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TCS User Manual

1. The remaining autoguiders see AGSELECT are fixed and the PROBE command is rejected if they are selected Keywords None Examples PROBE 10000 10000 Comments At the Cassegrain focus the autoguider can rotate with respect to the field and guiding errors will be applied incorrectly unless the PROBE command is issued At the other relevant focal stations it is only required by the AGVIEW command 4 51 PROPER_MOTION Enter proper motions into the edit source block Format PROPER MOTION lt pm_in ra gt lt pm in dec gt Defaults Unspecified proper motions are assumed to be 0 Parameters The proper motion in right ascension and declination in units of seconds year and arcseconds year respectively Limits 20 to 20 s year in RA 100 to 100 arcsec year in declination Keywords None Examples PROPER MOTION 1 54 0 675 Comments The synonym PM can also be used 4 52 RA Enter a right ascension in the edit source block Format RA lt ra_hours gt lt ra_minutes gt lt ra_seconds gt Defaults None Parameters The right ascension in hours minutes and seconds of time The right ascension is rejected if the any of the components lie outside the following ranges ra_hours 0 to 23 inclusive ra_minutes 0 to 59 inclusive ra_seconds 0 0 to 59 99 inclusive Keywords None Examples RA 12 34 56 789 4 53 RADIAL_VEL Enter a radial velocity in the edit source block Format RADIAL VEL l
2. GEARyymmdd DAT azimuth gear altitude gear TAPElyymmdd DAT azimuth tape head altitude gear TAPE2yymmdd DAT azimuth tape head 2 altitude gear TAPE3yymmdd DAT azimuth tape head 3 altitude gear TAPE4yymmdd DAT azimuth tape head 4 altitude gear The function key F10 is equivalent to the POINT command Although the tape encoder values are logged the data is not valid since the tape encoder counter boards have been removed 4 47 POLE Input values of polar motion Format POLE lt x _position gt lt y position gt Defaults None See comments below 29 WHT TCS 9 issue 3 3 WHT TCS User Manual Parameters The polar motion xy corrections in arcseconds Limits 1 to 1 arcsec Keywords None Examples POLE 0 10 0 23 Comments This command overrides the initial values for polar motion which are derived from an interpolation formula supplied by the International Earth Rotation and Reference Systems Service It makes a very small difference to the pointing of the telescope and is too esoteric for normal use 4 48 POSITION Move the telescope by a previously stored y or Aa A0 offset Format POSITION lt position_number gt Defaults None POSITION 0 zero offset is automatically selected on startup or change of source Parameters The position number is an integer in the range 0 to 20 The offset values for a given position number must have been set up using the ENTER or STORE command
3. 6 3 Encoder display The second page displays the encoder readings for altitude azimuth and all of the instrument rotators In addition the positions of the dome focus and primary mirror cover are shown The layout is shown in Figure 3 E TCS DISPLAY File Edit Commands Options Print Azimuth Absolute Cassegrain Absolute Azimuth Gear i Cass Incremental Azimuth Roller Azimuth Tape 1 t Prime Focus Absolute Azimuth Tape 2 Prime Incremental Azimuth Tape 3 Azimuth Tape 4 GRACE Absolute GRACE Incremental Elevation Absolute Elevation Gear i GHRIL Absolute Elevation Roller i GHRIL Incremental Dome Absolute Focus Absolute Mirror Cover ADC Autoguider packet Figure 3 The encoder display screen In case of pointing difficulties it is particularly useful to compare the individual encoders on the same axis The values displayed are as follows e Azimuth units are degrees minutes seconds The encoder combination used for tracking can be changed using the ENCODER and RATE commands o Absolute broken 52 WHIT TCS 9 issue 3 3 WHT TCS User Manual o Incremental gear o Incremental roller not currently in use o Incremental inductive tape encoder There are 4 reading heads AZ TAPE1 to AZ TAPE4 not currently in use e Elevation units are degrees minutes seconds o Absolute o Incremental gear o Incremental roller not currently in use e For each rotator Cassegrain Prime foc
4. Format SAVETCS filename Defaults The defaults for the filename are File SAVED CON Directory device CONIG DIR Extension CON Keywords None Parameters The path for the configuration file Examples SAVETCS SAVETCS SAVED CON SAVETCS MYCONFIG Comments The configuration can be saved in the default configuration area on the TCS computer whence it may be recovered on a subsequent night with the SETTCS command Old configurations will be deleted periodically The CON extension is mandatory any other extension will be removed and CON substituted On TCSEXIT the configuration is saved as SAVED CON This is equivalent to issuing the command SAVETCS 4 61 SETTCS Restore the TCS configuration from disk file Format SETTCS filename Defaults The defaults for the filename are File SAVED CON Directory device CONIG DIR Extension CON Keywords None Parameters The path for the configuration file Examples SETTCS SETTCS SAVED CON 1 SETTCS MYCONFIG Comments The configuration includes the STATION INSTRUMENT and AGSELECT values as well as defined aperture offsets including the nominal aperture offset After the configuration is restored no aperture is selected this is equivalent to issuing the command APERTURE 0 The final step of the command performs the equivalent of a CALIBRATE LAST and the user is asked to confirm acceptance of the calibrate results The SETTCS command should be used while the telescope is stopped
5. 100 to 100 s s in RA and 100 to 100 arcsec s in declination DIFF RATES 0 01 0 3 The differential non sidereal tracking rates are added to the edit source block They must be actioned using the NEXT command Note that differential rates are not included in a catalogue entry 4 17 DISPLAY Change the coordinate system of the information display Format Defaults Parameters Keywords Examples Comments DISPLAY lt coordinate system gt None The default coordinate system on startup is INPUT None The allowed coordinate systems are INPUT a and in the system used to input the source position APPARENT a and in geocentric apparent coordinates J2000 a and in J2000 mean coordinates B1950 a and in B1950 mean coordinates HA DEC Topocentric hour angle and declination DISPLAY J2000 For technical reasons there are restrictions on the permitted combinations of input and display coordinates as follows INPUT always allowed 40 WHT TCS 9 issue 3 3 WHT TCS User Manual APPARENT always allowed J2000 not allowed for input in apparent coordinates B1950 not allowed for input in apparent or FK5 J coordinates HA DEC always allowed 4 18 DOME Move the dome to the specified azimuth and stop Format DOME lt angle gt Defaults None Parameters The angle in degrees Limits The angle must be in the range 0 to 360 even though the dome has no mechanical limits
6. AUTOGUIDE lt state gt lt x gt lt y gt WAIT Defaults None Parameters The optional parameters x and y are the desired pixel coordinates for the guide star and are used with the ON keyword If they are not specified the system will adopt the most recent autoguider coordinates sent to the TCS WAIT is designed for use when the AUTOGUIDE command is sent via DRAMA The command will not complete until the guidestar is in position The in position limit can be changed with the AGLIMIT command Keywords Valid autoguider states are 15 WHT TCS 9 issue 3 3 WHT TCS User Manual Examples Comments ON specifying that the telescope should be guided in response to guiding errors from the CCD autoguider OFF specifying that autoguiding should be switched off i e that any guiding errors from the CCD autoguider should be ignored SUSPEND put the TCS in a state where pixel coordinates are read from the autoguider and the current reference position is maintained but guiding errors are not applied RESUME Restart guiding if the loop has been suspended AUTOGUIDE ON AUTOGUIDE ON 122 5 63 5 The autoguider sends xy pixel coordinates of a guide star to the telescope control computer The TCS then adjusts the telescope drives to keep the star at a given location on the autoguider CCD If the intention is to maintain the current positioning of a field e g if acquisition onto a spectrograph slit has been veri
7. Defaults None The startup value is 0 4 um Parameters The wavelength in microns Limits 0 3 to 35 um Keywords None Examples WAVELENGTH 0 55 4 81 WRAP Override the azimuth wrap value i e the multiple of 360 which must be added to the raw encoder reading to give the correct azimuth Format WRAP lt wrap_ value gt Defaults None Parameters The wrap value in multiples of one revolution The allowed values are 0 and 1 Keywords None Examples WRAP 1 Comments This command was only of use when there was a working azimuth absolute encoder It should not be used now 4 82 ZEROSET Set the zero points of incremental encoders by a variety of methods Format ZEROSET lt mechanism gt lt method gt lt position gt Defaults None Keywords lt mechanism gt The following mechanisms may be zeroset AZIMUTH ALTITUDE ROTATOR 43 WHT TCS 9 issue 3 3 Parameters Examples Comments WHT TCS User Manual lt method gt Several different methods are provided to set the zero points of the incremental encoders in order to reduce the dependence on individual bits of electronics These are TARGET CANC ABSOLUTI TO ma Ea GI PARK This method is in principle capable of the highest accuracy A mechanical target is used to provide a fixed reference point The targets are located at azimuth 298 35 a
8. ENCODER ON AZIMUTH GEAR and ENCODER ON ALTITUDE GEAR The TCS starts in this state by default 20 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 21 ENGINEERING Put the telescope into engineering mode Format ENGINEERING Defaults None Parameters None Keywords None Comments This command should be used as part of the normal shutdown procedure at the end of the night to return to engineering mode at any time or in an emergency to remove power from the drives and put on the brakes It is equivalent to turning the COMP ENG key on the engineering desk to the ENG position To return to computer mode turn the key to the COMP position and press the COMP ENG button next to it on the desk 4 22 ENTER Set up aperture and positional offsets for repeated use Format ENTER APERTURE lt aperture number gt lt x offset gt lt y offset gt ENTER ARC POSITION lt pos_number gt lt xi gt lt eta gt ENTER TIME POSITION lt pos number gt lt ra_offset gt lt dec_offset gt Defaults None Parameters lt aperture number gt is an integer in the range 0 to 20 0 being the reference position the default on source change lt pos_number gt is an integer in the range 0 to 20 Position 0 is the nominal offset and can only be used with tangent plane offsets ENTER ARC
9. WHT TCS 9 issue 3 3 WHT TCS User Manual 2 STARTING AND STOPPING THE TCS 2 1 Startup To start the TCS log in to LPAS4 either from the X terminal in the WHT control desk or from a terminal window on the Instrument Control computer The username and password are displayed on the X terminal If the TCS is not running you will be presented with a START menu similar to This is the WHT TELESCOPE CONTROL SYSTEM The TCS is not running Please enter an option START Start the TCS version W27 1 0 Info display on 161 72 6 109 USER window on 61 72 6 4109 SIMULATE Run the TCS version W27 1 0 in simulation mode Info display on lpas4 USER window on Ilpas4 VERSION Select a different TCS version DISPLAY Select different display devices EXIT Exit this menu and log out Option gt START runs the displayed TCS version The login window disappears then the Display and User windows appear The User window displays a few lines of information followed by the USER gt prompt VERSION allows the user to choose a different version of the TCS A list of the available versions is displayed enter the version required or press RETURN to keep the default value DISPLAY is used to select a different device for the Display and User windows Enter the IP name or address of the new device for the Display window and again for the User win
10. 80 minutes for continuous logging or 30 minutes for saved encoder data Keywords lt system gt valid keywords are AUTOGUIDER pixel coordinates produced by one of the CCD autoguiders ENCODERS encoder readings servo errors and drive demands for the telescope axes current rotator and auxiliary mechanisms TV pixel coordinates produced by the acquisition TV system s GUIDE or I GUIDE functions lt state gt valid keywords are ON turn logging on OFF turn logging off and display the filename KEEP only used with the ENCODERS keyword This will save the previous lt duration gt minutes of encoder data to a log file Examples LOG AUTO ON 15 LOG ENC ON 5 LOG ENC KEEP 10 Comments If TV or autoguider logging is turned on when it is already enabled the log file is closed and a new one is opened If encoder logging is turned on when it is already enabled the log will continue to be written to the current file if the new duration is equal to or greater than the previous duration otherwise the file will be closed A LOG ENC KEEP command can only save data starting from the last time a LOG ENC KEEP command was issued or for the last 30 minutes whichever is the shorter time Any of the logging functions may be run simultaneously 4 37 MARK Store the current position of the telescope as a named catalogue entry Format Defaults Parameters Keywords Examples Comments MARK lt source name gt None The name of the sourc
11. Keywords None Examples DOME 275 34 4 19 ELEVATION Synonym for ALTITUDE q v 4 20 ENCODER Set the combination of incremental encoders used for tracking Format ENCODER lt state gt lt mechanism gt lt encoder_ name gt Defaults None The gear encoders are selected on startup Keywords Valid states are ON add an encoder to the tracking combination OFF remove an encoder from the tracking combination Valid mechanism encoder name combinations are ALTITUDE GEAR altitude gear encoder ALTITUDE ROLL altitude friction driven roller encoder not in use AZIMUTH GEAR azimuth gear encoder AZIMUTH ROLL azimuth friction driven roller encoder not in use Examples ENCODER ON AZIMUTH GEAR Comments There are three independent incremental encoding systems on the WHT azimuth axis any of which may be used for pointing and tracking These are a gear encoder coupled to the telescope via the main drive gear an inductive tape encoder with four reading heads and a friction driven roller encoder The roller encoder is not recommended as it slips The gear default is the best for normal use The tape encoders were used for test purposes and are not currently connected The command will be rejected if an ENCODER OFF command removes the last enabled encoder for that mechanism Since now only the GEAR encoders are suitable for tracking the only commands that work are
12. TV Cassegrain guiding using UltraDAS acquisition camera TV PRIME the prime focus off axis autoguider AF2 TV Autofib2 using acquisition camera TV bundles AF2 FIXED the fixed probe of the Autofib2 fibre positioner AF2 MOVING the moving probe of the Autofib2 fibre positioner WHIRCAM autoguider used with a beamsplitter at GHRIL INTEGRAL Integral s autoguider STJ STJ autoguider GHRIL reflected configuration NAOMI NAOMI fast steering mirror driven configuration GRACE used at GRACE for tests set up like WHIRCAM EXPO guide signal is generated from EXPO s science camera Examples AGSELECT CASS Comments The TCS needs to know which autoguider is currently in use in order to perform the conversion between guide star pixel position and drive corrections 4 5 AGVIEW Perform an aperture offset to move an image onto the autoguider CCD Format AGVIEW Defaults None 14 WHT TCS 9 issue 3 3 WHT TCS User Manual Parameters None Keywords None Comments This command allows a field to be viewed using the autoguider An offset is applied to move the image from the nominal aperture usually the rotator centre to the centre of the autoguider field It is essential to tell the TCS which autoguider is in use and to define its position in the focal plane use the AGSELECT and PROBE commands as necessary 4 6 ALTITUDE Move to the specified altitude and stop Format ALTITUDE lt an
13. Windshield power OFF Windshield overtravel SET Windshield torque trip TRIPPED Windshield PARKED Platform pin IN Shutter and windshield CLOSED Dome interlock DISABLED Cassegrain focus SELECTED Prime focus GRACE Nasmyth focus GHRIL Nasmyth focus Folded Cass focus Primary mirror cover CLOSED Primary mirror cover NOT OPEN Nasmyth flat STOWED Sec mirror cover OFF Azimuth zone YELLOW Access park tie OUT AP 3 access platform STOWED Revolving floor latch CLEAR Figure 7 The dome status and manual overrides screen e Engineering overrides These cause computer control for individual mechanisms to be disabled and are controlled by latching buttons on the engineering desk Overrides are on when the buttons are latched down The yellow lamps will be lit when the mechanisms concerned are under engineering control either because the system as a whole is in engineering mode or as a result of overrides The display shows ENABLED when the mechanism is overridden DISABLED otherwise Mechanisms which may be overridden and their states in normal computer controlled operation are o Dome normally DISABLED o Focus normally DISABLED note that the focus drive does not work under override o Shutters normally DISABLED o Mirror cover normally ENABLED e Control locations These show the state of the remote local off keyswitches on the gallery control panel REMOTE means that the mechanism can be driven from the control room LOCAL that it
14. aperture offset e BEAMSWITCH Execute an aperture offset with direct input of x and y e ENTER Input data for numbered aperture or positional offsets e OFFSET Execute a positional offset with direct input of Aa Ad or amp y e POSITION Execute a preset numbered positional 7 or A Ao offset e SLOWOFF Execute a positional offset at a given rate with direct input of 7 and rate e STORE Store aperture or positional offsets set up using the handset e TWEAK Apply a given x4 v4 pa aperture offset 3 6 Autoguiding AGSELECT and PROBE are allowed in engineering mode AGVIEW and AUTOGUIDE are not e AGLIMIT Set the limit determining whether the guidestar is in position e AGSELECT Identify the autoguider currently in use e AGVIEW Aperture offset to move image to autoguider field e AUTOGUIDE Lock or unlock the autoguider loop e PROBE Input coordinates of guide probe e TVCAMERA Identify the TV camera currently in use e TVGUIDE Lock or unlock the TV guiding loop 3 7 Calibration procedures The keywords for this command which require the telescope to be moved are not allowed in engineering mode e CALIBRATE Determine encoder zero points and collimation errors 3 8 Mechanism control None allowed in engineering mode e ALTITUDE Move the telescope to a given altitude and stop it e AZIMUTH Move the telescope to a given azimuth and stop it e DFOCUS Change
15. as the telescope moves MOUNT This keyword specifies that the parameter gives a mount position angle i e measured with respect to a fiducial mark fixed to the mirror cell ROTATOR MOUNT stops the turntable at the requested position angle it makes no sense to track a mount position angle FLOAT This option is designed to minimise unnecessary rotation in the case where the precise value of the sky position angle is unimportant On source change the rotator is set to a sky position angle corresponding to its current mount value Thereafter it rotates as for the SKY keyword VERTICAL This keyword sets the reference axis in the instrument to the vertical direction and stops the rotator tracking It is intended to minimise loss of light due to differential refraction during spectroscopic observing Note that autoguiding is not possible since off axis images move in the focal plane VFLOAT This keyword sets the slit to the vertical direction on source change and then tracks at a constant sky position angle It is therefore equivalent to typing ROT SKY lt parallactic_angle gt This is generally more useful than the VERTICAL option since autoguiding is possible ROTATOR SKY 275 34 33 WHT TCS 9 issue 3 3 4 59 RV WHT TCS User Manual ROTATOR MOUNT 28 0 ROTATOR FLOAT Synonym for RADIAL VELOCITY q v 4 60 SAVETCS Save the current TCS configuration to disk file
16. causes the entire command buffer to be listed Defaults Last command Examples RECALL 2 RECALL SOURCE RECALL ALL Comments This command is essentially identical to its namesake in DCL RECALL lt n gt recalls the nth last command within a 50 line buffer and RECALL string recalls the last command beginning with string RECALL ALL lists the command buffer If no argument is given the last command is recalled but this is more conveniently done with the cursor key 4 56 REMOVE Remove the entry for the named source from the user catalogue Format REMOVE lt source_ name gt Defaults None Parameters The name of the source to be deleted The name may be a string of up to 20 characters extra characters are lost To include spaces the whole string should be enclosed within double quotes Keywords None Examples REMOVE NGC 4151 REMOVE Supe rnova in LMC 4 57 RMS Turn calculation of mean and rms servo or guiding errors on or off and display the results Format Defaults Keywords RMS lt error gt lt state gt None error gt is the source of errors lt SERVO Main drive position errors a WHT TCS 9 issue 3 3 WHT TCS User Manual Examples Comments AUTOGUIDER Autoguider guiding errors TV TV system guide errors not normally connected for the INT lt state gt is either ON Begin calculation of errors OFF End calculation of errors and display results RMS SERVO ON This command
17. cover is only used when the mirror is not on the telescope e Azimuth zone This gives the position of the switch that is read on startup to resolve the ambiguity in the azimuth absolute encoder RED 180 lt azimuth lt 120 and YELLOW 120 lt azimuth lt 360 approximately e Access park tie This is inserted to stop the telescope moving when it is out of balance e g when the mirror cell has been removed or during an end change and force engineering mode Normal state OUT alarm state IN e Revolving floor latch This stops the telescope moving in azimuth when it is at the correct position for the mirror to be removed i e with the fixed and moving parts of the mirror trolley rails lined up Normal state CLEAR alarm state SET e AP 3 access platform This stops the telescope being driven in azimuth when the barrier is removed to give access to the top end ring Normal state STOWED alarm state DEPLOYED 58 WHT TCS 9 issue 3 3 WHT TCS User Manual 7 CATALOGUES 7 1 Catalogue format Object catalogues may be created using the TCS ADD and OUTPUT commands or may be imported from the instrumentation computer using INCLUDE Catalogues are simply lists of source parameters in free format with spaces separating the fields All data for an entry should be on one line of the file Anything following an asterisk or an exclamation mark is treated as a comment and is ignored by the TCS Do not use tab control
18. is used in conjunction with the STORE POSITION command to set up positional offsets which may be recalled with the POSITION command To define an offset move an object to the start position using one of X_Y RA DEC or ALT AZ Then switch to OFFSET mode move the object to the end position exit from the handset and store the offset with STORE POSITION lt position_number gt where lt position_number gt is in the range 0 to 20 POSITION lt position_number gt recalls the offset which is defined in the tangent plane POSITION 0 is the nominal offset and is reset on source change 5 2 5 APOFF mode This mode changes the aperture offset interactively It is intended to be used to shift an object to an instrument aperture away from the reference position The aperture coordinates may be recorded for future use with the command STORE APERTURE The image moves in x and y on the TV and or detector To set up a new aperture move an object to the reference position using X_Y RA_DEC or ALT_AZ mode switch to APOFF move it to the new aperture spectrograph slit or whatever exit from the handset and type STORE APERTURE lt aperture_number gt where lt aperture number gt is in the range 0 to 20 STORE APERTURE 0 redefines the reference position The APOFF mode may be used even when the autoguider loop is locked This is useful for making small corrections e g to optimise a target position on the spectrogr
19. must be driven from the balcony panels o Windshield normally LOCAL e Power Normally ON alarm state OFF o Dome o Shutter o Windshield e Overtravel alarms Normally CLEAR alarm state SET o Shutter WHT TCS 9 issue 3 3 WHT TCS User Manual o Windshield e Torque trip alarms Shut down the drive until reset on the gallery control panel Normally CLEAR alarm state TRIPPED o Shutter o Windshield e Windshield parked indicator PARKED or NOT PARKED e Shutter and windshield OPEN CLOSED e Platform pin If IN this disables dome rotation Normally OUT e Dome interlock Normally DISABLED alarm state ENABLED e Focal station in use displays SELECTED o Cassegrain secondary mirror on Nasmyth flat stowed o Prime prime focus unit on o GHRIL Nasmyth focus secondary mirror on Nasmyth flat in GHRIL position o GRACE Nasmyth focus secondary mirror on Nasmyth flat in GRACE position o Folded Cassegrain secondary mirror on Nasmyth flat in folded Cassegrain position used for WYFFOS calibration unit e Primary mirror cover o CLOSED NOT CLOSED Reads CLOSED when the cover is fully shut NOT CLOSED otherwise o OPEN NOT OPEN Reads OPEN when the cover is fully open NOT OPEN otherwise e Nasmyth flat STOWED is the appropriate position for Cassegrain and prime foci NOT STOWED for Nasmyth and folded Cassegrain The flat should always be STOWED when not in use e Secondary mirror cover Always OFF since the
20. offset currently enabled blank if zero If the POSITION command was used then the offset number 1 to 20 is given in the first field this is left blank if the OFFSET command was used instead The next two fields give the offset components in the RA and Dec directions For an offset specified in tangent plane coodinates by ENTER ARC the values are labelled XI and ETA and given in arcseconds For an incremental offset ENTER TIME they are given in seconds of time and seconds of arc respectively and are called RA and DEC For a tangent plane offset the origin of the offset will be displayed after the offset components if a nominal offset had been set up using POSITION 0 The total offset applied to the target position is the sum of the offset and the offset origin Aperture offset currently enabled blank if zero If the APERTURE command was used then the first field gives the aperture number 1 to 20 if BEAMSWITCH was used instead then the field is left blank The next two fields give the x4 and y4 components of the offset in arcsec Reference position alias aperture 0 offset from the rotator centre in x4 and y4 arcsec Topocentric azimuth and elevation of the target not the telescope e Telescope state The possible messages are O O O ENG MODE the system is in engineering mode STOPPED the telescope drives are stopped MOVING the telescope is in motion but has n
21. or in engineering mode It s intended to allow the configuration to be restored after the TCS has been restarted perhaps because of engineering work during the day 34 WHT TCS 9 issue 3 3 WHT TCS User Manual On TCSEXIT the configuration is saved as SAVED CON One can restore this with command SETTCS If there is need to restore a prior configuration use a generation number e g S before last 4 62 SENSOR ETTCS SAVED CON 1 for the configuration of the TCS session Enable or disable tracking corrections derived from displacement transducers Format SENSOR lt sensor_ type gt lt state gt Defaults None Parameters None Keywords lt sensor_type gt This selects the sensors whose tracking corrections are to be en disabled SECONDARY HORIZONTAL lt state gt ON OFF The three displacement transducers which are used to measure the tilt of the secondary mirror The two transducers which measure the horizontal movement of the telescope These are used to provide tracking corrections in Azimuth for the gear incremental encoder but are not relevant if the tape encoder is used see ENCODER q v enables corrections disables corrections Examples SENSOR HORIZ OFF 4 63 SHOW Display data on the topic indicated by the keyword This command is not allowed from DRAMA or ICL Format SHOW lt show topic gt Defaults None Parameters N
22. the focus by a specified amount e DOME Move the dome to a given azimuth and stop it e FOCUS Move the focus to a specified position e PARK Move the telescope to a defined position 5 ky P gt WHT TCS 9 issue 3 3 WHT TCS User Manual e STOP Stop a mechanism or combination of mechanisms e UNWRAP Move azimuth or rotator by 360 3 9 Mechanism configuration ENCODER and ZEROSET are allowed in engineering mode TRACK is not e ENCODER Set the combination of encoders used for pointing e ENGINEERING Select engineering mode e RATE Set the encoder used by the hardware position loop e SENSOR En disable corrections from displacement transducers e TCORRECTION En disable focus corrections for temperature e TRACK Turn focus dome rotator or telescope tracking on or off e WRAP DISABLED Override the azimuth wrap determined from the zone switch e ZEROSET Determine incremental encoder zero points 3 10 Change of focal station and instrument Both allowed in engineering mode e STATION Select focal station and rotator e INSTRUMENT Tell the TCS which instrument is in use 3 11 Display functions All allowed in engineering mode MOON and SHOW are not allowed from DRAMA or ICL e DISPLAY Change the coordinate system of the displayed telescope position e MOON Give the current right ascension and declination of the Moon e PAGE Switch to another inform
23. then be asked whether all of the stars were centred correctly If you do not answer Y to this question then the procedure will be aborted The derived and previous values will be displayed together with their r m s errors and you will be asked whether the solution is reasonable The errors should be in the range 0 5 to 1 0 arcsec for IE 1 0 to 2 0 arcsec for CA and 1 0 to 3 0 arcsec for IA If the errors are much larger than these values then the solution should be rejected Unless there has been a major change of configuration the coefficients should not alter by more than a few arcseconds from night to night Gross differences may indicate a problem CTRL Z may be used to abort the procedure at any time but all of the measurements will be lost ry a F h 4 13 CLONE Create delete a copy of the DISPLAY screen Format Defaults Parameters Keywords Examples Comments 4 14 DEC CLONE lt state gt lt device gt None The name or IP address of the display device The allowed states are ON creates a copy of the display screen on the specified device OFF deletes all copies of the display screen from the specified device CLONE ON 1lpx31 CLONE OFF 161 72 6 108 If a window created by CLONE is closed other than by the CLONE OFF command e g by using the window buttons the command CLONE OFF device must be issued to clear internal variables Enter a declination in the edit s
24. when using DRAMA is identical to the local interface but the complete command must be issued Prompts for unspecified input are issued on the local interface not on the DRAMA interface and if the prompted for input is not given on the local interface the DRAMA command will hang until it times out The main differences between the local interface and the DRAMA interface are 1 DRAMA will always acknowledge completion of a command Response will be almost instantaneous except for commands which move the telescope mechanisms These complete when the mechanisms concerned are in position 2 There is no prompting on the DRAMA interface 3 Error messages differ usually in the sense that the TCS gives an additional more accurate description of the problem 4 DRAMA does not allow a command to be issued if a previous attempt at the same action is still in progress The TCS local interface allows the first command to be overridden by the second This can sometimes lead to problems e g if the wrong object is selected 5 A few commands primarily those which produce screen output are not available from DRAMA These are noted explicitly below 4 1 ACKNOWLEDGE Turn off the engineering mode dome position and or software limit alarms Format ACKNOWLEDGE lt alarm_type gt Defaults ACKNOWLEDGE ALL Parameters None Keywords LIMIT turn off an alarm caused by a main drive software limit ENGINEERING
25. 023 4 44 PARK Move the telescope to a defined park position and stop it 28 WHT TCS 9 issue 3 3 WHT TCS User Manual Format PARK lt park position gt Defaults None Keywords The valid park positions are ZENITH The zenith park position azimuth 298 64 altitude 90 28 AP1 Access Park 1 azimuth 298 64 altitude 19 62 Examples PARK ZEN Comments The telescope will not move unless both its axes have been zeroset 4 45 PM Synonym for PROPER MOTION q v 4 46 POINT Log in TPOINT format the present position of the telescope as read on the encoders Format POINT lt file status gt Defaults POINT OLD Parameters None Keywords NEW opens a new set of log files in the POINTING directory and logs the telescope position CALIBRATE opens a new set of log files in the CALIBRATE directory and logs the telescope position OLD appends to the latest set of log files unless none exist in which case a new set of pointing files are opened in the POINTING directory Examples POINT POINT NEW Comments The data are logged to pointing data files in a format suitable for input to the TPOINT analysis package The following pointing files are created in WHT DATA POINTING TRACKyymmdd DAT the encoder combination used for telescope tracking usually azimuth and altitude gear encoders DEMANDyymmdd DAT the demand position calculated by the TCS Used for internal consistency tests only
26. CLEAR Altitude ve prelimit CLEAR Altitude limit CLEAR Altitude ve prelimit CLEAR Altitude limit CLEAR Altitude final limit CLEAR Prime focus TT ve limit SET Prime focus TT ve limit SET Cassegrain TT ve limit CLEAR Cassegrain TT ve limit CLEAR Cass wrap e limit CLEAR Cass wrap vye limit CLEAR GRACE TT ve limit CLEAR GRACE TT ve limit CLEAR GHRIL TT ve limit CLEAR GHRIL TT ve limit CLEAR Focus ve limit CLEAR Focus e limit CLEAR WHT TCS 9 issue 3 3 WHT TCS User Manual Emergency stop This shows the state of the red emergency stop buttons ACTUATED or RELEASED None of the drives will function unless all the buttons are out in which case the display shows RELEASED Telescope power Should be ON Computer reset button This is the button on the engineering desk which is pressed to switch from engineering to computer mode It is ENABLED lamp on when switch over is allowed DISABLED if not Mode selected COMPUTER or ENGINEER duplicated on the top level display Azimuth limits These are hardware limits and should not be encountered in normal computer controlled operation The pre limits are hit first and cause the system to revert to engineering mode The telescope can only be driven out of a main limit by hand The display should show CLEAR for all limits and pre limits in normal operation and SET with the message in reverse video if the limit has been hit The nominal hardwar
27. D Cassegrain auxiliary port CCD camera ULTRACAM UltraCAM private instrument INGRID INGRID NAOMI NAOMI in GRACE LIRIS Long slit intermediate resolution infrared spectrograph INTEGRAL Integral field unit private instrument PFCCD Prime focus imaging CCD camera AUTOFIB Prime focus automatic fibre positioner SCAM S CAM private instrument EXPO Extreme Polarimeter private instrument ACAM Cassegrain Auxiliary Port Camera OWN Spare for users own instrument 25 WHT TCS 9 issue 3 3 WHT TCS User Manual Examples Comments 4 36 LOG Log encoders packet INSTRUMENT ISIS This command sets the origin of position angle used for a specific instrument and the scale and orientation for the TWEAK command q v Position angle on the sky is normally defined to be along the slit in a spectrograph and aligned with one of the detector axes for an imaging instrument The scale and orientation parameters are currently set to match the standard TCS xy coordinate system tracking errors and associated data every cycle log autoguider data on receipt of Format LOG lt system gt lt state gt lt duration gt Defaults The duration parameter defaults to 15 minutes if omitted it will be prompted for The user can accept the default or can enter a new duration Parameters The required duration of the log in minutes the maximum duration is
28. ET Oil pump alarm Normal state CLEAR alarm state TRIPPED Altitude and azimuth oil filter alarms Normal state CLEAR alarm state SET Oil temperature Should read NORMAL alarm state HIGH Oil level Should read NORMAL alarm state LOW Altitude and azimuth oil flow divider alarms Normal state CLEAR alarm state SET e Power O O Mains alarm Normal state CLEAR alarm state SET Power amplifier Normal state WORKING alarm state FAULTY e Primary mirror support O O Nitrogen pressure Normal state NORMAL alarm state LOW A failure here generally means that the nitrogen supply has run out Mirror height Normal state NORMAL e Nasmyth gate alarm This is triggered if one of the Nasmyth access gates on the balcony is open but there is no Nasmyth platform next to it It causes a switch to engineering mode Normal state NOT OPEN 56 WHT TCS 9 issue 3 3 WHT TCS User Manual e Dome emergency stop Normal state CLEAR 6 7 Dome status and manual overrides page This page contains the engineering override indicators for individual mechanisms and the status bits concerning dome and shutters The layout is shown in Figure 7 Do a OX File Edit Commands Options Print Dome manual override DISABLED Shutters manual override DISABLED Focus manual override DISABLED Mirror cover man override ENABLED Dome power OFF Shutter power OFF Shutter overtravel CLEAR Shutter torque trip CLEAR Windshield control REMOTE
29. K5 system B lt year gt Mean coordinates FK4 system Keywords None Limits The year must be in the range 1800 0 to 2100 0 Examples EQUINOX B1950 EQUINOX J1992 5 EQUINOX APP 4 25 ERASE Erase all entries from the current user catalogue Format ERASE Defaults None Parameters None Keywords None 4 26 FIND Retrieve data for the named source from the user or system catalogues see Catalogues and place them in the edit source block Format FIND lt source_name gt Defaults None Parameters The name of the the source to be retrieved It can be a string of up to 20 characters extra characters are lost To include spaces the whole string should be enclosed within double quotes Keywords None Examples FIND HD123456 FIND NGC_4151 FIND Supernova in LMC Comments The user catalogue is searched first followed by the system catalogue 4 27 FOCUS Drive the focus to a specified setting and stop it Format FOCUS lt setting gt Defaults None Parameters The focus in mm Limits 34 5 to 129 0 mm 297 WHT TCS 9 issue 3 3 WHT TCS User Manual Keywords None Examples FOCUS 50 5 Comments The focus is normally adjusted to compensate for changes in tube temperature and elevation at Cassegrain The input to FOCUS is a virtual position which should be independent of these corrections It should not therefore vary from night to night Use the DFOCUS command to compensate for know
30. NE DEC DFOCUS DIFF_RATES DISPLAY DOME ELEVATION ENCODER ENGINEERING ENTER EPOCH EQUINOX ERASE FIND FOCUS GOCAT GOMOON GOTO HANDSET HELP WHT TCS User Manual 14 14 15 15 15 16 16 16 17 18 18 19 19 19 20 20 20 21 21 21 22 22 22 22 23 23 23 24 24 WHT TCS 9 issue 3 3 4 33 4 34 4 35 4 36 4 37 4 38 4 39 4 40 4 41 4 42 4 43 4 44 4 45 4 46 4 47 4 48 4 49 4 50 4 51 4 52 4 53 4 54 4 55 4 56 4 57 4 58 4 59 4 60 4 61 HUMIDITY INCLUDE INSTRUMENT LOG MARK MOON NEXT OFFSET OUTPUT PAGE PARALLAX PARK PM POINT POLE POSITION PRESSURE PROBE PROPER MOTION RA RADIAL VEL RATE RECALL REMOVE RMS ROTATOR RV SAVETCS SETTCS WHT TCS User Manual 25 25 25 26 26 27 27 27 27 28 28 28 29 29 29 30 30 30 31 31 31 31 32 32 32 33 34 34 34 WHT TCS 9 issue 3 3 4 62 4 63 4 64 4 65 4 66 4 67 4 68 4 69 4 70 4 71 4 72 4 73 4 74 4 75 4 76 4 77 4 78 4 79 4 80 4 81 4 82 5 5 1 5 2 5 3 6 6 1 6 2 SENSOR SHOW SLOWOFF SNAPSHOT SOURCE STATION STOP STORE TCSEXIT TEMPERATURE TCORRECTION TRACK TRANSFER TVCAMERA TVGUIDE TWEAK UNWRAP UT1UTC WAVELENGTH WRAP ZEROSET THE TCS HANDSET General Handset m
31. OT GRACE ROT GRACE IRDEROT and GRACE _NOROT Options ending in DEROT indicate that the turntable is to be driven at a rate appropriate for the derotation optics rather than a directly mounted instrument Demand sky position angle as input using ROTATOR SKY and modified subsequently using the handset Blank if the rotator is not tracking e g fora ROTATOR MOUNT command Mount position angle a5 i WHT TCS 9 issue 3 3 WHT TCS User Manual o Mount error i e the error in mount position angle only displayed when the rotator is tracking Note that an error of 1 arcsecond corresponds to a displacement on the sky of 0 003 arcseconds at a typical maximum field radius of 10 arcminutes o Parallactic angle e Miscellaneous o Focus position mm This is a virtual focus position which should not depend on temperature elevation or the presence of filters in the beam It should in theory remain constant for a given focal station o The focus offset TC mm applied to compensate for expansion of the structure o The focus offset DF mm used to correct for additional optical elements e g filters in the beam o Dome azimuth The label flashes if the dome is out of position This will occur during a slew and briefly during tracking If the flashing is continuous and the dome is not moving to the correct azimuth then there is likely to be a fault in the dome drive most likely the TEM L system o Air mass relative to the zenith
32. Particle Physics and Astronomy Research Council Isaac Newton Group WHT TCS 9 William Herschel Telescope Telescope Control System USER MANUAL Robert Laing Marion Fisher Frank Gribbin Issue 3 3 23 July 2014 Isaac Newton Group Apartado 321 38780 S C La Palma Tenerife Canary Islands Telephone 34 922 425400 Fax 34 922 425401 Internet fjg ing iac es WHT TCS 9 issue 3 3 Table of Contents 1 INTRODUCTION 1 1 Purpose 1 2 Scope 1 3 Definitions 1 4 Overview 2 STARTING AND STOPPING THE TCS 2 1 Startup 2 2 Stopping the TCS 3 TCS COMMANDS SUMMARY 3 1 General TCS commands 3 2 Source data entry 3 3 Catalogue handling 3 4 Source change 3 5 Positional and Aperture offsets 3 6 Autoguiding 3 7 Calibration procedures 3 8 Mechanism control 3 9 Mechanism configuration 3 10 Change of focal station and instrument 3 11 Display functions 3 12 Logging of test data 3 13 Meteorological and Earth rotation data 4 TCS COMMAND LIST 41 ACKNOWLEDGE 4 2 ADD 4 3 AGLIMIT WHT TCS User Manual 10 10 10 10 11 11 11 11 11 12 12 12 12 12 13 13 14 14 WHT TCS 9 issue 3 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 4 12 4 13 4 14 4 15 4 16 4 17 4 18 4 19 4 20 4 21 4 22 4 23 4 24 4 25 4 26 4 27 4 28 4 29 4 30 4 31 4 32 AGSELECT AGVIEW ALTITUDE APERTURE AUTOGUIDE AZIMUTH BEAMSWITCH BLIND_OFFSET CALIBRATE CLO
33. SH_CASS This command is used to tell the TCS to use scale and orientation parameters for a particular TV camera These are needed when using the TVGUIDE command to autoguide or when logging test data 4 76 TVGUIDE Turn TV guiding off or turn it on with an optional xy position Format Defaults Parameters Keywords Examples Comments TVGUIDE lt state gt x y None The optional parameters x and y are the desired pixel coordinates for the guide star If they are not specified then the system will adopt the current position of the guide star Valid states are ON specifying that the telescope should be guided in response to guiding errors from the TV system in GUIDE or I GUIDE mode OFF specifying that TV guiding should be switched off i e that any guiding errors from the TV system should be ignored TVGUIDE ON TVGUIDE ON 122 5 63 2 When the TV system s GUIDE or I GUIDE function is selected xy pixel coordinates of a guide star are sent to the telescope control computer The TCS then adjusts the telescope drives to keep the star at a given location on the TV camera If the intention is to maintain the current positioning of a field e g if acquisition onto a spectrograph slit has been verified then the command TVGUIDE ON should be used This takes the first position received from the TV system after the command is issued and keeps the guide star there On the other hand if the TV coordin
34. UNWRAP will drive it to a position 360 away and stop it Finally if the mechanism is in the process of moving to a fixed position as a result of an AZIMUTH or ROTATOR MOUNT command for example then the demand position is altered by 360 if possible In all cases an error message is generated if the mechanism is on the unambiguous part of its range UNWRAP ROTATOR is not useful for the Nasmyth rotators which do not have limits enabled and is not allowed if they are in use sA WHT TCS 9 issue 3 3 WHT TCS User Manual 4 79 UT1UTC Enter the value of the correction to Universal Time UT1 UTC used in the control system Format UTLUTC lt correction gt Defaults None This command overrides the startup value of UT1 UTC which is determined from an interpolation formula supplied by the IERS Rapid Service Prediction Center Parameters The correction in seconds Limits l to 1s Keywords None Examples UT1UTC 0 0222 Comments The IERS bulletin is pinned up on a noticeboard in the control room it is also available on the TOs web pages or can be found on the Web at http maia usno navy mil ser7 ser7 dat The bulletin is updated weekly on Thursdays The predicted correction UT1 UTC for each night is listed in a table in the section headed PREDICTIONS 4 80 WAVELENGTH Enter the value of the effective wavelength of light used in the calculation of the refraction correction Format WAVELENGTH lt wavelength gt
35. YGRT O FFSET A POFF F OCUS R OTATOR USER gt HANDSET Figure 1 An example of the handset display showing the default on startup It shows the available increment values the accumulated increments and the modes Currently selected values are in reverse video Only the keys listed in the following table remain active Key Action lt or select next smaller increment gt or select next larger increment 2 or request input of increment value F8 select ALT AZ mode F9 select RA DEC mode F10 select X Y mode O oro select OFFSET mode Aora select APOFF mode Forf select FOCUS mode Rorr select ROTATOR mode 45 WHT TCS 9 issue 3 3 WHT TCS User Manual P requests the input of an increment value Enter the value in the appropriate units and then press RETURN Just press RETURN to escape from increment selection if you press the key by accident The F6 key is used to return to the USER gt prompt The default on first selecting the handset is the X_Y mode with an increment of 1 0 arcseconds Thereafter the accumulated increments in each mode and the currently selected mode and increment value are remembered on exit to USER gt level and restored when the handset is next used They are reset on source change using the GOTO GOCAT GOMOON NEXT or BLIND OFFSET commands 5 2 Handset modes There are seven handset modes each of which can be selected
36. _ POSITION lt x offset gt lt y offset gt lt xi gt lt eta gt and lt dec_offset gt are in arcseconds lt ra_offset gt is in seconds of time Keywords Valid offset modes are APERTURE set up an aperture offset in the focal plane ARC_POSITION set up a tangent plane offset n TIME POSITION setup an incremental offset a Examples ENTER APERTURE 3 1 5 20 3 ENTER ARC POSITION 3 3 0 12 0 ENTER TIME POSITION 1 0 33 11 Comments ENTER APERTURE sets up an aperture offset which can be applied using the APERTURE command ENTER ARC POSITION and ENTER TIME POSITION set up a positional offset which can be added to the telescope demand position using the POSITION command 4 23 EPOCH Enter a value for the epoch of the position into the edit source block Format EPOCH lt date gt Defaults None Parameters The epoch in years Keywords None Limits The year must be in the range 1800 0 to 2100 0 Examples EPOCH 1967 35 p pA WHT TCS 9 issue 3 3 WHT TCS User Manual Comments The epoch is used in conjunction with the proper motions to compute the position of date 4 24 EQUINOX Enter a value for the equinox of the position into the edit source block Format EQUINOX lt equinox gt Defaults None Parameters A code for the coordinate system followed for mean coordinates by the equinox in years The allowed systems are APPARENT Geocentric apparent coordinates J lt year gt Mean coordinates F
37. al plane aperture coordinate system is used with position angle measured anticlockwise 4 78 UNWRAP Rotate either the Azimuth axis or the current rotator by 360 from its current position if this is possible Format UNWRAP lt mechanism gt Defaults None Parameters None Keywords AZIMUTH The azimuth axis ROTATOR The currently selected rotator Example UNWRAP ROTATOR Comments The telescope will not move unless both its axes have been zeroset The azimuth axis and those rotators which have limits enabled Cassegrain and Prime foci have more than 360 of travel and part of their ranges are ambiguous The UNWRAP command is used to rotate these mechanisms by 360 in order to avoid tracking into a limit or to reset the mechanism if a limit has been hit during observing There are four possible modes of operation depending on the initial state Firstly if the mechanism is tracking normally and is in its ambiguous range then it is rotated by 360 and tracking is resumed This is useful if there is insufficient time to complete an observation before a limit is hit Secondly an azimuth or rotator software limit may be encountered whilst the telescope is tracking UNWRAP moves the mechanism to the correct position as on change of source and tracking is resumed this is always possible provided that the target is still above the horizon limit Thirdly if the mechanism in question is stopped in an ambiguous part of its travel
38. aph slit The telescope offset and the reference pixel coordinates on the autoguider are changed simultaneously in such a way that the guiding errors remain zero The image appears to move in the same way as in the X_Y mode Small increments lt 1 arcsec should be used in order to avoid losing the guide star 5 2 6 FOCUS mode Changes the telescope focus units are millimetres Always allow time for the focus to settle after an increment as the drive is a bit sticky It should eventually stop within 0 01 millimetres of the requested position 5 2 7 ROTATOR mode This increments the sky position angle of the rotator units are degrees It therefore only works when the rotator is tracking 5 3 Sign conventions For the modes which cause the image to move in the focal plane the sense of motion for the keys has been set so that the image moves in the obvious way The displayed cumulative totals for each mode refer to the motion of the telescope This coupled with the variety of different hand conventions of astronomical coordinate systems requires the sign conventions summarised below e ALT_AZ mode o lt Image moves left on the sky azimuth displayed o Image moves right on the sky azimuth displayed o f Image moves up on the sky altitude displayed o Image moves down on the sky altitude displayed e RA DEC mode o lt Image moves east right ascension displayed o Image moves west right ascension displ
39. ates are already known then the appropriate command is TVGUIDE ON x y This is likely to be useful when an observation is to be repeated and the field is to be positioned at the same place on the detector Note that for technical reasons connected with use of the command from ICL the command TVGUIDE ON 1 1 means the same as TVGUIDE ON The TCS must be told the camera in use see TVCAMERA otherwise the telescope corrections will be in the wrong direction 4 WHIT TCS 9 issue 3 3 WHT TCS User Manual 4 77 TWEAK Apply a given x4 v4 pa aperture offset to align a field on an instrument Format TWEAK lt x_offset gt lt y_offset gt lt rotation gt Defaults lt rotation gt defaults to 0 Parameters lt x_offset gt lt y_offset gt are displacements in x4 and y4 in arcsec lt rotation gt is the rotation of the field in degrees Keywords None Examples TWEAK 0 5 0 6 0 1 Comments This command is used to position a field precisely on an instrument It can be used whether or not the telescope is being autoguided and is useful for long slit spectroscopy especially when two objects are to be placed on the slit simultaneously It is not advisable to use displacements of more than arcsec or rotations of more than 0 1 when autoguiding since the guide star may be lost Larger offsets can be split into successive smaller ones or autoguiding may be suspended whilst the CCD window is moved The TCS foc
40. ation display page e SHOW Display information about the system state 3 12 Logging of test data All allowed in engineering mode e LOG Log encoders tracking errors and associated data e POINT Write encoder coordinates to a data file e RMS Calculate and display mean and rms servo errors e SNAPSHOT Record the current information display page 3 13 Meteorological and Earth rotation data All allowed in engineering mode e HUMIDITY Input relative humidity used in refraction calculation e POLE Input values of polar motion e PRESSURE Input barometric pressure used in refraction calculation e TEMPERATURE Input temperature used in refraction calculation e UTLUTC Input UT1 UTC e WAVELENGTH Input wavelength used in refraction calculation a bee WHT TCS 9 issue 3 3 WHT TCS User Manual 4 TCS COMMAND LIST The following section gives a brief description of the operation of each command together with examples and defaults It refers to the TCS local interface Notation e Examples of commands entered at the terminal are in typewriter font DEC 12 34 56 78 e Angle brackets denote parameter values or keywords lt angle gt e Square brackets denote optional parameter values or keywords x y all other parameters and keywords are obligatory In most cases TCS commands can be issued either at the local user interface terminal or using the DRAMA interface The command syntax
41. aults Parameters Keywords Examples Comments STOP lt mechanism gt STOP ALL None Valid mechanism names are ALL AZIMUTH ALTITUDE DOME FOCUS ROTATOR CASS PRIME GHRIL GRACE STOP ROT STOP The STOP ALL or STOP commands stop all mechanisms 38 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 69 STORE Store aperture and positional offsets Format Defaults Parameters Keywords Examples Comments STORE lt offset_type gt lt offset_number gt None lt offset_number gt is the aperture number if the APERTURE keyword is specified see below It must be an integer in the range 0 to 20 APERTURE 0 is the reference position and is not reset on source change lt offset_number gt is the position number if the POSITION keyword is specified see below It must be an integer in the range 0 to 20 POSITION 0 is the nominal offset and is reset on source change Valid offset types are POSITION sets up a n or Aq AO positional offset which can be applied using the POSITION command APERTURE sets up a beamswitch position which can be applied to the telescope using the APERTURE command STORE APERTURE 3 The command may be used to store positional or aperture offsets which have been found using the APOFF or OFFSET handset modes or input using the BEAMSWITCH OFFSET or SLOWOFF commands They may then be recalled for future
42. ayed o ft Image moves north declination displayed o Image moves south declination displayed _47 WHT TCS 9 issue 3 3 WHT TCS User Manual e X_Y mode The sign convention has been used to be consistent with that used for apertures set up with the BEAMSWITCH and ENTER APERTURE commands o lt Image moves left on TV x displayed o Image moves right on TV x displayed o ft Image moves up on TV y displayed o Image moves down on TV y displayed e OFFSET mode As for X_Y e APOFF mode As for X_Y e FOCUS mode o lt Focus o Focus e ROTATOR mode o Sky position angle o Sky position angle If the image appears to move in a direction opposite to that expected check that the TV scan switches are in their correct positions for the optical configuration in use 48 WHT TCS 9 issue 3 3 WHT TCS User Manual 6 THE TCS DISPLAY 6 1 General The display has six screens arranged as follows e Source and telescope information appears on startup e Encoder values e Temperature sensors and transducer readings e Limit computer mode and emergency stop indicators e Alarm indicators e Manual overrides dome and mirror cover status access park interlocks and focal station information The first screen is intended for normal operation the rest for fault finding The user interface command PAGE q v is used to cycle through them The following sub sectio
43. der computer control otherwise stopped The next field reads in position if the mechanism is either tracking or stopped within a defined position error depending on its requested state The final field shows whether the mechanism can be driven under computer control if not the status shown is Manual override or Engineering mode Lists the type and size of positional offsets 0 to 20 currently defined and any offset in use See OFFSET POSITION ENTER and STORE gives the TV camera currently selected by the TCS see TVCAMERA the guiding pixel coordinates and the state of the guiding loop unlocked or locked see TVGUIDE shows the state enabled disabled of focus corrections for tube and instrument expansion displays the version of TCS software in use Apply a tangent plane offset at a rate defined by the user Format SLOWOFF lt xi gt lt eta gt lt rate gt lt offset_type gt 36 WHT TCS 9 issue 3 3 WHT TCS User Manual Defaults Parameters Keywords Examples Comments lt offset_type gt defaults to ABS lt xi gt lt eta gt are in arcseconds parallel to right ascension and declination in the tangent plane Positive offsets imply that the right ascension and declination of the telescope both increase The magnitude of the offset is independent of position lt rate gt is in arcseconds second in the range 0 1 to 200 lt offset_type gt is o
44. dow Pressing RETURN will keep the default value It is possible for the Display and User windows to be on different devices If the TCS is already running the following menu will be displayed This is the WHT TELESCOPE CONTROL SYSTEM The TCS is running using version W27 1 0 Please enter an option STOP Stop the TCS TELD Start the TELD task NFSMOUNT Mount the ICS Unix partition EXIT Exit this menu and log out EKSE WHT TCS 9 issue 3 3 WHT TCS User Manual Option gt STOP will stop the running TCS then after waiting for 20 seconds for the sub processes to die the START menu will be displayed TELD will start TELD the task which communicates between the TCS and the ICS via DRAMA If TELD is already running it will be stopped and restarted NFSMOUNT will dismount all NFS mounts and remount the ICS Unix partition which is used by the TCS to write the FITS header and also to access user catalogues TELD and NFSMOUNT are not present on the START menu as both actions are part of the TCS startup procedure 2 2 Stopping the TCS Always zenith park the telescope and switch to engineering mode first Under normal circumstances the TCS should be closed down using the TCSEXIT command at the user interface see command list If the user interface is not working e g its window has disappeared or has been accidentally deleted then the
45. e None MARK SUPERNOVA This command stores the current position to allow return to an object at a later date The position is stored in the current input coordinate system 96 S WHT TCS 9 issue 3 3 WHT TCS User Manual 4 38 MOON Display the geocentric and topocentric apparent right ascension and declination of the Moon This command is not allowed from DRAMA or ICL Format MOON Defaults None Parameters None Keywords None 4 39 NEXT Send the telescope to track the source whose data are in the edit source block Format NEXT Defaults None Parameters None Keywords None Comments The user catalogue is searched first followed by the system catalogue The telescope will not move unless both its axes have been zeroset 4 40 OFFSET Offset the telescope by a given amount in right ascension and declination Format OFFSET lt offset_system gt lt offset_ra gt lt offset_dec gt Defaults None Offsets are reset to zero on source change e g GOTO or NEXT Parameters If the ARC keyword is specified see below the offsets in right ascension and declination must be in arcseconds If the TIME keyword is specified see below the offset in right ascension must be entered in seconds of time and offset in declination must be entered in arcseconds Keywords The valid offset systems are ARC offsets the telescope by given amounts parallel to right ascension and declination in the tangen
46. e system computer rather than the TCS and allows other TCS commands to be input during the procedure This means that the autoguider can be used to centre the star as AUTOGUIDE commands will be accepted The ANALYSE keyword can take an optional keyword ZERO or COLL In this case the log file generated by a single POINT _17 WHT TCS 9 issue 3 3 WHT TCS User Manual Examples Comments CALIBRATE command is analysed then the coefficients IA IE or CA JE respectively are calculated and installed CALIBRAT CALIBRATE LAST The CALIBRATE NEW command initiates an automatic sequence which does a restricted pointing measurement on 7 stars from the pointing grid in order to update the values for the encoder zero points in azimuth and elevation and the collimation error in azimuth Stars are selected to be close to the meridian and either North or South of the zenith depending on the initial azimuth A range of elevations must be covered The telescope is driven to the first star and the handset mode is selected When the telescope is tracking the star should be moved on to the reference position using the handset keys Once you are satisfied press F6 This logs the position and drives to the next star If you do not wish to log the star then press I while still in handset mode the star will be skipped and the telescope will drive to the next star Repeat these operations until all 7 positions have been logged You will
47. e it affects only objects with Declinations between 70 66 and 85 62 tracked below the Pole The message is Az limit in again followed by the sidereal time interval The field is left blank if neither limit is relevant Rotator limits This applies to the Cassegrain and Prime rotators only the Nasmyth rotators are allowed to go round continuously The Cassegrain software mount position angle limits are 250 those for Prime are 85 and 273 Which if any rotator limit can be hit is a complicated function of hour angle Declination and starting position angle The messages are Rotator limit in Rotator limit in and No rotator limit followed by the sidereal time interval in the first two cases e Turntable information O O The message STOPPED MOVING TRACKING S W LIM or ENG MODE is displayed with the same meanings as for the telescope except that the software limit can only be encountered during tracking never on source change and the meaning of TRACKING is that the rotator is within 30 arcsec of its demand position equivalent to 0 1 arcsec in position at the maximum field radius The focal station currently selected This means that the software has been configured for that focal station and that the appropriate turntable will be driven It does not refer to the position of the Nasmyth flat The options are CASSEGRAIN default PRIME GHRIL_ROT GHRIL_UVDEROT GHRIL_OPTDEROT GHRIL_NOR
48. e limit positions are o LIMIT 362 o PRE LIMIT 360 o PRE LIMIT 180 o LIMIT 182 Altitude limits As for azimuth except that the final limit refers to the Access Park 3 position which can only be reached under engineering mode control from the balcony The nominal positions are o LIMIT 97 o PRE LIMIT 959 o PRE LIMIT 6 59 o LIMIT 6 0 o FINAL LIMIT 0 75 Prime focus turntable limits There are no pre limits and no cable wrap limits If a hardware limit is hit then the system switches to engineering mode o LIMIT 274 o LIMIT 86 Cassegrain turntable limits There are no pre limits If a limit is hit the drive is turned off and the system switches to engineering mode The turntable must be driven out of the limit using the and buttons on its base or from the engineering desk The Cassegrain cable wrap is driven independently using a simple hardware servo and therefore has its own limits activated if it is more than 75 out of phase with the turntable If it hits one then the turntable must be driven under engineering control until the cable wrap limit is cleared o LIMIT 253 o LIMIT 254 Nasmyth turntable limits Usually the Nasmyth turntables are allowed to rotate continuously as they normally carry derotation optics if anything The GHRIL side limits are used for INTEGRAL to avoid damaging the fibres Warning the status bits may indicate that both limits are SET i
49. e proper motions to correct for the space motion of the object If the epoch is not specified it is assumed to be the same as the equinox Parallax arcsec Generally negligible Defaults to 0 if not specified Radial velocity km s lt 1 positive for a receding object Generally unimportant Defaults to 0 if not specified Differential tracking rates do not form part of a catalogue entry Examples of catalogue files are The simplest possible catalogue containing name RA Dec and equinox 3C567 12 34 45 67 01 23 34 56 B1950 NGC123 00 12 34 56 88 44 22 J2000 COMET 12 12 12 12 33 33 33 3 A A more complicated entry including proper motions SP003 1 124 00 31 22 2 12 24 21 B1950 0 011 17 G158 100 A complete entry S02 15 01 51 27 640 10 20 6 20 J2000 0 00276 0 0390 2000 038 9 3 7 KO 59 WHT TCS 9 issue 3 3 WHT TCS User Manual 7 2 The System Catalogue The TCS has a standard catalogue which is searched automatically by the commands FIND GOCAT and BLIND It contains accurate positions and when available proper motions for a variety of astrometric photometric and spectrophotometric standards The main groups of objects are A grid of bright stars with accurately known positions selected from the FK5 catalogue and used to check the pointing of the telescope e g by CALIBRATE NEW There is a fairly wide range of magnitudes V 1 5 to 7 and spectral types A similar grid wit
50. f they are disconnected This should be ignored Focus limits Hitting a limit stops the focus drive but does not cause a switch to engineering mode o LIMIT 129 5 mm o LIMIT 34 0 mm 55 WHT TCS 9 issue 3 3 WHT TCS User Manual 6 6 Alarms page This page contains alarm indicators for serious faults principally in the hydraulic support system mirror support and power supply All except the dome emergency stop alarm have counterparts on the alarm panel of the engineering desk red light audible alarm The layout is shown in Figure 6 v Oil pump Altitude File Edit Commands Options Print Help Oil pad alarm CLEAR Mains alarm CLEAR Gearbox oil alarm CLEAR Power amplifier WORKING Azimuth oil filter alarm CLEAR Oil temperature NORMAL Mirror height NORMAL Oil level NORMAL Al oil flow divider alarm CLEAR Az oil flow divider alarm CLEAR Dome emergency stop TCS DISPLAY deme CLEAR oil filter alarm CLEAR Nitrogen pressure NORMAL Nasmyth Gate NOT OPEN Figure 6 The alarms screen e Hydraulic and lubrication system O a O Oil pad alarm Indicates high or low pressure at one of the hydraulic support pads Check the engineering desk to ascertain which pad s are involved Warning only does not cause switch to engineering mode Normal state CLEAR alarm state SET Gearbox oil alarm Indicates incorrect oil pressure in the gear boxes Warning only Normal state CLEAR alarm state S
51. fied then the command AUTOGUIDE ON should be used This takes the most recent position received from the autoguider when the command was issued and keeps the guide star there On the other hand if the autoguider coordinates are already known then the appropriate command is AUTOGUIDE ON x y This is likely to be useful when an observation is to be repeated and the field is to be positioned at the same place on the detector The guide probe and pixel positions should be repeated The TCS must know the autoguider in use see AGSELECT otherwise the telescope corrections will be in the wrong direction The function key F8 is equivalent to the AUTOGUIDE OFF command The function key F9 is equivalent to the AUTOGUIDE ON command If the autoguider is not sending packets or if the data is unreliable due to low signal then the AUTOGUIDE command is ignored 4 9 AZIMUTH Move to the specified azimuth and stop Format Defaults Parameters Keywords Examples Comments AZIMUTH lt angle gt None The angle in degrees The azimuth axis has a range of 175 to 355 the absolute encoder has a travel of exactly 360 after which it repeats See WRAP and UNWRAP None AZIMUTH 275 34 The telescope will not move unless the azimuth axis has been zeroset Tracking in altitude and for the current rotator are also disabled by this command 4 10 BEAMSWITCH Offset the telescope so that an image move
52. focal station The corresponding parameters for the default pointing model are also given gives a directory of user catalogues Only the first 50 user catalogues are listed lists the address of each device that is displaying a copy of the display screen displays the parameters of the edit source which will be selected by the NEXT command lists the encoders currently being used by the TCS to control the telescope See ENCODER RATE and SENSOR for information on how to change the configuration gives the current software selection of focal station This option is intended to allow the user to check that the combination of TCS selection of focal station autoguider and instrument is self consistent See STATION INSTRUMENT and AGSELECT lists the software position limits for the main drives rotation all focal stations and focus lists any instrument rotator limits shows the current status of data logging see LOG displays the status of all of the main mechanisms The main drives and the rotator are said to be following during a sidereal track For the dome following means that it is tracking the telescope and for the focus that it is being adjusted to compensate for temperature changes see TRACK The software and hardware limit status for the mechanism is shown next including the cable wrap for the Cassegrain rotator The mechanism is moving if it is being driven un
53. g mode o HORIZONTAL 1 transducer channel 5 o HORIZONTAL 2 transducer channel 6 e Secondary mirror position transducers These are used to measure the tilt of the secondary mirror in its cell Tracking corrections are applied to compensate for the resulting image motion The raw readings are displayed as integers in the range 2047 100 um The readings are expected to fluctuate by 5 or so during normal tracking Wild excursions or unchanging readings indicate problems and should be reported o SECONDARY 1 transducer channel 7 bottom expected range 1200 units 60 um reading 1200 units 60 um at zenith o SECONDARY 2 transducer channel 8 GHRIL side expected range 800 units 40 um reading 0 at zenith o SECONDARY 3 transducer channel 9 GRACE side parameters as for SECONDARY 2 e Temperature sensor readings o GHRIL Up Truss Temp o GRACE Up Truss Temp o Lower Truss Temp o Top end ring Temp 6 5 Limit page This page displays the state of the hardware limits and pre limits for the hour angle declination rotator and focus drives together with emergency stop power and engineering computer mode indicators The layout is shown in Figure 5 DT a OX File Edit Commands Options Print Help Emergency stop RELEASED Computer reset button DISABLED Telescope power ON Mode selected COMPUTER Azimuth ve prelimit CLEAR Azimuth limit CLEAR Azimuth e prelimit CLEAR Azimuth limit
54. gle gt Defaults None Parameters The angle in degrees Keywords None Examples ALTITUDE 85 72 Comments The telescope will not move unless the altitude axis has been zeroset To park the telescope at the zenith without moving it in azimuth type ALTITUDE 90 This is much faster than the hardware ZENITH PARK function or the PARK ZENITH command and is all that is required in most circumstances Tracking in azimuth and for the rotator are also disabled by this command 4 7 APERTURE Offset the telescope so that an object moves by a vector fixed in the focal plane Format APERTURE lt aperture_number gt Defaults None The reference position aperture 0 is selected on startup This is usually also the rotator centre 0 0 Parameters The aperture number is in the range 0 to 20 The corresponding x4 y4 displacement must have been set up previously by using the ENTER or STORE commands APERTURE 0 is the reference position see below Keywords None Examples APERTURE 2 Comments An x4 y4 shift in the focal plane is divided into two parts the reference position which is unaltered on source change and an aperture offset which is reset to zero on source change The APERTURE command provides a means of switching between the reference position and previously defined aperture offsets 4 8 AUTOGUIDE Lock or unlock the CCD autoguider loop Format
55. h stars having V 7 to 9 and a narrow range of spectral types These are more suitable for automatic pointing tests and are used by CALIBRATE FAINT A grid with stars having V 10 to 11 intended primarily for pointing calibrations with the Wide Field Camera Spectrophotometric standards selected from the literature All have accurate positions in many cases considerably more accurate than those tabulated elsewhere Two sets of Landolt UVBRI photometric standards Some sequences suitable for calibration of CCD photmetry Blank fields for sky flat fields Pairs of stars for testing telescope offsetting accuracy The central positions for pairs of stars which may be used to check the IDS slit rotation Bright infra red standards The complete catalogue can be viewed here 60
56. is used to check the performance of the main drives To start accumulating data type RMS SERVO ON or RMS AUTO ON Wait for about 1 minute for ERVO sampling is at 20 Hz or for gt 50 autoguider samples AUTO and then type RMS SERVO OFF or RMS AUTO OFF as appropriate The results of RMS SERVO should be rms errors of lt 0 03 arcsec in azimuth and altitude and means whose absolute values are lt 0 0005 arcsec wn 4 58 ROTATOR Move the rotator to the specified mount or sky position angle or change its mode of operation Format Defaults Parameters Keywords Examples ROTATOR lt rotator_mode gt lt position_ angle gt None lt position_angle gt the position angle in degrees This parameter is only required when using the SKY and MOUNT keywords see below Sky position angle must be in the range 0 to 360 the nearest corresponding mount position angle is selected The Cassegrain rotator has mount position angle limits of 250 to 250 the Nasmyth turntables currently have no limits enabled since they are capable of continuous rotation lt rotator mode gt the following keywords represent the valid rotator modes SKY This keyword gives a position angle on the sky measured anticlockwise from North which is 0 and defined by a natural axis in the instrument such as a spectrograph slit If rotator tracking is enabled as is the case on startup then the rotator will follow this position angle
57. n changes of optical path e g filters When focus tracking is enabled the default state the displayed focus is the virtual position if not the raw encoder reading is displayed 4 28 GOCAT Retrieve the entry for the named source from the user catalogue and then send the telescope to track that source Format GOCAT lt source name gt Defaults None Parameters The name of the target object Keywords None Comments The user catalogue is searched first followed by the system catalogue The telescope will not move unless both its axes have been zeroset 4 29 GOMOON Move the telescope to point at the moon and then track it Format GOMOON Defaults None Parameters None Keywords None Comments The telescope will not move unless both its axes have been zeroset If you stop the telescope while tracking the moon and then wish to continue tracking it use the GOMOON command again Do not use the NEXT command as then the differential track rates will stay constant and will not vary as they should for accurate tracking 4 30 GOTO Move the telescope to a new source and track it Format GOTO lt source name gt lt right_ascension gt lt declination gt lt equinox gt Defaults None Parameters lt source_ name gt The name of the new source It must be a string of up to 20 characters extra characters are lost To include spaces the whole string should be enclosed within double quotes lt right_ascensi
58. n gt lt equinox gt Defaults Name right ascension declination equinox None All other source values User defaults Parameters lt source_ name gt The name of the new source It must be a string of up to 20 characters extra characters are lost To include spaces the whole string should be enclosed within double quotes lt right_ascension gt Specifies the right ascension of the new source in three fields separated by spaces Format lt ra_ hours gt lt ra_minutes gt lt ra_seconds gt The right ascension is rejected if any of the components lie outside the following ranges lt ra_hours gt 0 to 23 inclusive lt ra_minutes gt 0 to 59 inclusive lt ra_seconds gt 0 0 to 59 99 inclusive lt declination gt Specifies the declination of the new source in three fields separated by spaces The lt dec_degrees gt field may be signed If not signed the default is ae WHT TCS 9 issue 3 3 WHT TCS User Manual Keywords Examples Comments Format lt dec_degrees gt lt dec_minutes gt lt dec_seconds gt The declination is rejected if any of the components lie outside the following ranges lt dec_degrees gt 0 to 89 inclusive lt dec_minutes gt 0 to 59 inclusive lt dec_seconds gt 0 0 to 59 99 inclusive lt equinox gt Specifies the equinox of the source coordinates A valid equinox must have two components a leading letter indicating the system of the coordinates and a number indicating the epoch of
59. nd altitude 89 48 respectively The mechanism is driven slowly through the standard position in engineering mode and the encoders are reset when the target is detected electronically in which case the user terminal will bleep and output a suitable message Azimuth and altitude target zerosets may be active simultaneously This is used to cancel a target zeroset request if for some reason it fails This method sets the incremental encoders equal to the absolute encoder for the same mechanism This is done automatically on startup to provide an initial estimate Allows the current position of the mechanism to be input This would normally be derived from the engineering desk synchros in azimuth and altitude or from the scale on the Cassegrain rotator and is corrected for known zero point errors This method provides a starting point for the TARGET procedure and a backup in case of failure of both the absolute encoder and the target electronics This is used to set the zero points in azimuth and or altitude assuming that the telescope is at one of its two hardware park positions This is a useful backup option when there is a problem with one of the absolute encoders since the telescope can be moved to a reproducible position independently of the encoders The PARK and TO keywords both require additional parameters TO PA CT RK RO ALTITUDE ABSOLUTE rT requires lt position gt to be entered in the format l
60. ne of ABS the origin of the offset is the nominal offset position as defined by POSITION 0 ADD the origin of the offset is the current offset i e cumulative SLOWOFF 6 6 2 SLOWOFF 1 5 1 8 0 1 ADD The nominal offset POSITION 0 can be set by the ENTER or STORE commands On source change e g GOTO NEXT the current and nominal offsets are reset to zero The telescope moves from its current position to the offset position at the rate specified Note that the telescope position before the offset is not necessarily at the offset origin if the lt offset_type gt is ABS The SLOWOFF command cannot be used if an OFFSET TIME offset is in use for the current target as tangent plane and incremental offsets should not be mixed 4 65 SNAPSHOT Dump a copy of the information display screen to a file Format SNAPSHOT lt filename gt Parameters lt filename gt is the name of the snapshot file Defaults Directory SNAP_LOG on the telescope computer Extension SNAP Examples SNAPSHOT ARCHIVE Comments This command may be used to record information relevant to an observation or to provide evidence of problems In the case of a problem with the telescope please take a snapshot of each display screen and include the snapshot filenames as output by the TCS in any defect report 4 66 SOURCE Enter new source data into the edit source block Format SOURCE lt source name gt right _ascension gt lt declinatio
61. ng displayed _ 24 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 33 HUMIDITY Enter the value of the relative humidity used in the calculation of refraction Format Defaults Parameters Limits Keywords Examples HUMIDITY lt relative humidity gt None The value assumed on startup is 0 5 The fractional humidity 0 to 1 0 None HUMID 0 5 4 34 INCLUDE Read in a text format source catalogue Format Defaults Parameters Keywords Examples Comments INCLUDE directory lt catalogue_name gt Extension CAT Directory default user catalogue directories The name of the input catalogue None INC USER_CAT SPECPHOT CAT or INC SPECPHOT to input a file called SPECPHOT CAT in the default directory INCLUDE wht cat test cat to input a file prepared on the ICS and placed in wht cat This format is necessary if there is a catalogue file of the same name in the default directory on the TCS computer The default directory on the TCS computer is searched first followed by wht cat the default directory on the ICS The directories are defined in the TCS version file by a logical name search list 4 35 INSTRUMENT Tell the TCS which instrument is in use Format Defaults Parameters Keywords INSTRUMENT lt instrument name gt None The parameters for ISIS are set on startup None Valid instrument names are ISIS ISIS and FOS spectrographs AUXCC
62. ns describe the contents of the pages in more detail 6 2 Source and telescope information The layout of this the default screen is shown in Figure 2 EE oO File Edit Commands Options Print 2006 March 11 9 59 07 S Me 52505 4161 SOURCE BIGDON RA 19 DEC 020 00 00 00 J2000 Aperture NOMINAL Reference X Topocentric AZ 242 i EL 073 12 TELESCOPE TRACKING RA 19 DEC 020 00 00 04 AZ 242 EL 073 13 40 21 Position Error AZ 000 f EL 000 00 00 01 LIMITS Sets in 04 54 No rotator limit TURNTABLE TRACKING Cassegrain Demand Sky PA 600 00 00 Mount PA 036 01 05 Mount Error 000 00 05 Par Angle O55 36 55 98 00mm TC 0 39mm DF mm IT 241 16 Air Mass 1 044 Figure 2 The telescope information display This is the first of the display screens and is the default on startup Its contents are as follows e Time o Date o UT Universal time UTC from the time service o ST Local apparent sidereal time o MJD Modified Julian date i e Julian date 2400000 5 in days AQ WHT TCS 9 issue 3 3 WHT TCS User Manual e Input data for the current source O O O O O O O Name Right ascension Declination Equinox Mean pre IAU76 B post IAU76 J or apparent Differential tracking rates blank if not specified Proper motions and epoch blank if not specified Parallax and radial velocity blank if not specified e Apertures and offsets O O O Positional
63. odes Sign conventions THE TCS DISPLAY General Source and telescope information WHT TCS User Manual 35 35 36 37 37 38 38 39 39 39 40 40 40 41 41 42 42 43 43 43 43 45 45 46 47 49 49 49 WHT TCS 9 issue 3 3 6 3 6 4 6 5 6 6 6 7 7 1 7 2 Encoder display Sensor page Limit page Alarms page Dome status and manual overrides page CATALOGUES Catalogue format The System Catalogue WHT TCS User Manual 52 53 54 56 57 59 59 60 WHT TCS 9 issue 3 3 WHT TCS User Manual 1 INTRODUCTION 1 1 Purpose This document is the User Manual for the Telescope Control Software TCS at the William Herschel Telescope WHT 1 2 Scope This document applies only to the TCS User Interface use of the TCS via the DRAMA and ICL interfaces is not covered 1 3 Definitions right ascension declination parallactic angle sky position angle mount position angle md DE amp a lt lt 3 Cartesian coordinates in the tangent plane parallel to a and respectively Cartesian coordinates in the tangent plane along mount position angle 0 and 90 respectively in the input coordinate system Xa Va Cartesian coordinate system fixed in the focal plane 1 4 Overview The TCS runs on an Alphastation under the VMS operating system Some commands are not available via the DRAMA and ICL interfaces this is noted in the command summary and in the command descriptions
64. on gt Specifies the right ascension of the new source in three fields separated by spaces Format lt ra_ hours gt lt ra_minutes gt lt ra_seconds gt The right ascension is rejected if any of the components lie outside the following ranges lt ra_hours gt 0 to 23 inclusive lt ra_minutes gt 0 to 59 inclusive lt ra_seconds gt 0 0 to 59 99 inclusive lt declination gt Specifies the declination of the new source in three fields separated by spaces The lt dec_degrees gt field may be signed If not signed the default is 23 WHT TCS 9 issue 3 3 WHT TCS User Manual Keywords Examples Comments Format lt dec_degrees gt lt dec_minutes gt lt dec_seconds gt The declination is rejected if any of the components lie outside the following ranges lt dec_degrees gt 0 to 89 inclusive lt dec_minutes gt 0 to 59 inclusive lt dec_seconds gt 0 0 to 59 99 inclusive lt equinox gt Specifies the equinox of the source coordinates A valid equinox must have two components a leading letter indicating the system of the coordinates and a number indicating the epoch of the mean equator and equinox of that system Format lt letter year gt e g B1950 J20000r APPARENT for which no number is required Note that only B J or A are acceptable as leading letters The year must lie in the range 1800 0 to 2100 0 None GOTO HD123456 12 34 56 78 76 54 32 10 J2000 The telescope will not move unless both its axes ha
65. one Keywords lt show_topic gt The following keywords are valid show topics APERTURES ASTROMETRY AUTOGUID Gi wm Displays the x and y4 coordinates of apertures 0 to 20 and the currently selected aperture See APERTURE BEAMSWITCH ENTER and STORE Displays the user modifiable astrometric parameters wavelength pressure temperature relative humidity all used to calculate refraction UT1 UTC and polar motion TDT UTC is also shown as a check on the insertion of leap seconds TDT TAI 32 184 s TAI UTC is an integral number of seconds compare with IERS Bulletin A See WAVELENGTH PRESSURE TEMPERATURE HUMIDITY UTLUTC and POLE gives the autoguider currently selected by the TCS see AGSELECT the associated probe position if relevant see PROBE 35 WHT TCS 9 issue 3 3 CALIBRATE CATALOGU GI wn CLONE op EDIT ENCODERS FOCAL STATION LIMITS LOGGING MECHANISMS POSITIONS TV TCORRECTION VERSION 4 64 SLOWOFF WHT TCS User Manual the guiding pixel coordinates and the state of the guiding loop unlocked locked or suspended see AUTOGUIDE displays the values of elevation index error azimuth index error and azimuth collimation together with their rms errors and the sky sigma for the last CALIBRATE at the current
66. or other peculiar characters The parameters must be in the order Name RA Declination Equinox RA proper motion Dec proper motion Epoch parallax radial velocity The first four parameters are mandatory and the remainder are optional with sensible defaults The formats and units of the necessary parameters are as follows Name up to 20 characters Embedded spaces are allowed but if they are used then the name must be enclosed in double quotes Right ascension hours minutes seconds separated by spaces Declination degrees minutes seconds separated by spaces Equinox For mean places the equinox must have two components a leading letter indicating the system of the coordinates and a number indicating the epoch of the mean equator and equinox of that system The format is lt letter year gt e g B1950 J2000 B denotes the pre I AU76 loosely FK4 system J implies post I AU76 FK5 The year must lie in the range 1800 0 to 2100 0 Geocentric apparent coordinates of the date of observation are denoted APPARENT abbreviable to A No year is required or accepted for apparent coordinates The formats units and defaults of the optional parameters are as follows Proper motions in RA seconds of time per year and Dec seconds of arc per year They default to 0 if not specified Epoch of position year This should not be confused with the equinox The epoch of observation is used in conjunction with th
67. ot yet reached its required position TRACKING the telescope is within 1 arcsecond of its demanded position during a sidereal track TV GUIDE autoguiding on signals provided by the TV system A GUIDE autoguiding on signals provided by the CCD autoguider S W LIM flashing the demanded position is inaccessible This will occur when the telescope tracks into a software limit or on source change when the new object is below the horizon e Telescope position O Right ascension or hour angle and declination displayed only when the telescope is tracking This is in the coordinate system set by the DISPLAY command and indicated by the equinox field see below Equinox usual conventions Topocentric azimuth A and elevation E Position errors in azimuth and elevation Note that the pointing error in azimuth on the sky is AAcosE so a relatively large AA may be tolerated at high declination Note that the coordinate system may be changed using the DISPLAY command The available DISPLAY options are O INPUT default the coordinate system used to input the source data Any space motions have been removed so the position refers to the current epoch If proper 50 WHT TCS 9 issue 3 3 WHT TCS User Manual O O O motions parallax or radial velocity are specified then the position will differ from the input position even in the absence of offsets B1950 available for pre IAU76 mean input coordinate
68. ource block Format Defaults Parameters DEC lt dec_degrees gt lt dec_minutes gt lt dec_seconds gt Value of declination None Sign of declination The declination in degrees minutes and seconds of arc The value is rejected if any of the components lie outside the following ranges dec_degrees 0 to 89 inclusive dec_minutes 0 to 59 inclusive 18 WHT TCS 9 issue 3 3 WHT TCS User Manual dec_seconds 0 0 to 59 99 inclusive Keywords None Examples DEC 12 34 56 78 4 15 DFOCUS Offset the focus to compensate for additional optical elements Format DFOCUS lt focus_ offset gt Defaults None Parameters Focus offset in mm Keywords None Limits 10 to 10 mm Examples DFOCUS 0 3 Comments This command is intended to be used when the telescope focus has to be changed to compensate for the additional optical thickness of a filter The virtual focus reading is unchanged and the focus offset in use is displayed in the DF field on the bottom line of the Information Display 4 16 DIFF_RATES Enter differential tracking rate in right ascension and declination Format Defaults Parameters Keywords Limits Examples Comments DIFF RATES lt diff rate in ra gt lt diff rate in dec gt None Unspecified differential rates are assumed to be zero Right ascension and declination differential tracking rates in seconds second and arcseconds second respectively None
69. ption Defaults option defaults to ENABLE Parameters The outside air temperature in degrees Centigrade Limits 10 to 30 C Keywords Valid option names are ENABLE enable corrections DISABLE disable corrections T Examples TCORRECTION ENABLE TCORRECTION DISABLE Comments On TCS startup corrections are enabled The tube expansion depends on a running average of the GHRIL and GRACE upper truss temperatures In the event of sensor failure an option is to disable the application of a temperature correction When the correction is disabled the TC value on the INFO page will show as zero Corrections Temperature correction is 0 at 5 C At Cass and Nasmyth the focus correction value is 0 1127 mm deg i e temperatures above 5 degrees give a negative TC At prime the value is 0 128 mm deg high temperatures give positive TC See also SHOW TCORRECTION 4 73 TRACK Turn the focus dome rotator or telescope tracking on or off Format TRACK lt mechanism gt lt state gt Defaults None Parameters None Keywords The lt mechanism gt keyword selects the mechanism which is to have its tracking state changed The allowed mechanisms are DOME FOCUS ROTATOR TELESCOPE The lt state gt keyword sets the tracking either ON or OFF Examples TRACK FOCUS OFF 4 74 TRANSFER Control the operational state of remote terminals This command i
70. s POSITION 0 is the nominal offset and is used as the offset origin for tangent plane offsets POSITION 0 is zeroed on source change or if the specified offset is incremental Keywords None Examples POSITION 2 Comments The offset may be tangent plane or incremental depending on the way it was set up SHOW POSITION displays the current list of offsets their types and values 4 49 PRESSURE Enter the value of the barometric pressure used in the calculation of refraction Format PRESSURE lt pressure gt Defaults None The pressure assumed on startup is 779 millibar Parameters The barometric pressure in millibars Limits 750 to 800 mbar Keywords None Examples PRESSURE 779 5 Comments The refraction correction is proportional to the pressure An error of 5 millibar is just about noticeable it corresponds to a pointing deviation of 1 arcsecond at a zenith distance of 75 4 50 PROBE Enter current position of the currently selected autoguider probe Format PROBE lt coordl gt lt coord2 gt Defaults None Parameters The coordinates in um unless otherwise stated Limits Limits for valid autoguiders are as follows CASSEGRAIN 0 to 40000 radius 0 to 180000 millidegrees 6 PRIME 0 to 110000 0 to 20000 AF2 MOVING 128000 to 190000 180000 to 138000 INTEGRAL to 129467 0 to 25506 sssaaa 30 WHT TCS 9 issue 3 3 WHT TCS User Manual
71. s by a vector fixed in the focal plane Format Defaults Parameters Keywords Examples BEAMSWITCH lt offset_x gt lt offset_y gt None On source change e g GOTO offsets are reset to the nominal values this can also be done with the BEAMSWITCH 0 0 or APERTURE 0 commands see APERTURE The aperture x4 y4 positions in arcseconds None BEAMSWITCH 20 2 100 4 11 BLIND_OFFSET WHT TCS 9 issue 3 3 Format Defaults Parameters Keywords Examples Comments BLIND OFFSET lt source name gt None The name of the faint target object None BLIND 0512 22E WHT TCS User Manual This is the standard method for locating very faint objects which are difficult or impossible to see on the acquisition TV or detector Accurate positions for a brightish star and the faint target object must be entered in the catalogue Slew to the bright star using GOCAT and centre it on the reference position with the handset keys Then type BLIND lt source name gt for the faint object This offsets the telescope so that the faint object is accurately aligned with the reference position It can then be moved around the detector using the BEAMSWITCH or APERTURE commands BLIND OFFSET performs a local correction to the pointing model assuming that the position of the reference object is accurate Subsequent executions of BLIND OFFSET all use this correction so several faint objects can be ob
72. s not allowed from DRAMA or ICL Format TRANSFER lt state gt lt remote host gt Defaults None Parameters lt remote_host gt is the IP name or address of the remote host Keywords The lt state gt keyword may take the following values ON Creates a USER window on a remote terminal and enables it as the user interface To return control to the original terminal window either enter CTRL Z on the original terminal or type TRANSFER OFF at the remote terminal OFF Disables the remote terminal entirely returns command input to the control room terminal and clears the remote display Examples TRANSFER ON TRANSFER ON _1px28 40 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 75 TVCAMERA Identify the TV camera currently in use for autoguiding using the GUIDE or I GUIDE options Format Defaults Parameters Keywords Examples Comments TVCAMERA lt camera_name gt None None The lt camera_name gt keyword specifies the TV camera currently in use for autoguiding The options available are SLIT DIRECT Cassegrain slit view 4 5 arcsec mm SLIT REDUCE Cassegrain slit view 12 arcsec mm FIELD DIRECT Cassegrain field view 4 5 arcsec mm FIELD REDUCE Cassegrain field view 12 arcsec mm SH_ CASS Radiospares camera on Shack Hartmann Box at Cassegrain SH_ PRIME Radiospares camera on Shack Hartmann Box at Prime TVCAMERA SLIT REDUCE TVCAMERA
73. s only Current epoch J2000 available for any mean input coordinates Current epoch APPARENT geocentric apparent coordinates of the current date Always available HA TOPO topocentric hour angle and declination Always available e TV autoguider coordinates O If the telescope is being autoguided using a TV camera or CCD autoguider then the pixel coordinates of the requested position of the guide star are displayed together with the latest guide errors converted to arcseconds e Limit information O Elevation limit information this refers to the software limit of 10 If the object is circumpolar the message displayed is No El limit If it is currently visible above the limit but will eventually set the message Sets in together with the sidereal time remaining is shown If the object has set the message is Rises in followed by the sidereal time interval until it becomes visible again Finally for objects which are too far South ever to be seen the message is Never rises Other telescope limits There are two of these which cannot both occur for the same object The first is the zenith blind spot which affects objects with Declinations between 28 55 and 28 97 If the object will track into the blind spot the message Blind spot in followed by the sidereal time remaining is displayed The second is the positive azimuth software limit of 355 This is rarely encountered sinc
74. served using the same reference star The NEXT GOTO and GOCAT commands revert to the default global pointing solution 4 12 CALIBRATE Update pointing coefficients at the start of an observing session Format Defaults Parameters Keywords CALIBRATE lt solution gt CALIBRATE NEW x None Valid keywords are LAST recalls the last pointing solution This may be useful if the running of the control program has been interrupted but does not ensure very accurate pointing because the encoder zero points may have changed DEFAULT reverts to the default pointing solution in the initialisation file This is a suitable course of action if the CALIBRATE command fails e g gives very large rms errors NEW packages a sequence of commands to do a short pointing calibration using bright FK5 stars FAINT does the same as NEW but with a grid of fainter V 9 stars ZEROPOINT logs the current encoder reading and analyses it with a modified TPOINT procedure to calculate and install the 2 encoder zeropoints IA and IE COLLIMATION logs the current encoder reading and analyses it with a modified TPOINT procedure to calculate and install the 2 collimation coefficients CA and IE ANALYSE analyses the pointing log file generated by a series of POINT commands then calculates and installs the coefficients IA IE and CA It is designed to be used when the procedure is run by th
75. system can be stopped from another login session Log in as described in the previous sub section and type STOP at the Option gt prompt WHT TCS 9 issue 3 3 WHT TCS User Manual 3 TCS COMMANDS SUMMARY This section contains a summary of the commands available at the user interface of the telescope control system classified into functional groups Details of individual commands are given in the alphabetical list in the next section Commands which require the telescope or one of its mechanisms to be moved are forbidden in engineering mode 3 1 General TCS commands All allowed in engineering mode HANDSET HELP RECALL and TRANSFER are not allowed from DRAMA e ACKNOWLEDGE Turn off a limit or engineering mode alarm e CLONE Make a copy of the display window on another device e HANDSET Select handset mode e HELP Get help on a command e RECALL Recall a previous command e SAVETCS Save TCS configuration to file e SETTCS Recall TCS configuration from file e TCSEXIT Close down the control system e TRANSFER Transfer control to or from a remote terminal 3 2 Source data entry All allowed in engineering mode e DEC Enter declination of edit source e DIFF RATES Enter non sidereal tracking rates for the edit source e EPOCH Enter epoch of position for edit source e EQUINOX Enter equinox for edit source e PARALLAX Enter parallax of edit source e PM Synon
76. t cat my cat The catalogue can be saved in the default catalogue area on the TCS computer or on the ICS computer use wht cat filename cat in the OUTPUT command to store the catalogue in wht cat filename cat whence it may be recovered on a subsequent night with the INPUT command Old catalogues will be deleted periodically The CAT extension is mandatory any other extension will be removed and CAT substituted T T Display the next page in the cycle of information and status displays Format Defaults Parameters Keywords Examples Comments PAGE lt display screen gt PAGE NEXT the next display screen in the cycle The information display appears on startup None The various displays in the cycle are in order NEXT Display the next page in the cycle INFO Top level information display appears on startup ENCODERS Encoder readings SENSORS Temperature and other sensors LIMITS Limit indicators ALARMS Alarm indicators DOME Dome status and manual overrides PAGE ENC PAGE See Section 6 for more details 4 43 PARALLAX Enter a parallax into the edit source block Format PARALLAX lt parallax_arcsecs gt Defaults None Unspecified parallaxes are assumed to be zero Parameters The parallax in arcseconds Limits The parallax is rejected if it lies outside the range 0 0 to 10 0 arcseconds Keywords None Examples PARALLAX 0
77. t degrees gt lt minutes gt lt seconds gt requires lt position gt to be one of ZENITH the zenith park position or AP1 the access park 1 position See PARK GI GI 7 Z Z Z GI RO AZIMUTH TARGET RO AZ PARK ZEN RO ROT TO 60 00 00 It is important to cancel a target zeroset if it fails to complete The azimuth absolute encoder is broken and is unlikely to be replaced Therefore an azimuth absolute zeroset is not allowed and a target zeroset must be performed before the telescope can be moved in computer mode Care must be taken to ensure that the azimuth target zeroset is carried out in the YELLOW zone 44 WHT TCS 9 issue 3 3 WHT TCS User Manual 5 THE TCS HANDSET 5 1 General The handset provides an interactive way of incrementing the position of the telescope in various coordinate systems setting apertures and offsets and altering the focus and rotator position angle The handset is selected by pressing F6 or typing HANDSET at the user interface Pre defined and user selectable increments may be used and the arrow keys are used to input the steps These auto repeat when held down so a continuous motion may be generated by selecting a small increment and holding down the appropriate key The handset display a variant of that shown in Figure 1 is drawn at the top of the user interface screen HANDSET 0 1 0 3 3 A 30 0 100 0 arcsec Total 0 00 ALT_AZ F8 RA_DEC F9 R
78. t plane Positive offsets imply that the right ascension and declination of the telescope both increase The magnitude of the offset is independent of position TIME offsets the telescope by given amounts in right ascension and declination The magnitude of the offset depends on declination Aa and Ao are assumed to be in the input coordinate system Examples OFFSET ARC 12 6 18 8 OFFSET TIME 0 32 13 4 Comments The origin for OFFSET ARC is the nominal offset stored in POSITION 0 see ENTER and STORE The nominal offset is zeroed on source change OFFSET TIME replaces any previously applied positional offsets 4 41 OUTPUT Write out the current user catalogue in text format to the printer TCS user interface or to a disk file Format OUTPUT lt output_device gt filename Defaults There is no default output device The defaults for the catalogue filename are Node LPAS4 telescope computer Directory device USER CAT 27 WHT TCS 9 issue 3 3 WHT TCS User Manual Keywords Parameters Examples Comments 4 42 PAGE Extension CAT Valid output devices are PRINTER sends the output to the WHT laser printer TERMINAL sends the output to the user input terminal FILE sends the output to a named file The full path for the output file if the FILE keyword is specified see below OUTPUT PRINTER OUTPUT TERMINAL OUTPUT FILE TABBY CAT OUTPUT FILE wh
79. t radial_ velocity gt Defaults Unspecified radial velocities are assumed to be 0 Parameters The radial velocity in km s A positive velocity implies a receding source Keywords None Examples RADIAL VEL 98 Comments The synonym RV can also be used 4 54 RATE THIS COMMAND HAS BEEN DISABLED since it s use is incompatible with normal operation of the telescope Set the encoder used in the azimuth hardware position loop 31 WHT TCS 9 issue 3 3 WHT TCS User Manual Format RATE lt encoder gt Defaults None Parameters None Keywords GEAR The azimuth gear encoder TAPE The azimuth tape encoder Examples RATE TAPE Comments This is a specialist engineering command used to change the source of pulses received by the Marconi servo electronics and used in the hardware part of the position loop Compare ENCODER which changes the encoder combination used by the software part of the loop The command forces a switch to engineering mode Note that changes to the switch settings on the rate generator board are also needed 4 55 RECALL Recall a previous command This command is not allowed from DRAMA or ICL Format RECALL lt n gt RECALL lt string gt or RECALL ALL Parameters lt n gt refers to the nth last command lt string gt is a character string forming the first part of a command to be recalled Qualifiers ALL
80. the chosen sky position angle At a sky position angle of 0 the movements in X_Y and RA DEC are identical RA_ DEC mode is most useful for wandering around finding charts and establishing orientations on the instrument It can also be used for offsetting from a reference source although this can be done more flexibly with other methods such as the BLIND OFFSET command 5 2 3 X_Y mode Changes the demand position in directions fixed in the focal plane units are arcseconds This is the most commonly used of all the modes It moves the telescope in a sensible way corresponding to the customary sense of x y coordinates on the acquisition TV screen or detector independent of rotator orientation and with equal steps in x and y and is the normal method for final alignment of an object on to an instrument aperture such as a spectrograph slit unless the guiding loop is already locked see APOFF below It cannot however be assumed that the same xy increments can be used for more than one observation of the same field The reason is that the handset is being used to compensate both for pointing errors which tend to be functions of azimuth and elevation and therefore rotate with respect to the focal plane when the mount position angle changes and for errors in the position of the object which are fixed on the sky and therefore rotate when the sky position angle changes 46 WHT TCS 9 issue 3 3 WHT TCS User Manual 5 2 4 OFFSET mode This
81. the mean equator and equinox of that system Format lt letter year gt e g B1950 J2000 or APPARENT for which no number is required Note that only B J or A are acceptable as leading letters The year must lie in the range 1800 0 to 2100 0 None SOURCE HD123456 12 34 56 789 11 22 33 44 B1900 SOURCE copies the user default values for all source values into the edit source entry and then takes the command line or prompted input for source name right ascension declination and equinox T 4 67 STATION Select a focal station Format Defaults Keywords Comments 4 68 STOP STATION lt focal_station gt None Valid focal station names are CASSEGRAIN Cassegrain focus PRIME Prime focus GHRIL ROT GHRIL Nasmyth focus with mechanical derotation GHRIL UVROT GHRIL Nasmyth focus with optical derotation UV optimised GHRIL OPTROT GHRIL Nasmyth focus with optical derotation GHRIL NOROT GHRIL Nasmyth focus with no field rotation GRACE ROT GRACE Nasmyth focus with mechanical derotation GRACE _IRDEROT GRACE Nasmyth focus with optical derotation IR optimised GRACE _NOROT GRACE Nasmyth focus with no field rotation Applies the appropriate pointing model and configures the rotator Note that the N asmyth flat cannot be stowed under computer control so the button on the engineering desk must be used for this purpose Stop the named mechanism by ramping the velocity to zero Format Def
82. turn off an alarm caused by an unexpected switch into engineering mode DOME turn off an alarm caused by the dome being out of position ALL turn off any alarm Example ACKNOWLEDGE LIMIT Comments An alarm continuous bleeping is triggered if the telescope or rotator encounters a software limit whilst tracking or when requested to slew to an object below the horizon a switch from computer to engineering mode occurs unexpectedly i e not as a result of an ENGINEERING or TCSEXIT command the dome is out of position by 6 while both the telescope and the dome are tracking 13 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 2 ADD Write the current contents of the edit source block as a new entry in the user catalogue Format ADD Defaults None Parameters None Keywords None 4 3 AGLIMIT Set the limit that determines whether the guidestar is in position Format AGLIMIT lt limit gt Defaults None Parameters The limit in arcseconds Limits 0 to 5 arcseconds Examples AGLIMIT 2 5 Comments This command is useful in conditions of bad seeing when the default limit of 0 5 arcseconds is too small 4 4 AGSELECT Select which autoguider to use Format AGSELECT lt autoguider name gt Defaults None The prime focus autoguider is selected on startup Parameters None Keywords Valid autoguider names are CASSEGRAIN the Cassegrain off axis autoguider CASS
83. us Nasmyth GRACE drive side Nasmyth GHRIL cable wrap side units are degrees minutes seconds o Absolute o Incremental gear e Dome units are degrees minutes e Focus this is the encoder reading without corrections for temperature e Mirror cover e Autoguider packet most recent 6 4 Sensor page This page displays the displacement transducer values and the temperature sensor readings The layout is shown in Figure 4 irspsay sd File Edit Commands Options Print Horiz Displacement GHRIL Up Truss Temp Horiz Displacement GRACE Up Truss Temp Horiz Displacement Top end ring Temp Horiz Displacement Lower Truss Temp Secondary Position Secondary Position Secondary Position Focus LYOT Az Drive Motor 1 Az Drive Motor 2 Figure 4 The sensors screen The values displayed are as follows e Horizontal displacement transducers These are used to correct the azimuth gear encoders for the effects of sideways movements of the telescope They do not affect the tracking if the tape encoder is used The raw readings are displayed as integers in the range 2047 Fluctuations 53 WHT TCS 9 issue 3 3 WHT TCS User Manual should be around 5 units when the telescope is stopped The expected range in computer mode is about 1600 units 120 um The range is limited by the CAMAC ADC values close to 2047 indicate saturation and should be reported Note that the transducers are normally saturated in engineerin
84. use with the APERTURE or POSITION commands When STORE is executed the aperture or offset stored becomes the current one and the Information Display is updated Note that offsets stored after using the handset OFFSET mode OFFSET ARC or SLOWOFF are stored as 6 7 whereas those from OFFSET TIME are stored as Aa Ad STORE POSITION 0 will store the current 7 offset as the nominal offset a Aa Ad offset cannot be stored in position 0 4 70 TCSEXIT Initiate an orderly shutdown of the telescope control system Format Defaults Parameters Keywords Comments TCSEXIT None None None This command stops the telescope before shutting down the control system 4 71 TEMPERATURE Enter the value of the outside air temperature used in the calculation of refraction Format Defaults Parameters Limits Keywords Examples Comments TEMPERATURE lt temperature gt None A temperature of 5 C is assumed on startup The outside air temperature in degrees Centigrade 10 to 30 C None TEMPERATURE 7 5 An error of 10 C gives a pointing error of 1 7 arcseconds at an elevation of 45 39 WHT TCS 9 issue 3 3 WHT TCS User Manual 4 72 TCORRECTION Enable disable that application of focus corrections for tube and instrument ACAM corrections Format TCORRECTION o
85. using the key specified in the table above The seven functions divide naturally into three groups ALT_AZ RA_DEC and X_Y increment the demand position in the input coordinate system and differ only in the directions of the increments The increments displayed are therefore the accumulated values from all three modes in the coordinate system of the current mode The tracking position on the information display also changes OFFSET and APOFF are used in conjunction with the STORE command to set up positional and aperture offsets interactively The tracking coordinates do not change FOCUS and ROTATOR move individual mechanisms Each handset mode is described in more detail below 5 2 1 ALT_AZ mode Changes the demand position in altitude and azimuth units are arcseconds The image is moved horizontally or vertically on the sky Increments are defined in the tangent plane so their magnitudes do not depend on elevation This mode is used to establish the vertical direction e g when worrying about differential refraction or to ascertain whether a failure in telescope tracking or pointing is predominantly in azimuth or elevation 5 2 2 RA_DEC mode Changes the demand position in right ascension and declination units are arcseconds The image is moved in the east west or north south direction Increments are defined in the tangent plane so their magnitudes do not depend on declination Image movement on the TV and detector will depend on
86. ve been zeroset 4 31 HANDSET Place the TCS user interface in handset mode This command is not allowed from DRAMA or ICL Format HANDSET Defaults None Parameters None Keywords None Comments In handset mode the keypad may be used to guide the telescope set up offsets or apertures change the focus or move the rotator See The TCS Handset for a more detailed description This command is bound to the F6 key and to the Do key on a standard Digital keyboard To exit from the handset mode press the F6 key or the Do key on a standard Digital keyboard and control will return to the USER gt prompt 4 32 HELP Provide information about the commands available from the TCS user interface This command is not allowed from DRAMA or ICL Format HELP topic subtopic Defaults Lists all available commands Parameters The command you wish to receive help on Keywords None Examples HELP GOTO EQUINOX Comments Invoking the HELP command initiates an interactive dialogue with the user interface HELP library a normal VMS HELP library In response to a Topic or subtopic prompt you may Type the name of the command topic for which you need help Type a question mark to redisplay recently requested text Press the RETURN key one or more times to exit from HELP Press CTRL Z once to exit from HELP Abbreviate any topic name but note that ambiguous abbreviations result in all matches bei
87. ym for PROPER MOTION q v e PROPER MOTION Enter proper motions of edit source e RA Enter right ascension of edit source e RADIAL VEL Enter radial velocity of edit source e RV Synonym for RADIAL VEL q v e SOURCE Enter name right ascension declination and equinox for edit source 3 3 Catalogue handling All allowed in engineering mode e ADD Add the contents of the edit source block to the catalogue as a named entry e ERASE Clear the user catalogue e FIND Get a named catalogue entry and put it in the edit source block e INCLUDE Append a text catalogue to the current user catalogue e MARK Store the current telescope position as a named catalogue entry e OUTPUT Output the current catalogue to an ASCII file terminal or line printer e REMOVE Delete a catal ntr 10 WHT TCS 9 issue 3 3 WHT TCS User Manual 3 4 Source change None allowed in engineering mode e BLIND OFFSET New source from catalogue with local corrections to the pointing model e GOCAT New source from catalogue specified by name only e GOMOON New source moon coords from sla_DMOON e GOTO New source direct input of name right ascension declination and equinox e NEXT New source using data in edit source block 3 5 Positional and Aperture offsets ENTER is allowed in engineering mode the remainder are not e APERTURE Execute a preset numbered

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