INT Checks
The Wide Field Camera (WFC)

Rev 3.4

Hot Links


  1. First check the Operations Logbook for any restrictions that may be still in force. Turn on the DOME LIGHTS from the console and raise the control room blind.
  2. Make a visual inspection of the observing floor (and the balcony above the control room if the telescope is at ACCESS PARK) to check that the telescope is free to move e.g. No ladders or steps are close to the telescope or test instruments connected.
  3. Moving the telescope out of ACCESS PARK
  4. When the INT is working at prime focus, the telescope is often stowed at ACCESS PARK during the day. This enables the cryostat to be filled or any engineering work on the WFC to be carried out. For the DE checks, the telescope needs to be moved to ZENITH PARK. To do this, on the engineering rack:

  5. Push the LAMP TEST button on the engineering rack. Check that all used indicators are working (e.g. the ALARMS). Replace any defective lamps with new replacements (28v). There should be a supply of these in the cupboard in the control room.
  6. On the engineering rack, test dome rotation manually in both directions by holding down the DOME + then - button for a few seconds. This tests the integrity of the engineering TEM-L system.
  7. If the weather permits, open the dome shutter a small amount, but see important note below.
  8. Use RAISE MICRO (until the OVERTRAVEL indicator goes off) then push RAISE MAIN. To close the shutter, push LOWER MAIN and when the shutter stops moving down in fast motion, use LOWER MICRO to fully close the shutter.

    n.b. If the dome or shutter does NOT work from the engineering rack push buttons, check the manual controls on the large grey cabinet mounted on the dome. Access is via the balcony above the control room. The switches (some key operated) associated with the dome and shutters must be pointing to REMOTE. They may have been switched to LOCAL.


    The tests for opening the shutters only applies if they are working correctly. If any mechanical problems exist then do NOT do these checks. Provisional instructions for TO's on how to open/close the dome will have been issued if this is the case.

  9. Push and hold the PRIMARY MIRROR OPEN button. Check the mirror petals open fully. Push and hold the PRIMARY MIRROR CLOSE button to close the petals.


It is important to shut down and restart the INT computers when doing the daily checks. This especially applies to the DAS and ICS computers where memory leaks can cause problems.

The INT observing system comprises of four computers. These being:

    Logging out from the ICS and DAS

  1. On the INT ICS computer, kill the WFC GUI by choosing quit from its menu.
  2. In the pink window at the SYS> prompt:
  3. SYS> shutdownobssys
    Do you want to wipe out the system Y/N? y
    SYS> exit
  4. On the orange DAS window, enter at the DAS> prompt :
  5. DAS> shutdownobssys
    DAS> exit

    Exiting from this window logs you off the DAS computer.

  6. Log out from the INT ICS. Click the right mouse button when the mouse pointer is over the blue background window and choose the "exit" option at the bottom of the menu. This will terminate your login session. Any residual windows will be killed off in the process.
  7. Logging out from the Data Reduction LINUX PC

  8. In the IRAF window, at the  ecl>  or  in>  prompt. To exit type: lo
  9. Close any remaining windows and exit the system as previously shown.

    Logging out from the TCS

  10. The TCS is run from an X window on the INT TV machine. In the USER window, type:
    USER> tcsexit


  1. Log on at the console of the INT TV computer using the CDE (Common Desktop Environment) window manager:
    Username: intobs
    Password: ****** (as shown on monitor)
  2. Start another xterm window and establish a telnet session to the machine inttcs (e.g. telnet inttcs).  When prompted, login as shown:
    Username: INT_LOGIN
    Password: ********* (as shown on the monitor)
  3. The following menu will be be displayed :

    Last interactive login ...
    Last non-interactive login ...

    Set up for TCS version I27-2-0 (version used 08/06/2011)

    %DCL-I-SUPERSEDE, previous value of TELESCOPE has been superseded
    %DCL-I-SUPERSEDE, previous value of DRAMADISK has been superseded
    %DCL-I-SUPERSEDE, previous value of XSERVER has been superseded
    %DCL-I-SUPERSEDE, previous value of DECW$DISPLAY has been superseded
    The X client is LPAS2
    The X server is a remote X terminal or computer connected via TCP/IP.


    The TCS is not running.

    Please enter an option -

    START - Start the TCS version I27-2-0
    Info display on
    USER window on

    SIMULATE - Run the TCS version I27-2-0 in simulation mode
    Info display on
    USER window on

    VERSION - Select a different TCS version

    DISPLAY - Select different display devices

    EXIT - Exit this menu and log out


    If the above screen does not appear please see the troubleshooting section (item 2).


  4. By default both the Info Display and the USER window will be displayed on inttv.  However, this can be changed by using the DISPLAY option.  In reality the windows can be displayed on any X-window system.  In practice, it's recommended that the INT TV computer be used for this purpose.  If the machine inttv is not shown, use the DISPLAY command to configure the display option

    Option> DISPLAY

    Enter IP name or address for DISPLAY window

    > inttv
    %DCL-I-SUPERSEDE, previous value of DISPLAY_XSERVER has been superseded %DCL-I-SUPERSEDE, previous value of DEFAULT_DISPLAY_XSERVER has been superseded

    Enter IP name or address for USER window

    > inttv
    %DCL-I-SUPERSEDE, previous value of USER_XSERVER has been superseded %DCL-I-SUPERSEDE, previous value of DEFAULT_USER_XSERVER has been superseded


  5. Now to start the TCS, from the prompt use "START" command:
    Option> start

    Check that the User and Infodisplay windows appear on the INT ICS.

  6.    Position these windows on the right-hand screen.

  7. On the engineering rack, push the Oil Pump RUN button. Wait until the OIL ALARM indicator lamp on the console has gone out.
  8. Zerosetting the telescope

  9. Visually check that the telescope is near zenith park. (i.e. vertical). The HA synchro position indicator pointers should be near the "12 o'clock" position with the DEC indicator pointers near the "9:45 o'clock" position. If the position indicators are some way off, move the telescope close to these positions using the HA and DEC +/- buttons on the engineering rack. Select quick motion (QM) if the telescope is a long way off position then go to slow motion (SM) to make the final adjustments.


  11. In the TCS User window, enter:
  12. USER> zeroset ha target
    USER> zeroset dec target
  13. Using the HA and DEC +/- buttons with slow motion (SM) selected and the drive rate controls adjusted for a very slow speed, move the telescope so that the synchro dial pointers MOVE THROUGH the "12 o'clock" position in HA and the "9:45 o'clock" position in DEC.
  14. n.b. The synchro pointers are slightly misaligned and the zerosets will occur a short distance away from their nominal positions. Markers have been placed against the HA and DEC synchro dials to where this should happen.

    The TCS will beep if the zeroset is successful. The yellow LED's mounted above the synchro dials will momentarily flash also confirming that the telescope has been zeroset.

  15. Sony incremental focus encoder check

    On the TCS, type:

    to check that the absolute and incremental encoders agree. Move the focus in engineering mode and check that the encoders still agree. If they do, type:
    to see which focus encoder is IN USE. If it is the absolute encoder, type:
    to switch to the incremental encoder which is more accurate and now used for focus/temp tracking.

    n.b. If the encoders do NOT agree or there is a problem with the Sony encoder, follow the link to: Sony focus encoder Info or refer to the appendix pages in the INT DE CHECKS folder.

  16. Testing the telescope in Computer Mode

  17. Put the telescope into Computer Mode by turning the COMP keyswitch. The green section of the ENG/COMP push button switch should illuminate showing that Computer Mode has been selected.

    n.b. The HA and DEC slow motion (SM) push buttons MUST be set for SM mode (i.e. All the lower green sections of the buttons illuminated) before Computer Mode can be selected. If the yellow section of a QM button is illuminated, push the adjacent SM button to re-engage the slow motion clamps. Computer Mode should now be available.


  19. Check the Local Sidereal Time display. The telescope can be safely moved in RA +/- 3 hours away from the LST as displayed.


  21. Enter a value of RA either +/- 1 hour away from the displayed LST.

    In Dec, a good position for checking the telescope is at the celestial equator. This will position the telescope tube at right angles to the polar axis.

    Format for entering telescope co-ordinates is :

    USER> source name hh mm ss dd mm ss equinox
    name        No more than 20 characters
    hh mm ss    RA   hrs mins secs
    dd mm ss    DEC  +/- degs mins secs
    equinox     Usually J2000
    Example: LST is at 15:30:00
    USER> source TEST 16 30 0 0 0 0 J2000
    USER> n
  22. Check that the telescope gets into Tracking mode and that the dome moves.

    n.b. If the dome does NOT move, it may have been overridden? On the console there is a bank of five push buttons called SELECT MANUAL CONTROLS. Check that the first button labelled DOME/SHUTTERS has not been set.


  24. Put the telescope back to zenith park.
  25. USER> park zen
  26. Return the telescope to Engineering Mode by typing :
    USER> eng
    or by pushing the ENG/COMP button. Type "ack" to stop the TCS alarm if this button has been pressed.
  27. Switch off the OIL PUMP and push the red ACCEPT button to mute the alarm.


n.b. Always bring up the DAS before starting the ICS. When shutting down, do this in the reverse order.
  1. Log on at the console of the System computer :
  2.   (using OpenWindows)
    Username: intobs
    Password: ****** (as shown on monitor)
    Two xterm windows appear: one with a pink background, logged in to the System computer and one with an offensive orange background logged in (via rlogin) to the DAS computer.

  3. In the orange window (triton), enter :   obssys

    Check the whiteboard in the control room for the current WFC observing system option number. (e.g. 4) and enter this number.

    Observing systems available:
    7: IDS+EEV10
    6: IDS+TEK5
    5: Shack-Hartmann Test
    4: WFC
    0: give up and exit


  4. When this has been done, in the same window enter :
    and check the messages for any errors.
  5. Eventually, you should get the prompt :
    If there were no errors then the DAS is now ready.


  7. Minimise the orange window.

  9. In the pink window, enter :
  10. Choose the menu option number that was used when starting up the DAS. This must be the same.


  12. In the same window, enter :
  13. Check that you have the prompt:  SYS>   and at least the following windows on either the ICS monitor or it's second display screen :

    After the mimic has started and communications have been set up, the software will carry out some self tests on the WFC. Check the mimic for :


  14. Check that you can send commands to the TCS from the ICS
  15. n.b. You will have to be in COMPUTER MODE to carry out these checks.

    Move the FOCUS.

    Make a note of the telescope focus and send it to a different position.
    n.b. The focus for the WFC is norminally 45.0mm


    SYS> focus 43.8
    Check that the focus moves to the demanded position. Return the focus back to where it was after testing.

  16. The ICS is now ready to rock 'n' roll !


The WFC CCD mosaic array consists of 4 thinned EEV chips. With the current software in the CCD controller, the raster from each CCD has 2054 x 4200 pixels. Commands can be entered at the SYS> prompt or by clicking with the mouse on the buttons on the WFC mimic/graphical user interface (GUI). For the DE checks, it is usually more convenient to use the WFC GUI.
  1. Check on the observing-log display that there is enough space available for tonight's observing run.  This is monitored automatically by the Computing Group and should not represent a problem.  UltraDAS will use the observing disk that has the maximum amount of available disk space, changing discs as each one fills up. The data disks are called /obsdata/inta, /obsdata/intb etc.

  2. Check to see that the status box line at the top of the GUI is all GREEN. Status boxes are displayed for :
  3. MCA

    of which MCA is the shutter-control program on the INT ICS computer, WFC is the camera-server program on the DAS computer, TCS is the TCS agent on the Telescope computer, AUTO is the autoguider server on the Autoguider computer and HCT is the header-collection task on the ICS.

    If any of these boxes are ORANGE then a WFC drama task is not present and will need to be investigated.  For example, if the TCS is not running, then the box will be orange.


  4. Click on the enable button at the top right hand corner of the GUI to enable interactive operations. The 'greyed out' text on radio buttons will now change to black.
  5. Checking the BIAS frames

  6. Make sure that the dome lights are off and the control room blind is down.
  7. Ignore the readout-speed buttons; the current CCD controller always works in fast speed.
  8. Click on the Bias radio button to select that type of observation. Click on the Run button to start a normal observation. The boxes for the CCD mosaic readout status will now change colour from GREEN to BLUE . The progress of the CCD mosaic reading out, processing the pixel stream into separate images and writing to disc is shown on the mimic.
  9. Whilst the bias frames are reading out, start an IRAF session:

  10. Log on to the INT Data-Reduction computer (intdrpc):
  11. Username: intguest
    Password: ******** (as shown on monitor)
    From Applications/System Tools or the desktop top-left corner start a Terminal. Type 'iraf' in the terminal. This will start all necessary windows and applications to run IRAF.

    Alternatively you may start a Xterm window, a command window for IRAF and an image display manually:

    ds9 &
    xgterm -sb &
    n.b. These can also be started from the programs menu selected by right clicking the mouse on the blue background and clicking on xgterm and ds9 from the drop down menu.

    In the Xgterm window, run IRAF's command interpreter by typing:  cl
    The prompt will now be:


    Load the ING's IRAF script files by typing:

    ecl> wfc_ql
    The prompt will now change to:
    n.b. If this is not done, the WFC display command will not be found.

  12. Look on the WFC mimic to see where your bias observation is being written. In the IRAF window, move into the "date" directory where the images are stored. The path is shown below with the current date entered in the format:

    yyyymmdd   e.g.

    wfc_ql> cd /obsdata/inta/20110608/
  13. Check that the progress indicators for reading out, processing and file writing all go to 100%. The boxes will then change colour back to green.
  14. When the bias frames have read out, the computer will beep. Check in the observing-log window that the run has been logged. There should be one line covering the data from all four CCDs. Check that the TCS data (RA, Dec, equinox etc.) are logged. If they are not there, then the DRAMA link from the System computer to the TCS is probably broken.
  15. Displaying the bias frames

  16. Go into the IRAF window and type:
  17. wfc_ql> wfc_display r<run-number>
    This loads the images from the CCDs into the four frame-buffers of ds9 and displays them as a tiled image. Calculations are made on the bias regions of the CCDs and the statistics displayed. You can use DS9's CONTROL PANEL option to zoom in or out or change the colour look up table if desired. n.b. The image default is 'greyscale'.

    Examining the image

    You can also use imexam to get a more detailed analysis of the images.

  18. In the IRAF window, enter:
    wfc_ql> imexam
    Move the mouse over the area of the displayed frame and left click.
  19. Move the mouse around the image area, typing "m". This will produce statistics for a box of 25 pixels around the mouse cursor. The RMS noise values should lie between 2 to 3 on all four chips.

    More precise data on the WFC mosaic camera can be found at:

  20. If there are white spots, move the mouse over them and type "s". This will produce a surface plot. Check that the white dots are single pixels.
  21. To exit imexam, leave the mouse cursor over the image area and type "q".
  22. Repeat the check on the other three CCDs.

This completes the CCD mosaic checks.


For a more detailed description of the WFC autoguider and performance checkout, follow the link:
INT WFC Autoguider

The WFC Autoguider consists of a 2048 x 2048 thinned Loral CCD fitted alongside the science mosaic ccds within the cryostat. Half of the chip is masked off to provide an area for fast frame transfer. The effective imaging area is 2048 x 1024. n.b. It should be noted that the autoguider chip is BELOW THE SHUTTER and can only see light when the shutter is OPEN.

  1. Check that the autoguider window is present on the ICS display.
  2. Check that the autoguider is light sensitive by first opening the shutter of the WFC by clicking the OPEN radio button on the mimic.
  3. Click on the FIELD radio button in the autoguider window to take an exposure. The integration period defaults to 1 second and with little or only scattered light in the dome will probably cause the CCD to saturate. This test only works if the main filter passes a reasonable amount of light. Stray light within the dome due to light leaks is usually sufficient. Avoid the U, I and Z filters for this test.
  4. CLOSE the shutter from the mimic and click on FIELD to take a second exposure. The image should now be flat with no patterning or streaks on the display.
  5. Click on the TV radio button. The autoguider should now be updating it's display at regular intervals.
  6. Click on STOP to halt the continuous readout.
  7. The autoguider checks are completed.


Moving the telescope back to ACCESS PARK

To do this, on the engineering rack :

Filling the WFC Cryostat

The WFC cryostat (BIG BERTHA) holds 6 litres of N2 and should stay cold for 24 hrs, but it's advisable to top it up AFTER doing the DE checks. Slewing the telescope or moving the prime focus rotator to some positions can tip out liquid nitrogen from the cryostat.

Always remember to leave the PRESSURE RELEASE valve on the dewar OPEN. If this is forgotten, pressure can build up over time and burst the relief valve on the dewar. Especially if the dewar is close to full.


Back in the control room. Turn OFF the dome lights and ...
Don't forget to tick off the checks as completed and to sign off in the logbook.  If, for whatever reason, checks are not completed, this should also be noted in the logbook.  However the WFC cryostat must always be filled.



  1. The Filter Wheel
    On WFC startup, it is NOT uncommon for the MCA controller (the electronics crate mounted under the WFC which drives the shutter and filter wheel), to have problems identifying the filters which are loaded. In this case, it may be necessary to send, perhaps several times, the command:
    SYS> cmd MCA RESET
    Furthermore, the filter wheel and the shutter may be thoroughly exercised by issuing the following commands :
    SYS> McaTest 
    This exercises both the shutter and filter wheel (14 operations). Run this test at least twice.
    SYS> filter_test 
    Tests only the filter wheel and performs 70 moves.
  2. If the TCS is already running, for example someone has logged out of the INT TV without stopping the TCS, the following screen will be displayed:
Last interactive login on ...
Last non-interactive login on ...

Set up for TCS version I27-2-0 (version used 08/06/2011)

%DCL-I-SUPERSEDE, previous value of TELESCOPE has been superseded
%DCL-I-SUPERSEDE, previous value of DRAMADISK has been superseded
%DCL-I-SUPERSEDE, previous value of XSERVER has been superseded
%DCL-I-SUPERSEDE, previous value of DECW$DISPLAY has been superseded
The X client is LPAS2
The X server is a remote X terminal or computer connected via TCP/IP.


The TCS is running, using version I27-2-0

Please enter an option -


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


Under these conditions the TCS needs to be stopped by using the STOP command.  Now return to the section entitled "Starting up the TCS and Telescope Checks".

Document History

Rev 1.0 First issued: Mar 23rd 1999  John Mills
Rev 1.1 Changes regarding WFC checkout and ICS to TCS commands: Mar 28th 1999  John Mills
Rev 1.2 Access park procedures added: Mar 30th 1999  John Mills
Rev 1.3 Error found in moving out of access park procedure. Corrected: Apr 8th 1999  John Mills
Rev 1.4 Updated for system s8.2 and UltraDAS: Sep 2nd 1999  Guy Rixon (UK ATC)
Rev 1.5 Displaying bias frames re-edited: Mar 14th 2000  John Mills
Rev 1.6 LN2 dewar earthing added: Oct 5th 2000  John Mills
Rev 1.7 Minor changes made: Apr 27th 2001  John Mills
Rev 1.8 Minor changes made: Sep 19th 2001  John Mills
Rev 1.9 INTICS changed to lpss7: Oct 29th 2001  John Mills
Rev 2.0 Updated and added MCA test scripts: Feb 5th 2002  John Mills
Rev 2.1 Sony Focus encoder info added: Jun 5th 2002  John Mills
Rev 2.2 Removed machine names. Generic names only now: July 15th 2002  John Mills
Rev 2.3 Wording changed from 'Shutting down' to 'Logging out from' the INT Observing System: Sep 12th 2002  John Mills
Rev 3.0 TCS section changed to remove dependency on the X Terminal: Jun 6th 2005  Don Carlos Abrams
Rev 3.1
Updated to reflect the change in IRAF: Jun 18th 2005  Don Carlos Abrams
Rev 3.2 New TCS procedure added: Sep 25th 2006  Don Carlos Abrams
Rev 3.3 IRAF package to be used is 'wfc_ql': Oct 1st 2009  Jürg Rey
Rev 3.4 LINUX DAS: June 8th  Jürg Rey

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