OMC observes astrometric and photometric stars and other targets of scientific interest within its field of view at a given time For this purpose a catalogue 5 has been compiled by the OMC team containing over 500 000 sources including e Known optical c
27. an one star per pixel with my between 17 and 19 The density of stars on the galactic plane indeed determines the limiting magnitude of the instrument At galactic latitudes b gt 30 the problem of source confusion becomes negligible except for specific cases in which bright stars are separated by just a few arcseconds 5 2 Limiting Faint Magnitude Assuming a minimum level of background and the combination of 10 exposures of 200 s each the limiting magnitude of OMC is found to be my 18 1 3 detection level This value corresponds to a limiting sensitivity of the instrument of 2 1x107 6 erg cm 2s A7 or alternately 5 8x107 ph cm7 s7 A71 at 550 nm At a maximum background level the limiting magnitude is my 17 5 Note that these sensitivities can only be achieved for isolated stars for which the background can be properly estimated Figure 4 shows the limiting magnitude for both maximum and minimum background as a function of integration time assuming in all cases that 10 images have been combined to increase the signal to noise ratio 5 3 Limiting Bright Magnitude The full well capacity of the CCD constrains the magnitude of the brightest stars that can be measured without pixel saturation for a given integration time With 10 s integrations the central pixel becomes saturated for objects brighter than my 7 With integrations of 200 s even stars with my 10 start to saturate the CCD Severe saturation of the CCD might imply losin
28. at good photometry can be performed in the V band for objects of quite different brightness Note that these accuracies can only be obtained for isolated stars ISDC OMC Analysis User Manual Issue 5 0 9 Stars per pixel Figure 4 Gal latitude j aa 10 30 90 15 16 17 18 V mag V mag 12 13 14 15 17 18 hb No Minimum background Maximum background 1 00 10 xt s N or Left Average number of stars per pixel brighter than a given V magnitude at different galactic latitudes Right Limit magnitude detection at 30 significance in V in best galactic pole no zodiacal light and worst galactic plane with zodiacal light conditions as a function of integration time assuming stacking of only 10 individual images Log counts pix A TITT I Im Ed T PTA T ENT I TITT T J A T TS i I TITT Minimum backgror Maximum backgro Saturation Max background Min background Figure 5 5 10 15 V mag Saturation time s 200 175 150 N n 100 75 50 25 V mag Left Number of counts on the central brightest pixel as a function of stellar magnitude The levels corresponding to minimum and maximum backgrounds have been indicated as well as the countrate at which the CCD pixels saturate The curv
29. current pointing PSF_FWHM Effective PSF FWHM in pixels Table 27 Content of OMC INTG RES Data Structure INTG_NUM Counter of recorded integrations used for cross reference OBTFIRST On board time of the first data element OBTLAST On board time of the last data element Time of the first data element IJD Time of the last data element IJD Total elapsed time of the data Shots type 1 photometry 2 science Shot identification of first shot Shot sequence number of first shot Shot identification of last shot Shot sequence number of last shot Position of first source of this integration in OMC SRCL RES Number of sources belonging to this integration TFIRST TLAST TELAPSE SHOTTYPE SHOTFRST SEQFRST SHOTLAST SEQLAST FIRSTSRC NUMSRCES C 3 1 0_ima_build This executable extracts all OMC boxes contained in a Science Window Group For normal science data a 1072 x 1028 image is built data structure OMC SKY IMA for each shot with the boxes located in their real position on the OMC CCD If the user chooses to use trigger data an image is also built for each ISDC OMC Analysis User Manual Issue 5 0 45 shot but the size is that of the trigger window The index file is written to the OMC SKY IMA IDX data structure see Table 28 C 4 Table 28 Content of OMC SKY IMA IDX Data Structure SHOT_SEQ SHOTID DATAMODE SHOTTYPE X_WINORG Y_WINORG LOBT_ACQ OBT_ACQ RAW_INTT INT_TIME OFFSET_X OFFSET_Y
30. d from the OMC Input Catalogue Two observation modes are available to the observer the normal and the fast monitoring modes 4 1 Normal Science Operations Mode In the normal science operations mode OMC monitors the optical flux of a number of targets including the high energy sources within its FOV other sources of interest stars for photometric calibration and masked pixels from the CCD to monitor the dark current Variable integration times during a pointing allow monitoring of both bright and faint sources Operations are performed automatically in the following way e The sequence starts by obtaining a series of images of 10 astrometric reference stars spread over the field of view This makes it possible to measure the pointing of the OMC optical axis with an accuracy of around 0 3 pixels 6 e Then a set of photometric stars is observed 10 stars in the field of view with good photometric quality e The CCD centered in a target field is then exposed with the following sequence of integration times 10 s 50 s 200 s After each exposure the full frame is transferred to the occulted part of the chip and the next integration starts An optimum use of the CCD from the point of view of the noise read out and cosmic rays is obtained for integration times of around 200 s so that for the faintest objects several exposures of 200 s are summed up during the analysis on the ground The number of integrations that can be
31. denote if box is normal saturated or blank 0 1 1 POS_OFF Flag if box position is inconsistent with planning SIZE_BAD Flag if box size is inconsistent with planning TYPE_BAD Flag if box target type is inconsistent with planning ISDC OMC Analysis User Manual Issue 5 0 41 RANK_BAD Flag if no planning data can be found for this rank number FAINTPHO Flag to mark faint photometric sources in science data OMC_ID OMC catalogue source identifier RA_OBJ Source right ascension in degrees DEC_OBJ Source declination in degrees EXTENSION Source extension MAG_V Source visual Johnson s magnitude SIGMA_V Source variability The prepared raw data for the trigger mode are kept in the OMC TRIG PRP see Table 19 Table 19 Content of OMC TRIG PRP Data Structure OBT_ACQ Full on board time of the shots INT_TIME Effective integration time of the shots ISDC OMC Analysis User Manual Issue 5 0 42 B Instrument Characteristics Data used in Science Analysis About once every two months dark current calibration and flat field calibration modes are foreseen The off line dark current analysis derives the dark current slope offset and bias values keeping it at OMC DARK CAL see Table 20 Table 20 Content of OMC DARK CAL Data Structure OB_TIME On board acquisition time INT_TIME Integration time of dark current shot DARK_CURRENT Mean dark current in electrons pixel VARIANCE Variance of dark current GAI
32. e bias value to be subtracted the Dark Current boxes within the data itself are used Subtracting the Dark Current from the Dark Current boxes leaves a remainder of Bias only From a user defined biastime a number of Bias array bins within which to determine Bias Values are determined From biastime end_times are also determined markers for comparison against shot_end_times for all shots to an end_time use the Bias level determined from the associated bin In determining the Bias Level the mean of all Dark Current pixels with Dark Current removed within a bin undetermined using the Kappa Sigma Clipping algorithm The number of standard deviations to use as the cutoff kscKappa is user defined Should data not be available to determine a bias value the most recently determined bias value is used and failing that a previously determined bias value is used The corrected output is then ready for photometric flux determination All parameters associated with this executable are hidden IC files and the multiplication factors for data conversion low and high gain see Section 3 3 for more details are provided by the OMC team Do not change the value of the parameters until you are really sure about what you are doing ISDC OMC Analysis User Manual Issue 5 0 27 omc_science_analysis OMC DARK CAL IDX omc_scw_analysis OMC DARK CAL OMC FLAT CAL IDX o_cor_science OMC FLAT CAL GNRL SCWG GRP OMC S
33. e has been computed assuming 10 s of integration time but the Y scale can be easily converted to any other integration values Right Integration time at which a star of given V magnitude saturates the central pixel ISDC OMC Analysis User Manual Issue 5 0 10 for which the background can be properly estimated Furthermore in case of dithering the photometric disperion is gt 0 015 mag in all cases This value 0 015 is the accuracy of the OMC flatfield matrix So if the source is observed in different detector pixels as occurs for a dithered observation the accuracy of the flatfield produces an additional scattering of observed magnitudes corresponding to 0 015 mag Table 2 Photometric accuracy for different background levels in units of magnitude oem 3 0 2 7 effective exposures assuming typical background level Ds EA 300s oos o 900 s 5 5 Focusing The focusing capabilities of the OMC system depend very slightly on the lense temperature and the pixel location over the detector The PSF Point Spread Function follows a Gaussian distribution whose FWHM Full Width at Half Maximum remains in the range 1 2 ot 1 4 pixels in most cases as shown in Figure 6 ISDC OMC Analysis User Manual Issue 5 0 11 OMC FM PSF li Neal on H normalized o ANI 65 52 39 26 13 0 39 x um 1 pix 13 um Fi 6 di OMC Point Spread Function The plot shows a fit to the avera
34. e of 5 cm diameter and a square field of view of 5 x 5 A Johnson V filter allows photometric calibration in a standard system An optical baffle ensures the necessary reduction of scattered sunlight and also the unwanted stray light coming from non solar sources outside the FOV The camera unit is based on a large format CCD 2061x1056 pixels working in frame transfer mode 1024x1024 image area and 1024x1024 storage area This design with a frame transfer time of around 2 ms allows continuous measurements and makes it unnecessary to have a mechanical shutter For pixel to pixel calibration purposes 2 Light Emitting Diodes LEDs are installed in the CCD cavity of the camera These LEDs illuminate the image area of the CCD The differential response of each pixel to this known illumination pattern is used to build a flatfield correction matrix required for photometric calibration of the images An overall cut out view of the instrument is given in Figure 1 3 2 The Optics The optical system as shown in Figure 2 consists of e a 6 fold lens system composed of two different types of radiation resistant glass e a filter assembly the Johnson V filter has been defined with a combination of 3 mm thick SCHOTT GG495 filter and 2 mm thick SCHOTT BG39 filter e alens barrel giving mechanical support to the lenses and ensuring their alignment 33 The CCD Detector A CCD consists of several hundred thousand individual picture elements pixels
35. e optical band simultaneously with those at hard X rays and gamma rays Multi band observations are particularly important in high energy astrophysics where variability is typically rapid unpredictable and of large amplitude Table 1 gives the main OMC parameters Table 1 OMC parameters and scientific performances Field of view Aperture Focal feng Optical throu Stray light reduction factor within UFOV Angular resolution 23 Gaussian PSF FWHM 1 3 4 Point source location accuracy Angular pbx size CCD pixels 2061 x 1056 1024 x 1024 image area 13 x 13m per pixel CCD Quan oa CCD Fall well capacity ADC levels 12 bit signal 4096 levels 30 cts digital level low gain 5 cts digital level high gain Frame transfer time 2 ms Time resolution Typical integration times Limit magnitude 10 x 200 s 3c 50 x 200 s 3c 100 x 200 s 30 Sensitivity to variations 10x100 s 30 Amy lt 0 1 for my lt 16 This parameter defines the factor by which the flux from any source within UFOV but outside FOV is reduced by multiple reflections before reaching the detector surface as background light The unobstructed field of view UFOV defines the angle which has to be clear to space in order to avoid reflected light directly reaching the optics ISDC OMC Analysis User Manual Issue 5 0 3 3 Instrument Description 3 1 The Overall Design The OMC optics are refractive with an entrance apertur
36. ed centroids i e the celestial coordinates in which the photometric apertures have been located to calculate the fluxes The error estimate corresponds to the accuracy of the WCS support derived for the faint photometric reference stars For faint scientific sources or for crowded fields the user should check if the derived coordinates actually correspond to its source Table 9 The o_src_get_fluxes parameters included in the main script Name Name Type Description main script executable W IMA_timestep timestep integer SHOT grouping bin length in seconds default 600 IMA_maxCentOff maxCentOff integer Maximum shift for re centering integration box possible values 0 1 2 default 2 IMA_numSigma numSigma integer Minimum standard deviations for peak search in re centering possible values O 10000 default 2 ISDC OMC Analysis User Manual Issue 5 0 33 IMA_maxshottime maxshottime integer IMA_minshottime minshottime integer IMA_usePrp usePrp boolean IMA_minBoxFrac minBoxFrac real IMA_minTimeFrac minTimeFrac real IMA_badPixels bdpxlpar string IMA noiseLowLeft noiseLowLeft real IMA noiseLowRight noiseLowRight real IMA _noiseHighLeft noiseHighLeft real IMA noiseHighRight noiseHighRight real IMA skyStdDev skyStdDev real Table 10 Possible values o_src_get_fluxes output OMC_PROBLEM_NONE OMC_PROBLEM_EXTRAPOLATED MAG 2 OMC_PROBLEM_BAD_CENTROID OMC_PROBLEM_BAD_PSF OMC_PROBLEM_ANOMA
37. ee 3 The OMC Analysis User Manual is divided into two major parts e Description of the Instrument This part based to some extent on the ISOC AO 2 document 2 introduces the INTEGRAL on board Optical Monitoring Camera OMC e Description of the Data Analysis This part starts with an overview describing the different steps of the analysis Then in the Cookbook Section several examples of analysis and their results and the description of the parameters are given Finally the used algorithms are described A list of the known limitations of the current release is also provided In the Appendix of this document you will find the description of the Raw and Prepared Data and also the description of the Scientific Products If you are interested in Data Structures not described in the Appendix go to the ISDC web page http isdc unige ch index cgi Data templates ISDC OMC Analysis User Manual Issue 5 0 1 Part I Instrument Definition ISDC OMC Analysis User Manual Issue 5 0 2 Scientific Performance Summary The Optical Monitoring Camera OMC is a wide field optical instrument using a large format CCD charge coupled device detector limited by a relatively low telemetry rate It measures the optical emission from the prime targets of the high energy instruments and also from the known optical sources in the field of view The OMC offers the first opportunity to make observations of long duration in th
38. eristics files IC files by hand the IC Master Group was created see more details in 1 The omc_science_analysis loops over all science windows in the observation group calling for each omc_scw_analysis script performing the actual analysis from the data correction to the source magnitudes calculation It is possible to run only a subset of the analysis The full information on the content of the input and output Data Structures is given in the Appendix During its work the omc_science_analysis script calls the following low level scripts e 0_cor_science e 0 gt e o_src_analysis In the following sections you will also find a more intensive discussion of the parameters included in the main script Note that the name of the main script parameters differs from the low level ones by the name of the level added to the low level script parameter name You can find information on all the parameters of any low level script or executable by typing in a command line the name of the executable with h after it e g o_cor_box_fluxes h 8 1 o0_cor_science This script calculates corrected pixel values for the subsequent analysis by removing the background coming from the electronics The data are converted from analog digital units ADU to electrons flatfielded corrected for bias and dark current with the executable e o_cor_bor_fluxes This executable performs Bias removal Dark Current removal and Flat Fielding In determining th
39. f 100 s This trigger mode will be active during the rest of the pointing as well as during subsequent pointings as long as the bursting source is in the OMC FOV The expected delay between the start of the burst and the start of OMC monitoring is less than 1 minute Specifically the OMC monitoring starts less than 15 seconds after the IBAS trigger This makes it possible to obtain slightly delayed but simultaneous optical X ray and gamma ray data of any burst taking place within the OMC FOV ISDC OMC Analysis User Manual Issue 5 0 8 5 Performance of the Instrument 5 1 Background and Read out Noise There are two main sources of background flux for OMC both related to the rather large angular pixel size of 17 504 x17 504 scattered sunlight zodiacal light and unresolved stellar sources Maximum background conditions correspond to pointings towards the galactic plane with maximum zodiacal light while the mini mum background is achieved around the galactic pole with minimum zodiacal light The left side of Figure 4 shows the average number of stars brighter than a given magnitude expected to be contained within a single OMC pixel It can be seen that on average no source confusion is expected for objects brighter than my 17 at any galactic latitude For my 18 0 source confusion becomes problematic in regions very close to the galactic plane It is important to stress that on the galactic plane we expect to have on average more th
40. f line Scientific Analysis 48
41. g information from the surrounding pixels and potentially from the column containing the source but no damage is expected on the detector The left side of Figure 5 shows the expected number of counts on the CCD as a function of V magnitude for a 10 s integration This number corresponds to the counts expected in the central brightest pixel only Finally the right side of Figure 5 gives the integration time at which stars of different magnitudes start to saturate the CCD 5 4 Photometric Accuracy Table 2 shows the expected error expressed in magnitudes of a given measurement for the quoted integration time and magnitude Effective integration time means the total exposure after combining several shots The value of 300 s corresponds to the typical effective exposure obtained by OMC Standard Analysis using default parameters A value of 900 s corresponds to the maximum effective exposure one can get in the OMC standard analysis when changing the default parameters An effective exposure of 900 s is also a representative value for an entire 5 x 5 dither pattern 2000 s pointing Of course these values should be used as a guide they are the best values which can be obtained with the latest version of analysis software and are only valid for isolated stars in the staring mode The values for photometric accuracy have been computed by taking into account the most current knowledge of the OMC instrument One can see in Table 2 th
42. ge PSF measured under different conditions The FWHM remains in all cases below 1 3 pixels More than 90 of the energy falls within a region of 3 x 3 pixels ISDC OMC Analysis User Manual Issue 5 0 12 Part II Data Analysis ISDC OMC Analysis User Manual Issue 5 0 13 6 Overview As it was said in the previous part see Sections 4 1 4 2 during science mode the OMC takes images of the full field of view every 1 to 255 seconds depending on the integration time for the different targets Each individual OMC CCD integration for image generation is called a shot The full image or a section is transferred to the data processing electronics Due to TM constraints only a number of sub windows typically of 11x11 pixels are extracted around the positions of objects of interest About 100 such windows are extracted for exposures of 100 s In the following the term box is used for such a sub window for clarity In the Data Preparation step of the automatic processing at ISDC the OMC raw data are compared with the available planning data In addition the measured fluxes of individual pixels and the fluxes averaged over boxes are compared with given limits Shots and boxes that deviate from the planning data are flagged accordingly Boxes are also flagged for unusually low fluxes or signs of saturation All this information is used by the scientific analysis software to exclude whole shots or individual boxes wh
43. h default 1 effective mode of those parameters whose mode is set er to a auto trigger triggersize integer attach boolean clobber boolean chatty integer mode string ISDC OMC Analysis User Manual Issue 5 0 37 8 4 omc_obs_analysis This script runs wrap up tasks on a full Observation Group with OMC data Currently only the tool o src_collect is called 8 4 1 o_src_collect This executable combines source data including derived fluxes and magnitudes distributed over several Science Windows into a single table See Cookbook Section 7 for an example Table 13 The o_src_collect parameters string DOL of group from which OMC results are read This can either be an Observation Group or a Science Win dow Group though the latter option is rarely useful results string Name of the output FITS file including the fits ex tension with combined results select string CFITSIO selection string applied to input tables default no selection attach boolean Attach resulting table to group If set to yes the newly created table will be attached to the input group possible values y n default n chatter integer Verbosity of the output possible values 0 3 default 1 ISDC OMC Analysis User Manual Issue 5 0 38 9 Known Limitations 1 The automatic extraction of fluxes and magnitudes produce reliable
44. he source magnitudes are derived With default parameter settings the images are created only if during the observation an IBAS trigger occurs In this case a small image typically 81x81 or 91x91 pixels around the IBAS position for a possible burster is created IMA2 Results Collection As explained in 1 within the ISDC Data Model the data concerning one observation are distributed between different files All the data from one pointing a period during which the spacecraft axis pointing direction remains stable or slew a period during which the spacecraft manoeuvres from one stable position to another are grouped to so called Science Windows Groups The observation usually contains more than one Science Window and all the data related with the observation are grouped to an Observation Group At the IMA2 level the results distributed over several Science Windows are collected into a single table ISDC OMC Analysis User Manual Issue 5 0 15 7 Cookbook This chapter describes how to use the OSA OMC software on the extended Crab source It covers the following steps e Setting up the analysis data e Setting the environment e Launching the analysis e Interpreting the results We assume that you have already successfully installed the ISDC Off line Scientific Analysis OSA Software version 5 0 The directory in which OSA is installed is referred later as the ISDC_ENV directory If it is not the case look at the Installa
45. ich have been flagged as bad during Data Preparation or which fall outside user limits for their properties As it was explained in the Introduction to the INTEGRAL Data Analysis 1 the scientific analysis of all the INTEGRAL instruments is split into a number of steps with similar tasks The scientific analysis of the OMC data is the least complex of all the INTEGRAL instruments The main script omc_science_analysis includes four main steps see Figure 7 omc_science_analysis omc_scw_analysis Data Correction o_cor science corrected data Good Time Handling Good Time Intervals Source Flux Reconstruction Source fluxes o_src_analysis E and magnitudes Image Creation sky images Combined fluxes Results Collection omc_obs_analysis 7 and magnitudes Figure 7 Overview of the OMC science analysis ISDC OMC Analysis User Manual Issue 5 0 14 COR Data Correction At this step the appropriate calibration data dark current bias flatfield for the current science window group are selected and the corrected pixel values for the subsequent analysis are calculated GTI Good Time Handling At this step Good Time Intervals GTI for the current Science Window are derived based on housekeeping data and attitude stability information IMA Source Flux Reconstruction and Trigger Image Creation At this step the fluxes as well as normal and fast mode images of the individual sources are calculated and t
46. ky background If this is exceeded this is flagged in the PROBLEMS column see Table 10 but the flux calculation continues BOX Quality checks ISDC OMC Analysis User Manual Issue 5 0 32 e entire box within CCD area e box is at the planned position e box size is as planned e box type is the planned type e no box pixels are saturated Shot Quality Checks e shot is the planned type e the Shot resides within Good Time Intervals e the shot gain is the planned gain e the time and number_of boxes fractions are above the minimum required e user can define the minimum shot times This is useful to select only shots with sufficient exposure for a significant flux detection of a source of interest e user can define the maximum shot times This is useful to avoid shots where the subwindow is saturated for a source of interest o src_get_fluxes determines e flux of all objects of interest over 1x1 3x3 and 5x5 pixel areas centered on the source Fig 13 e the error on the 1x1 3x3 and 5x5 determined fluxes e sky background and its error for each source e effective PSF width for each source e centering off sets with respect to the centre of the central pixel This gives the real position on the CCD in which the photometric apertures have been located to calculate the fluxes e derived right ascension and declination RA_FIN and DEC_FIN with their error estimates These co ordinates correspond to the comput
47. l User Interface GUI see Fig 8 and you have a chance to check the parameter settings In Table 3 we list all the parameters of the main script with a brief explanation The main panel of the GUI shows only the most important parameters of the script These parameters are marked in bold in the Table To access the other parameters click on the hidden button in the GUI main panel Once you are satisfied with your settings save them by pressing the Save button and then press Run to start the data reduction The detailed description of the main script structure and algorithms is given in Section 8 Table 3 Parameters for the omc_science_analysis omc_science_analysis ogDOL string DOL of Observation Group to be analyzed default og_omc fits GROUPING startLevel string Analysis level at which analysis begins possible values COR IMA2 default COR endLevel string Analysis level at which analysis finishes possible values COR IMA2 default IMA ISDC OMC Analysis User Manual Issue 5 0 19 chatter IC_Group IC_Alias COR flatField COR darkCurrent COR_biastime COR _kscKappa COR_higain COR_lowgain integer string string string string integer integer real real Verbosity level of the outputs possible values 0 3 with 1 as normal default 1 DOL of the Instrument Characteristics master group This group is accessed b
48. l area Flag for various problems Read out noise in e low gain left ROP Read out noise in e low gain right ROP Read out noise in e high gain left ROP Read out noise in e high gain right ROP Derived X axis offset of the source from the box centre Derived Y axis offset of the source from the box centre Effective PSF FWHM in pixels X coordinate of the lower left pixel of the target box Y coordinate of the lower left pixel of the target box Rank CUR_TABLE 1 57 TAR_RANK Derived right ascension in degrees Standard error for RA_FIN cos DEC_FIN Derived declination in degrees Standard error for DEC_FIN ISDC OMC Analysis User Manual Issue 5 0 47 References 1 ISDC OSA INTRO Introduction to the INTEGRAL Data Analysis http isdc unige ch Soft download osa osa doc osa_doc 5 0 0sa um intro 5 0 index html http isdc unige ch Soft download osa osa doc osa doc 5 0 0sa_um intro 5 0 index html 2 OMC observer s manual http www rssd esa int Integral AO3 A03_ OMC_om pdf 3 OMC Analysis Scientific Validation Report http isdc unige ch Soft download osa osa_doc osa_doc 5 0 osa sci_val_omc 3 3 pdf http isdc unige ch Soft download osa osa_doc osa_doc 5 0 osa_inst_guide 2 0 html 5 OMC catalogue e ftp ftp laeff esa es pub integral catalogue e http sdc laeff esa es omc ISDC OMC Analysis User Manual Issue 5 0 4 ISDC OSA INST GUIDE Installation Guide for the INTEGRAL Of
49. lculated 16384 Source is extended flux not valid This executable calculates magnitudes from fluxes for all good sources in the Science Window Group The executable works on each output table containing the fluxes associated with a single photometric point for every source in the Science Window Group The executable accomplishes this by extracting the flux for each source in a single table and applying a flux to magnitude conversion Parameter IMA_magboxsize defines the area attributed to the source You can define whether photons from the central point only or also photons ISDC OMC Analysis User Manual Issue 5 0 34 from 3x3 or 5x5 area are coming from the source If the real signal to noise ratio is less than the value given in the minSNR parameter it is flagged in the PROBLEMS column of OMC SRCL RES value 8192 and both MAG_V and ERRMAG are set to a value of 99 The errors analysis considers Poissonian errors read out noise sky background noise and Photometric Cal ibration noise Table 11 The o_src_compute_mag parameters included in the main script Name Name Type Description main script executable IMA_magboxsize magboxsize integer Defines the area attributed to the source when calcu lating the default magnitude column MAG_V How ever MAG_V1 MAG_V3 and MAG_V5 are also com puted and they correspond to the magnitude derived by using the 1x1 3x3 and 5x5 flux areas respec tively Possible values
50. libration data available This will not be possible for the trigger images for which PRP is the highest level available If the requested level is at least PRP 0_tma_build will compute and store as an image keyword the barycentric time for the first data element beginning of the shot Please note that because the barycentric correction depends on the source position on the sky the computed barycentric time corresponds to the coordinates of the centre of the OMC FOV If the user is only interested in processing one source he she can give its OMCID and build small images containing only the box corresponding to the selected source For extended sources or for sources generating several boxes mosaic the image will be created containing the mosaic of boxes o_ima_build can be launched from omc_science_analysis to process an OG or omc_scw_analysis to process a SWG In both cases o_ima_build will store the zero point in magnitudes as an image keyword CALZERO If the images were created with level COR then the V magnitude can be calculated as V CALZERO 2 5 x log TotalCounts INT_TIME where TotalCounts means the total number of counts e for the given source and INT_TIME is the integration time Note that if the level of the images is not COR the user must correct for bias dark current and flatfield before applying the above magnitude relation All parameters in o_ima_build are also available from omc_science_analysi
51. minimize the residuals in each pixel according to a Gaussian PSF profile The fitted values are the centroid X and Y coordinates and the PSF width e For each source a small dependence of the PSF width on the X Y pixel coordinates is corrected by applying a linear relation e Compute the centroids of all scientific targets by using an iterative method similar to the one described for computing the PSF However in this case the PSF width is supposed to be known and fixed e Calculate the flux using three different apertures 1x1 3x3 and 5x5 pixel areas In 3x3 and 5x5 apertures partial pixels are used dividing each real pixel in 4 sub pixels The areas are circularized ISDC OMC Analysis User Manual Issue 5 0 31 removing the corners in 3x3 and 5x5 giving effective apertures of 8 and 19 square pixels respectively The effective apertures are centered on the computed centroids e Perform aperture corrections in each one of the computed fluxes 1x1 3x3 and 5x5 e Detect source contamination non point sources saturated sources or wrong sources by analysing the shape of the PSF These cases are flagged in the PROBLEMS column The algorithm used to compute the fluxes takes into account the following effects e Dependence of the PSF on lense temperature and satellite attitude which is difficult to fit by a model e Dependence of the PSF on the pixel location over the CCD detector The relation is linear so the de
52. n ADU A 2 Prepared Data The ScW Pipeline processes the raw data converting the local on board time to the full on board time and comparing the observed shots and boxes with the planning information sent to the OMC The planning information is used in the following analyses for the precise information of the source positions This pipeline also checks the box and pixel fluxes against limits to flag suspiciously high or low values The results of the processing of the raw data for the science mode are written to the data structures OMC SHOT PRP and OMC BOXS PRP see Tables 17 and 18 These data structures have a structure similar to the one for the RAW data Table 17 Content of OMC SHOT PRP Data Structure OBT_ACQ On board time of data acquisition INT_TIME Effective integration time BOX_PLAN BOX_FRAC TIMEFRAC PLAN_OK TYPE_OK GAIN_OK SHOTTYPE FIRSTBOX NUMBOXES The number of boxes planned for this shot The fraction of observed boxes vs planned Fraction of observed planned integration time Has this shot planning data O no 1 yes Shot type agrees with planning 0 no 1 yes Target gain agrees with planning 0 no 1 yes Shot type 1 photometry 2 science Position of first box of this shot in OMC BOXS PRP Number of boxes belonging to this shot Table 18 Content of OMC BOXS PRP Data Structure MEANFLUX Mean flux of box in ADU STDDEV Standard deviation of flux distribution within box FLUXLEVL Flag to
53. n to the single format is necessary The meaning of all the columns is given in Table 29 Section C 4 Due to the non uniformity of the Crab background in the frame surrounding the 5x5 area see Figure 13 the computed error bars are rather large If the IBAS trigger occurs during the observation the small image typically 81x81 or 91x91 pixels around the IBAS position for a possible burster is downloaded The resulting image is created at the IMA level ISDC OMC Analysis User Manual Issue 5 0 22 omc_science_analysis DOL 0g_omc fits GROUPING browse Figure 8 GUI for OMC analysis This process is controlled with the parameter IMA_triggerImage which is set to yes by default If another parameter IMA_scienceImage is set to yes a file with one image per shot in the Science Window will be created This file can be large a few Megabytes per shot and we have a few dozen of shots typically so the default value of this parameter is no However with the o_ima_build program you can select shots for which you would like to build an image with the boxes located in their real position on the OMC CCD For example let us first create using the corrected data datalevel COR a fits file FullField fits which will contain 7 images of the full OMC field of view for shots 11 to 17 in Science Window 010200210010 o_ima_build inswg scw 010200210010 000 swg_omc fits 1 outfitsname FullField fits datalevel COR
54. ngs of the IC files and the reference catalogue Just follow these instructions When an analysis script asks you to specify the DOL you should specify the path of the corresponding FITS file and the corresponding name or number of the data structure in square brackets do not forget that numbering starts with 0 See more details in the Introduction to the INTEGRAL Data Analysis 1 Please note that the naming scheme is different for revision 1 and revision 2 data For the revision 1 data the name of the prepared Science Window Group is swg prp fits instead of swg fits ISDC OMC Analysis User Manual Issue 5 0 17 7 2 Setting the environment Before you run any OSA software you must also set your environment correctly The commands below apply to the csh family of shells i e csh and tcsh and should be adapted for other families of shells In all cases you have to set the REP_BASE_PROD variable to the location where you perform your analysis e g the directory omc_data rep Thus type setenv REP_BASE_PROD PWD Then if not already set by default by your system administrator you should set some environment variables and type setenv ISDC_ENV directory_of_OSA_sw_installation setenv ISDC_REF_CAT REP_BASE_PROD cat hec gnrl_refr_cat_0020 fits 1 source ISDC_ENV bin isdc_init_env csh The idea is to e set ISDC_ENV to the location where OSA is installed e set ISDC_REF_CAT to the DOL of the ISDC Reference Catalog e
55. ounterparts of gamma ray sources ISDC OMC Analysis User Manual Issue 5 0 7 e Most known optical counterparts of X ray sources e X ray sources detected and catalogued by ROSAT e Quasars observable with OMC e Additional known AGNs e Known eruptive variable stars including novae and cataclysmic e Variable objects which may require an additional optical monitoring e HIPPARCOS reference stars for positioning and photometric calibration During the mission additional sources of interest will be added to the catalogue namely e Newly discovered optical counterparts of high energy sources especially sources discovered during the Galactic Plane Survey e Regions of special interest for INTEGRAL science e New supernovae e New eruptive variable stars e Any other Target of Opportunity TOO For each scheduled observation the coordinates of all the targets of interest within the corresponding field of view are extracted from the OMC input catalogue 4 4 Gamma Ray Bursts and transient sources The INTEGRAL Burst Alert System IBAS is searching for gamma ray bursts GRB using IBIS ISGRI events If IBAS detects a GRB within the OMC FOV a near real time command will be sent to OMC Upon reception of this telecommand OMC stops the observations planned for this pointing and starts to monitor a single window of 91x91 pixels 24 x 24 around the region where the burst has been detected with a fixed integration time o
56. run the OSA set up script isdc_init_env csh which initializes further environment variables relative to ISDC_ENV Besides these mandatory settings there are two optional environment variables COMMONLOGFILE and COMMONSCRIPT which are useful e By default the software logs messages to the screen STDOUT To have also these messages in a file i e common_log txt and make the output chattier use the command setenv COMMONLOGFILE common_log txt e As your level of expertise with the software increases you may wish to not have the GUIs pop up when you launch your analysis In this case the variable COMMONSCRIPT must be defined setenv COMMONSCRIPT 1 To revert to having the GUI unset the variable unsetenv COMMONSCRIPT 3If the setenv command fails with a message like setenv command not found or setenv not found then you are probably using the sh family In that case please replace the command setenv my variable my value by the following command sequence my variable my value export my variable In the same manner replace the command source my script by the following command my script the is not a typo 4For example the exit status of the program will now appear ISDC OMC Analysis User Manual Issue 5 0 18 7 3 A Walk Through the OMC Analysis After setting up the data and the environment you are ready to call the analysis script on the Crab region observations defined
57. s and omc_scw_analysis The user can use both scripts to build the images only see IMA_onlyImage IMA scienceImage and IMA triggerImage parameters Table 12 The o_ima_build parameters inswg string DOL for input Science Window Group outfitsname string Output name of FITS file including the fits extension datalevel string Level of the original data possible values RAW PRP COR startshot integer Starting shot number to be processed Note that startshot 1 means the first shot appearing in the SWG In general the first shot will not have SHOT_ID 1 possible values 1 9999 default 1 endshot integer Ending shot number to be processed possible values 0 9999 0 corresponds to the last shot in the Sew default 0 ISDC OMC Analysis User Manual Issue 5 0 36 boolean Use trigger data to build image possible values y n default n Size of the trigger window in pixels only used when trigger yes The value of this parameter MUST be the same as used on board The images built when trigger data are used will be as large as triggersize x triggersize possible values 1 91 default 81 Attach output data structure to the input SWG De cides if output index OMC SKY IMA IDX will be attached to the input SWG default no Clobber existing output data structures default no Level of chattiness for the executable possible values 0 3 0 very low 3 very hig
58. s taken Time of the first data element Barycentric time for the first data element Elapsed time of the integration in seconds Effective integration time in seconds Type of shots used for building integration OMC catalog source identifier Target type Science Photometric Source right ascension in degrees Source declination in degrees Flux in electron s derived from 1x1 integration boxes Error estimate for FLUX_1 Flux in electron s derived from 3x3 integration boxes Error estimate for FLUX_3 ISDC OMC Analysis User Manual Issue 5 0 46 FLUX_5 ERFLUX_5 SKYBACK SKYERROR SIZE_MAG MAG_V ERRMAG_V CATMAG_V CATERR_V MAG_V1 ERMAG_V1 MAG V3 ERMAG_V3 MAG_V5 ERMAG_V5 PROBLEMS NOISE_LL NOISE_LR NOISE_HL NOISE_HR CENTRING_X CENTRING_Y PSF_FWHM X_TAR Y_TAR RANK RA_FIN RA_FIN_ERR DEC_FIN DEC_FIN_ERR Flux in electron s derived from 5x5 integration boxes Error estimate for FLUX_5 Mean flux from sky background in electron pixel s Error estimate for SKYBACK Integration box size for deriving MAG_V Computed V Johnson magnitude Error estimate for V magnitude Catalog V Johnson magnitude Catalog error estimate for V magnitude Computed V magnitude for the 1x1 pixel area Error estimate for V magnitude in 1x1 pixel area Computed V magnitude for the 3x3 pixel area Error estimate for V magnitude in 3x3 pixel area Computed V magnitude for the 5x5 pixel area Error estimate for V magnitude in 5x5 pixe
59. t 0 9 Minimum fraction of planned time actually observed possible values 0 1 default 0 99 Use prepared data for quality checking default yes ISDC OMC Analysis User Manual Issue 5 0 21 IMA_badPixels string DOL of Bad Pixel Table take from IC default IMA_photCal string DOL of photometric calibration curve take from IC default gt 7 4 Results The files containing results of the OMC analysis are written into the directory REP_BASE_PROD scw sepa rately for each Science Window RRRRPPPPSSSF is the number of the Science Window scw RRRRPPPPSSSF omc_intg_res fits scw RRRRPPPPSSSF omc_srcl_res fits The first file omc_intg_res fits contains the description of the integration periods chosen by the program The column TELAPSE gives you the elapsed time covered by the integration The time of the integrations depends on the type of the shots given in the column SHOTTYPE it is close to the value defined by the parameter IMA_timestep 600 seconds in a given example for the science shots SHOTTYPE 2 and much smaller for the photometry shots SHOTTYPE 1 see Section 8 3 for more details The second file omc_srcl_res fits contains a table with information on the source fluxes each row corresponds to one target box Detailed information on the content of the output files is given in the appendix Section C Combined results are written to the file
60. t_fluxes parameters included in the main script o a 33 Possible values in PROBLEMS column in the o_src_get_fluzes output 34 The o_src_compute_mag parameters included in the main script 35 The dima bud Parametros AA A a ME eee ERE Be 36 The o se pallet parameters cier ee pa EERE Eee a aa a 38 Content of OMC SHOT RAW Data Structure e 40 Content of OMC BOXS RAW Data Structure 2 2 o 40 Content of OMC TRIG RAW Data Structure o o a 41 Content of OMC SHOT PRP Data Structure 41 Content of OMC BOXS PRP Data Structure o 41 Content of OMC TRIG PRP Data Structure e 42 Content of OMC DARK CAL Data Structure o 43 Content of OMC BDPX CAL Data Structure a 43 Content of OMC PHOT CAL Data Structure e e 43 Content of OMC GOOD LIM Data Structure 2 2 e 43 Content of OMC SHOT COR Data Structure 2 0 0 0 2 02 0020 0000 44 Content of OMC GNRL GTI Data Structure l aoaaa ee ee 44 Content of OMC SRCL RES Data Structure ee ee ee 44 Content of OMC INTG RES Data Structure 2 a 45 Content of OMC SKY IMA IDX Data Structure 2 2 o a 46 Content of OMC STAN RES Data Structure o 46 ISDC OMC Analysis User Manual Issue 5
61. tector is probably slightly tilted e Changes of the sources centroid with time due to OMC thermoelastic deformations as well as the variation of lense temperature e Contamination by close sources The photometric apertures that are used attempt to keep the effect of companions on the derived fluxes as constant as possible The World Coordinate System WCS support is derived by fitting the best astrometric solution to the faint photometric reference stars A new solution is computed for each effective integration This corrects the inaccuracy due to the thermoelastic deformations which affect the alignment of the OMC optical axes with the spacecraft attitude reference Issues deemed to affect the quality of the standard pipeline analysis of individual sources are flagged in the PROBLEMS column of OMCSRCLRES and OMCSTANRES They are stored in an Unsigned Integer Register any problem encountered is logically AND ed to the existing register value Deconstruction of the total into its only possible component values reveal the individual PROBLEMS see Table 10 for the possible values in the PROBLEMS column 11 7 3 1 11 7 51 3 1 background Figure 13 Illustration of the geometry defining the background and source magnitude calculation o src_get_fluxes performs the following quality checks e User defines maximum acceptable Standard Deviation on s
62. tegration time and reanalyze the data rejecting the shots with the longest integration times 6 Due to thermoelastic deformations the alignment of the OMC optical axis with the S C attitude reference after correcting the OMC misalignment may diverge by up to 30 2 pix From OSA 5 0 onwards the derived coordinates are corrected at the time of computing the WCS support by using the photometric reference stars giving an accuracy better than 2 in most cases ISDC OMC Analysis User Manual Issue 5 0 39 A Low Level Processing Data Products A l Raw Data As it was said in the previous part see sections 4 1 4 2 during science mode the OMC takes images of the full field of view every 1 to 255 seconds depending on the integration time for the different targets Each individual OMC CCD integration for image generation is called a shot The baseline is to follow a given sequence of different integration times within these limits in order to monitor both bright and faint sources within the FOV this sequence is configured just before the science mode is entered using a dedicated telecommand The full image or a section is transferred to the data processing electronics Due to TM constraints only a number of sub windows typically of 11x11 pixels are extracted around the positions of objects of interest About 100 such windows are extracted for exposures of 100 s In the following the term box is used for such a sub windo
63. then a check for Trigger Mode data will be done and if some are found o_ima_build will be run to create real 81x81 or 91x91 pixel images around the IBIS alert trigger system IBAS position for a possible burster If the script parameter IMA_scienceImage is set to yes then a file with one image per shot in the Science Window will be created This file can be large a few Megabytes per shot and we have a few dozen of shots typically so the default value is no One can also restrict the analysis on the IMA step to image creation only without subsequent analysis by setting the trigger IMA_onlyImage to yes The output data structures are described in Section C 3 8 3 1 o_src_get_fluxes This executable calculates flux values for all good photometry and science sources in the Science Window Group SWG Several shots are combined within a given time interval in order to obtain significant results for weak sources Photometry shots SHOTTYPE 1 are co added in contiguous groups found in the SWG whereas science shots SHOTTYPE 2 are co added to an integration time in seconds specified by the timestep parameter The timestep is used only as a guide integration time by o_src_get_fluxes which calculates a real timestep to provide a number of co added shot groups as close to the input timestep as is possible Note that while in the photometric shots SHOTTYPE 1 the targets are only bright photometric sources TYPE_
64. tion Guide for the INTEGRAL Off line Scientific Analysis 4 for detailed help 7 1 Setting Up the Analysis Data In order to set up a proper environment you first have to create an analysis directory e g omc_data_rep and cd into it mkdir omc_data_rep cd omc_data_rep setenv REP_BASE_PROD PWD This working directory will be referred to as the REP_BASE_PROD directory in the following All the data required in your analysis should then be available from this top directory and they should be organized as follow e scw data produced by the instruments e g event tables cut and stored by ScWs e aux auxiliary data provided by the ground segment e g time correlations cat ISDC reference catalogue e ic Instrument Characteristics IC such as calibration data and instrument responses e idx set of indices used by the software to select approriate IC data The OMC example presented below is based on observations of the Crab from Revolution 102 Part of the required data may already be available on your system In that case you can either copy these data to the relevant working directory or better create soft links as follow ln s directory_of_ic_files_installation__ ic ic ln s directory_of_ic_files_installation__ idx idx ln s directory_of_cat_installation__ cat cat ln s directory_of_local_archive__ scw scw ln s directory_of_local_archive__ aux aux The Instrument Characteristics files O
65. ult 0 Maximum allowed shot integration time Shots with longer inte gration times will be skipped default 300 Maximum shift for re centering integration box If this is larger than zero a search for the brightest pixel within this range around the box center is done and the integration box is centered on that pixel This allows to cope with the fact that even under optimal circumstances not all sources are perfectly centered in their subwindows possible values 0 1 2 default 2 Minimum standard deviations for peak search in re centering possible values 0 10000 default 2 Integration box size for deriving magnitudes possible values 1 central pixel 3 3x3 area 5 5x5 area default 5 Maximum acceptable Standard Deviation on sky background default 10 0 Make image if trigger data found in SWG default yes Make image of science data found in SWG default no minimum acceptable signal to noise ratio default 1 0 Read out noise in e for low GAIN left read out port possible values 0 10000 default 45 Read out noise in e for low GAIN right read out port possible values 0 10000 default 49 Read out noise in e for high GAIN left read out port possible values 0 10000 default 33 Read out noise in e for high GAIN right read out port possible values 0 10000 default 35 Minimum fraction of planned boxes actually observed possible values 0 1 defaul
66. viations 00 aa AAA RRA es a A E AAN 1 orar So a a ek ee oo ede we a eS OEE aed 4d bod od I Instrument Definition 2 Dclentine Performance SUMMALY coros Ree aa a Oe OG eee ee eS 3 Instrument Description sr eaa a ek a Rees oe He a a Gite a 3 1 The Overall Decidi o a eg ok AS oR a AA A a BY 3 2 TREUD 8 4 4 6444 2a A nook aa AEE a A ed G 3 3 MRO COW Detector osae as a rra aa e aaa 4 Instrument Operations e 44 aora a A REE A SS EE AE 4 1 Normal Science Operations Mode eco e sa aaacasa ee ek ee ee a RO 4 2 Fast Monitoring Mode a osr ia eee es ass aaa 4 3 The OMC Input Catalogue lt s o u aaoi Tidi a A a e e 4 4 Gamma Ray Bursts and transient sources oo a 5 Performance of the Instrument se soci 644 2b SHEERS ee ee ee as 5 1 Background and Read out Noise anaa aaa eee ee ees 5 2 Liming Faint Mesuitude aceras a a ne AAA 5 3 Limiting Bright Magnituda cecs o s w y e 24h 4 OP Ye ee ee ae we ee a 5 4 Photometric Accuracy ooo 2464 344 DLA aA OER a eae eee da 5 9 POCHSINE oe a a a iia A ee amp II Data Analysis 6 OWSETES ioeie a SS aa e ee HA ERE ERO a h dl A S 2 7 ORO y ds eee a GA a a dd ee EE ia Id a dd fall Setting Up the Analysis Data o s o g ooe mo aei d aa a Ce ee dG eee enw ed 1 1 Downloading Your Data lt a sari ada aasad a A as 72 Setting the environment e 7 3 A Walk Through the OMC Analysis e e eee ee eee 7 4 BOSES ua podata a e e a RY Be a el ee RR Ee 8 Basie Data
67. w for clarity The information from such boxes is transferred to the Earth and added to the OMC SHOT RAW and OMC BOXS RAW see Tables 14 and 15 OMC SHOT RAW is a binary table with information about all shots in the given Science Window see Table 14 Each row in the table corresponds to one shot The information concerning the boxes transferred during the given shot and the measured data is located at OMC BOXS RAW data structure Each row in this binary table corresponds to one box Table 14 Content of OMC SHOT RAW Data Structure SHOT_NUM Counter of recorded shots SHOT_SEQ Shot sequence number SHOT ID Shot identification LOBT_ACQ Local on board time of data acquisition RAW_INTT Raw integration time as measured on board OFFSET_X Centering offset in X direction OFFSET_Y Centering offset in Y direction ERROFF_X Centering error in X direction in pixel ERROFF_Y Centering error in Y direction in pixel NUMCSTAR Number of stars used in the centering error determination GAIN Gain setting flag 0 low 1 high see Section 3 3 READOUT Read out port flag 0 left 1 right FIRSTBOX Position of first box of this shot in OMC BOXS RAW NUMBOXES Number of boxes belonging to this shot Table 15 Content of OMC BOXS RAW Data Structure SHOT_NUM Counter of recorded shots used for cross reference SHOT_SEQ Shot sequence number used for cross reference SHOT_ID Shot identification used for cross reference RANK The identification
68. wed 4 values of increasing importance MAX_VAL Maximum values allowed 4 values of increasing importance GTINAME Name of the group to which the parameter belongs SUB_ASSEMBLY Identifier of the instrument sub assembly CHECK_MODE Modes in which the parameters must be checked ISDC OMC Analysis User Manual Issue 5 0 43 C Science Data Products C 1 o0_cor_science At this step pixel values are corrected for the background coming from the electronics The resulting corrected data are written to the OMC BOXS COR and OMC SHOT COR data struc tures OMC BOXS COR contains the corrected pixel values in electrons for all boxes of a given shot Each row of this binary table contains data for one box Data in OMC SHOT COR tells you which boxes in OMC BOXS COR correspond to a given shot Table 24 Table 24 Content of OMC SHOT COR Data Structure FIRSTBOX Position of first box of this shot in OMC BOXS COR NUMBOXES Number of boxes belonging to this shot BIAS_LEVEL Bias level value for this shot BIAS_STDDEV Bias level standard deviation C 2 o_gti This script derives good time intervals based on housekeeping data information about satellite stability and data gaps The results are written to the data structure OMC GNRL GTI containing the good time intervals for the OMC and to the OMC GNRL GTI IDX the index of all OMC GNRL GTI data structures Table 25 Content of OMC GNRL GTI Data Structure Description
69. y means of a passive radiator illustrated in Fig 1 to an operational temperature in the range between 100 C to 70 C ISDC OMC Analysis User Manual Issue 5 0 4 es a Cover Focal Plane TDS ONE Aro User Manual gt Assy iPof the OMC Camera Unit CZ ZIY y A Fi 2 de Optical system layout 1 filter assembly housing 2 7 lenses 8 lens barrel 9 14 spacers 15 17 retainers 18 aperture stop Z Sun OMC m Right Read Out Port A IBIS 127 127 24 2 X_TAR Y_TAR 1047 1025 SCZ Star OMC Left Read Out Port tracker 24 2 X_TAR SCY x i Y_TAR 1047 1025 JMX2 DETX cathode la Calibration Sources XQ DETY backplane al X pointing Figure 3 5 Spacecraft amp Instrument Coordinate Systems Note that the X axis of the spacecraft is defined by the pointing direction ISDC OMC Analysis User Manual Issue 5 0 6 4 Instrument Operations Because of telemetry constraints only 2 2 kbps are allocated to OMC it is not possible to transmit the entire OMC image to the ground For this reason windows are selected around the proposed gamma ray target as well as other targets of interest in the same field of view The observers obtain the data pertinent to their target as well as all the other OMC CCD sub windows taken during the observation These additional targets are automatically selecte
70. y the script to find the calibration data relevant for the current Science Window default idx ic icmaster file fits 1 Selection alias for Instrument Characteristics By changing this alias different instances of IC data can be selected default OSA ters specific to COR level DOL of flatfield image take from IC default DOL of dark current amp bias calibration table take from IC default Integration time in sec for bias derivation possible values 0 100000 default 630 Number of Standard Deviations for KSC algorithm possible values 1 10 default 3 Multiplication factor for conversion to electrons for high gain default 5 0 Multiplication factor for conversion to electrons for low gain default 30 0 Parameters specific to GTI level GTI_gtiOmcNames GTI_gtiScNames GTI_omclimit Table GTI sclimitTable GTL att Tolerance GTI_BTIDol GTI_BTI_Names GTI_gtiUser GTI_TimeFormat GTI_Accuracy string string string string real string string string string string Names of OMC GTIs to be merged empty use default default gt Names of spacecraft GTIs to be merged empty use default default gt DOL of table with the OMC parameter limits take from IC file default DOL of table with spacecraft parameter limits take from IC file default Accepted attitude variability

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