AAO Wide Field Imager & Prime Focus Unit

Imaging Cookbook.


Version 1.1 - 19 February 2002

Chris Tinney

Useful WFI links



    1. Introduction
    2. WFI at the AAT
      1. Where to find more details
      2. WFI Background
      3. WFI Layout on Sky
      4. Differences between WFI and OBSERVER
      5. The WFI Hardware
    3. Shutting Down
    4. Startup
      1. Start the PFU Widget
      2. Start the WFI_TEL_CONTROL task
      3. Start the WFI Cicada system
      4. After Starting WFI/Cicada (and before observing)
    5. A Tour of the WFI Cicada Interface
    6. Observing with WFI and Cicada
      1. Looking at your data
      2. In the Afternoon
      3. Start of the Night
      4. In the Morning
    7. Using prepared scripts
    8. Writing scripts
    9. Guiding
      1. Should I guide?
      2. The Multiplexer & MaximDL Software
      3. GSFIND and the AAT_TELESCOPE task
      4. Guiding - Step-by-Step
    10. Saving your data.
      1. Formats
      2. Drives
      3. Writing a Tape
      4. Writing more data to a tape which already has data on it.
    11. Frequently Encountered Problems, or "Things that go wrong when I do xxx ... "
      1. Things that go wrong when I try to start Cicada/WFI
      2. Things that go wrong when I try to take data
      3. Things that go wrong when WFI talks to the telescope
      4. Things that go wrong with PFU
      5. Things that go wrong with the focal plane temperature
    12. Frequently Made Mistakes
    13. Frequently Asked Questions
    14. Appendices
      1. Twilight Flat Fields
      2. Other bits of Cicada you might want to know about

1. How to use this Cookbook

This cookbook provides information on the use of the 8K Wide Field Imager mosaic at the AAT for observers.  It is targetted specifcally at observers preparing for, or carrying out their run. If you want information to prepare an observing proposal, look at the WFI Performance at the AAT page, and for guidance on data reduction see the Data Reduction Guide.

Section 2 is a Short Guide to WFI and PFU and their hardware. Section 3 describes shutdown procedures. Section 4 describes startup procedures and what you need to do at the start of each night. Section 5 is a guide to the WFI Cicada control panel. Section 6 is a step-by-step guide to typical observing procedures with WFI. Sections 7 and 8 describe the use of scripts to set up more complex exposure sequences, including dithering, automatic focus adjustment, observing standard stars, etc. Section 9 describes guiding procedures.  Section 10 covers writing your data.  Sections 11-12 are the Frequently Encountered Problems, Frequently Made Mistakes and Frequently Asked Qustions pages. Some Appendices are included at the end.

What should your read? Well the lot obviously. For the impatient here are the important bits.

Impatient People Preparing for a Run :  Read Short Guide, the Guide to the WFI Cicada Control Panel, the Observing Guide and the Frequently Encountered Problems, Frequently Made Mistakes and Frequently Asked Qustions.

Impatient People at the Telescope : If you aren't going to guide, you can skip the guiding section. But read the rest. Really, you'll save a lot of trouble if you do.

2. WFI at the AAT - A Short Guide

2.1 Where to find more details

Astronomers interested in proposing to use Wide Field Imager (WFI) at the AAT should see the WFI Performance at the AAT page (and the links there to the WWW S/N Calculator), which also contains a detailed description of WFI's performance, as measured at the AAT. The following is only a brief summary.

2.2 WFI Background

WFI is an CCD imaging mosaic, consisting of eight 2Kx4K MIT Lincoln Labs 15um edge-buttable CCDs, arranged to give an 8Kx8K imaging format. It is mounted at the triplet corrected f/3.3 prime focus of the AAT on the AAO Prime Focus Unit (PFU), and has a field of view of roughly 33' on a side. The WFI focal plane also includes 8 small guide CCDs.

WFI is shared facility which was constructed as a collaboration between the Research School of Astronomy & Astrophysics (RSAA) of the Australian National University, the Anglo-Australian Observatory, the University of Melbourne, and Auspace. Its use is shared between the RSAA 40" telescope on SSO and the AAT. While the WFI mosaic itself moves between the AAT and the 40", each telescope has its own "exposure controller" (i.e. shutter and filter wheel).

Prime Focus Unit (PFU) is the AAT's exposure controller.  It contains a six position filter wheel able to hold filters up to 165mmx165mm in size, and 10mm thick. It also contains a two-travelling-blade shutter, able to uniformly expose the entire focal plane at better than 1% for exposures longer than 2s.

The entire 128Mb WFI 8K image is read from the CCDs using 8 parallel controller channels, displayed in real time, and transferred to disk in 58-60s (depending on computer load). The data are written to disk as multi-extension FITS files.

2.3 WFI Layout on Sky

The following diagram (also available in postscript for printing out) shows the layout of the WFI detectors (and the eight guide detectors) on the sky.

2.4 Differences between WFI and OBSERVER

WFI is run under the RSAA's Cicada data taking system, not the AAO's OBSERVER system. As a result observers who are familiar with OBSERVER need to be a little careful of a few differences.

2.5 The WFI Hardware

Most observers will never need to interact with the WFI or PFU hardware, other than perhaps changing filters. However, here's a brief guided tour of the equipment.
WFI sitting in the Prime Focus cage. Viewed when the 
telescope is at Prime Focus access.
Annotated detail of the PFU and WFI.
PFU Filter loading door, showing bar-code reader used to identify filters when the filter wheel is initialised. PFU Filter door open showing a filter mounted in the wheel. Each filter sits in a small metal holder, from which it is never removed. The thing white strip to the left of the filter is the braced mounted on the filter holder.

3. Shutting down

Shutting down CICADA

First exit the WFI window, and then exit the Cicada window. If the Ximtool window doesn't vanish, then close that as well. Then type cicada_cleanup in the window where you initially started cicada.

Shutting down PFU

You should not need to do this. You can shut down WFI and re-start it without re-starting the PFU task.

Should you need to shut down the widget, just use the "Exit" button. Then type "exit" to exit drama, in the aatpfu terminal window from which you started the widget, and "exit" again to log you completely out of aatpfu.

If for any reason you need to power off aatpfu, then it is very important to shut it down first, by typing "shutdown -h now" instead of the second exit. Once the computer is shut down you can turn it off.

Shutting down the WFI_TEL_CONTROL Task

You should not need to do this. You can shut down WFI and re-start it without re-starting the telescope interface task

If you do want to re-start it, just hit <Ctrl><C> in the wfi_tel_control window, and then log out of aat40a.

4. Startup

The following instructions for starting up the PFU and WFI do not contain user login names or passwords (for the obvious security reasons). These can be found on a piece of paper on the wall next to the WFI console.

4.1. Start the PFU Widget

The PFU is run from a Linux PC  (aatpfu) mounted in the prime focus cage. A task on this PC allows both the WFI CCD controllers to run the shutter, and for the WFI Cicada system to run the filter wheel. This task should be running before before you try to start Cicada running. (In debugging or set up this may be done by a keyboard and screen plugged directly into aatpfu). In normal operation this is done by remotely connecting as follows
  1. Start a terminal window and connect or telnet to aatpfu.aao.gov.au (or

  2. On the usual x-terminal used for this (aatxtl) this will look like so...
  3. If you are on a Sparcstation, allow aatpfu to pop up a window by  typing xhost aatpfu or xhost
  4. Login using the username and password located on the wall near aatssx.
  5. Type drama.
  6. Type cleanup.
  7. Type dtk -t tk2.tcl - you should see a widget like the following appear (though the filters slots will be blank).
  8. Then click the buttons to "Initialise shutter", "Initialise Filter" (this takes a few minutes), and "Read Filter". Once the filter wheel has finished initialising, PFU is ready.

Sometimes the "Initialise Filter" "Read Filter" will fail to read one or more barricades when the telescope is at prime focus access. Ask the support astronomer, afternoon technician or night assistant to move the telescope to the zenith and repeat the Initialise Filter (followed by the Read Filter). If its still failing you may have a low pneumatic pressure or filter blockage problem.

4.2. Start the WFI_TEL_CONTROL task

This task mediates communication between WFI and the AAT telescope control system (TCS). Connect to the AAT40A from an X-terminal (you must use an X-terminal for this).  Then login using the username and password on the wall near aatssx, and start wfi_tel_control.
    40a>  wfi_tel_control
This task will then wait for requests for telescope information from the WFI Cicada system. You should see positions etc. regularly spat out here at the end of each exposure (or if the AAT_TELESCOPE task is updating).

4.3. Start the WFI Cicada system

Login to the WFI console (aatssx) - usernames and passwords are on the wall.

Then at a unix line prompt type

> cicada_cleanup
> cicada
In a few moments a tiny little obscure looking widget will pop up near the top left of the console screen. This is the Cicada panel.
On the "Start Observing" pull down menu at the left you'll find a few options. Choose "WFI" and the WFI panel will appear. (The other option "WFI_BottomStandalone" should only be used if one of the controllers fails and you can only read 4 CCDs instead of the full 8).
If all goes well, and you have been able to correctly start up the TEL_TASK and the PFU widget before starting Cicada. If you get a nasty red message about a failure of the filter task, then it may mean you haven't started the PFU widget. See the things that go wrong when starting Cicada/WFI.

The first thing you may notice is that the "Open Shutter/Close Shutter" button at the bottom is yellow and says "Close Shutter". For some reason the WFI task starts its idea of where the shutter is,  in a confused state. Click on this and it will clear itself.

This panel is the one you'll use to control WFI almost all  of the time. Its pretty straightforward. But  before you start observing there are a few things you need to do, so we'll cover them first.  You should make sure you do the following well before you want to take your first flats in the evening - if there's a problem starting cicada its easy to lose 10 minutes, which can really stuff you up, if the sky is rapidly fading.

4.4 After Starting Cicada (and before observing)

After starting Cicada (and before you start observing) you need to do the following :
4.4.1. Update the location the data is written to, the file prefix, and the starting run number. You must do this correctly, otherwise your data can't be properly archived.
      Click "Options" "Preferences" to bring up the preferences dialogue. Then choose "General"


      1. Set the Prefix: to the appropriate date.

      2. You must use the nnmmm (i.e. 05mar, 30dec etc.) format shown above.
      3. Set the Directory:  to the appropriate date.

      4. You must use the /wfi_{raw,data}?/cicada/YYYYMMDD/A format shown above.

        There are four disks available for your data /wfi_raw1, /wfi_raw2 (both 70Gb), /wfi_data1, /wfi_data2 (both 18Gb). Mostly you'll use wfi_raw1 and wfi_raw2. Other than choosing the disk you want, you must follow the date format shown above, and you must end it with capital "A". This is again to mimic the archiving used on the AAO's in-house observing system, so the night assistant can archive the file headers and make an observing log.

        Once the location for files has been set it will stay that way until you change it - so this only needs to be done once at the start of each day's observing.

      The rest of the options here (and in the other "Preferences" categories) can be changed as you wish, but the defaults will generally be the most useful. Use 'Ok' to dismiss this window when done.
    4.4.2. Start & Update the AAT_Filter Task
      Under the "Instrument Controls" pull down you'll find two options. One is AAT_FILTER task. Start this and the filter panel will appear. By clicking on the filter buttons here, you will send commands to the PFU, and the filter will be changed.

      It is important to note that although the PFU reads bar-code identifications from filters, and passes those filter identifications back to Cicada to get included in file headers, Cicada itself pays no attention to these names. The only filter names Cicada knows about are the filter names hard coded into the AAT_Filter task.

      So, if you change the filters in the PFU, therefore, you not only need to reinitialize the filter wheel of PFU, but also update the AAT_FILTER parameters, and then re-start CICADA. Do this as follows.

      Under "Options"->"Hardware Configuration ... " (this only works when running Cicada logged in as wfieng. If you're logged in as wfiobs, you'll need to exit, and log in as wfieng to make this change). Use "Category:" at the top to choose Filters, and the select AAT_FILTER from the list at the left.

      Please be very careful. You have intimate control over the hardware configurations of WFI here, and can really screw things up. Only make changes in the filter boxes as described below. Change nothing else!

      You'll see the filter names in 6 boxes. As shown above B is position 1, U is position 2, g is position 3, r is position 4, i is position 5 and z is position 6. You need to insert the filter names of the filters loaded in the PFU in each box. It is strongly recommended that you use the same formatting as used in the PFU (which comes from the bar-coding). So for example if we changed the g for V and r for R filters above, we'd enter the following new names (ignoring the '#' in the PFU names)

      Now you must accept these changes with "Ok", and then exit WFI and then Cicada, and re-start Cicada and then WFI again.

    4.4.3. Start the Telescope Control Task

      Most observers won't need this panel, unless they are guiding.

      Under the "Instrument Controls" pull down you'll find two options. One is AAT_TELESCOPE task. Start this and the telescope control panel will appear. This panel enables you to load co-ordinates, offset and slew the telescope. It is generally not needed unless you are guiding, in which case it is essential (for applying offsets to move guide stars into guide CCDs).

      If you do need to use it, click "Start update". This will regularly poll the telescope for position information (you should see this in the TEL_TASK window you started on aat40a).

    4.4.4. The Message Window
      You don't need to start this one. It will appear as soon as the WFI task starts doing things (like communicating with the controller, changing filters, etc.). You can look in this window for regular updates on what Cicada thinks its doing. One trick to it, however, is that it usually stops updating such that it automatically scrolls to the bottom when a new message appears. So you have to scroll it down with the scroll bar itself.
    4.4.5. The Ximtool Window
      Again, this window should automatically appear as soon as you try to take data. You can make it appear manually with "Tools"->"Show Ximtool" pull down. This Ximtool task is a modified version of the IRAF ximtool task, which deals directly with Cicada to display CCD data as it is read out. You can't use this display for regular IRAF use. In fact if you try to start IRAF from another window when logged in as the same username running CICADA and start another ximtool, the two will often interfere with each other.

      Don't run IRAF with ximtool from the same username as is running Cicada.

      The ximtool window operates in a fairly self explanatory fashion. You can zoom in and out, pan, adjust the grey scale as usual with ximtool. One thing to beware of is that the data values reported by ximtool are only approximate at best, and that the grey scale limits are different in every CCD. So beware, just because one CCD looks darker or lighter than the others, it may not actually be. The grey scale limits could just be screwed up.

    4.4.6. The Exposure Time Counter
      Again, this window should automatically appear as soon as you try to take data. You can make it appear manually with the "Tools"->"Show Counter" pull down.

5. A Tour of the WFI Cicada Interface

Once you've got everything started up, you should have you screen full of windows looking something like this.

Most of the control of WFI operation takes place from the WFI Panel. The major controls are highlighted below.


6. Observing with WFI and Cicada

When observing with WFI on the AAT there are a number of points you should bear in mind

6.1 Looking at your data

It is very important that you not create extra ximtools on the workstation, from the same account as cicada was started from (they get confused and conflicts arise, and you'll end up killing cicada). So to use IRAF to examine your data. (Examining your data from another workstation is not recomended either, as that just means aatssx has to NFS-serve the data accross the network)l.

  1. Move to another workspace by clicking in the CDE control panel.
  2. Start a terminal, and login in the aatssx as wfiobs (not as wfieng) - passwords are on the wall next to the

  3. telnet aatssx
    username: wfiobs
  4. Start an xgterm

  5. xgterm &
  6. Start IRAF

  7. %cl
  8. Start xtimool

  9. !ximtool &
  10. Move to the data directory. For example

  11. cd /wfi_raw1/cicada/20020223/A
  12. Display your data one CCD at a time

  13. imexam 23feb0010[6]
From within imexam you can use 'r' to display radial profiles, seeing fits and aperture photometry (use cl>epar rimexam to change the fitting  and aperture parameters).

Notice that in the example above, we have not used mscexam to display the whole mosaic, but imexam to display a single CCD. Examining the entire mosaic is not recommended, as the large amount of memory this uses can cause resource problems for cicada. We usually use CCD6 for focussing, and single CCD observations.

6.2 In the Afternoon

  1. Go through the Startup procedure above to get WFI ready for observing later at night (including changing filters and updating the WFI filter table if required).
  2. You can have the lights in the dome turned off after 4pm in the afternoon (they must be turned on for visitors to the dome prior to that). You should use the time after 4pm to acquire
    1. bias frames,
    2. dome flats, and
    3. dark frames.

    To acquire domeflats, you need to get the dome rotated to 0 degrees, and the windscreen rotated to 21 degrees. This puts the white patch above the telescope at the zenith (ask the support astronomer or afternoon technician to do this for you). Have the support astronomer or afternoon technician turn off all the lights in the dome. Then go into the dome and check all lights are turned off.

    On a green panel to the far left of the bank of terminals in the control room, is a HPM 2000 VA light dimmer. Turn on the switch below the switch marked "BY PASS" ("BY PASS" bypasses the dimmer, turns the dome flat lamps on full). The dial will now control the brightness of the one of two lamps which can be plugged in to illuminate the dome up at Prime Focus Access. The bright lamp (rather than the desk lamp) can usually be used for dome flats - but you should point the lamp away from the white patch so it is indirectly illuminated.

    Take Test Exposures : Use the Regions Pop-up to select a 100x100 pixel window in the centre of each CCD. Also set the WFI Panel to "Display Only" and set the Exposure Type to "Flat". Now take a 1s exposure, and look at the brightness level of the image. Now adjust the brightness of the  dimmer up or down so that you can get ~30,000 adu in each CCD in 5-10s. (Dome flats shorter than 5s are not really recommended).  Be careful that you don't over-expose the detector. When saturated, the counts "wrap around" to small numbers, and you can get very confused. Always start with 1s exposures and the lamp dim, and then work up to the correct time and dimmer setting.

    Take your Dome Flats : Once you've got the exposure time and dimmer right, turn off the "Display only", put the Regions window back to the Full Mosaic,  set the number of exposures to 5 (or more), and press "Expose".

    Then change to the next filter and repeat.

  3. If you observed last night, check that last night's data has been written to tape correctly. If not, start it writing again when you go to dinner.

6.3 Start of the Night

  1. Twilight Flats : After dinner you need to get ready for twilight flats. You need to be ready to observe on sky for flats by around 30 minutes after sunset in the evening (or before sunrise in the morning). If observing in the U you need to start about 15 minutes earlier (or later).
  2. When the night assistant opens the dome, have them slew to a blank sky field. Then proceed as for dome flats with test exposures (small windows, display only, exposure type=flat). Again aim for exposures of 5s or longer. Remember to turn the Display Only off and the full mosaic on when you are ready proceed after a test. Between each exposure on sky you'll need to increase the exposure time by a factor of about 1.8, and also offset the telescope by about 20s North-South (North-South is recommended so E-W bright star trails are less likely to overlap).

    Keep going through your filters until the sky gets too dark (exposures of longer than 120s are pretty much useless as twilight flats).

  3. Pointing : the night assistant will then want to observe one or more SNAFU stars. These allow us to check the telescope's pointing. The default is to set the AAT's Reference Axis to point stars at the very centre of the mosaic (i.e. the join of the four inner CCDs). We usually then set up Axis A, to point at the middle of the lower half of CCD6.

  4. Use the Reference Axis for survey programs, and Axis A for programs where you want to observe a single object, and make sure it doesn't land on a gap between the CCDs.

  5. Focus the Telescope: After taking flats, and a few pointing checks, it is time to focus the telescope. The focus offsets between the WFI filters are well known. You only need to focus the telescope in one filter. To take a focus frame we manually take a multiple exposure (the WFI focus function does not work at the AAT) around the expected focus value (seven steps of 0.1mm is usually about right).
    1. You can usually focus pretty much anywhere on the sky. WFI usually sees lots of stars in 10s almost anywhere. Set the exposure time to 10s and "Save & Display".
    2. Check the No pre-flush / No readout  radios (each time you press expose now, you open the shutter, but don't readout the detector).
    3. Have the night assistant move the telescope focus to the first value in the sequence.
    4. Press the "Flush" button, and then "Expose".
    5. When the exposure finishes, the night assistant can move the telescope on the sky, and adjust focus to the next value.
    6. Expose again. Goto step 5 as many times as you like (usually putting a double step on the sky before the last exposure)
    7. Finally press Readout. You can then examine the image in the ximtool, or re-display the CCDs one at a time in IRAF to determine the best focus.
    8. Make sure to turn the No pre-flush / No readout radios off for the next normal exposure!

    At the end of the February 2002 run, a script for focussing was created - see below. It has not been tested in anger, but should work.

  1. Start Observing : you're now ready to start observing. You know where your objects will appear on the CCD, and what is the best focus for each filter.
  1. Photometric Standards: We recommend the use of Landolt standards from  Landolt 1992 AJ....104..340L .  (An ASCII version of the catalogue is available here). Many of the fields in this paper can be used to put standards in all the CCDs simultaneously, but they can be a bit on the bright side. The following fields are used by the WFC survey on the INT. These fields may need to be defocused in use at the AAT.
sa92-335   00 55 00  00 44 13 J2000
sa95-330   03 54 31  00 29 05 J2000
sa98-670   06 52 12 -00 19 17 J2000
sa101-427  09 57 26 -00 17 16 J2000
sa104-334  12 42 21 -00 40 28 J2000
sa107-602  15 39 19 -00 15 29 J2000
sa110-361  18 42 45  00 08 04 J2000
sa113-163  21 42 35  00 16 46 J2000
Alternatively, the Landolt list contains a number of fainter sequences clustered into regions of ~5 arcminutes in size, which will fit into one CCD. These can be observed for somewhat longer exposures and with less defocus. Click on the links for finding charts (from the ESO La Silla EMMI calibration plan documentation).
TPhe        00:30:13.5 -46:30:15  J2000
RU149       07:24:15.5 -00:32:02  J2000
RU152       07:29:57.0 -02:05:17  J2000
PG0918+029  09:21:32.0 +02:47:02  J2000
PG1047+003  10:50:10.5 -00:01:15  J2000
PG1323-086  13:25:51.5 -08:50:15  J2000
PG1633+099  16:35:34.0 +09:46:22  J2000
MarkA       20:43:59.0 -10:46:40  J2000
You should not take photometric standards with an exposure time shorter than 5s, otherwise your photometry will be compromised by atmospheric scintillation.

6.4 In the Morning

In the morning you should reverse the twilight flat procedures from the evening.

If you didn't get all the bias frames or darks you needed you can start these running before you go to bed.

And finally, you should start writing last night's data. If you started some darks running, you can put the tape saving operation to sleep, so it will start after the data taking is finished.

7. Using prepared scripts

It is possible to chain together WFI operations (including telescope offsets, telescope focus, changes in exposure time, type, etc.) by creating script files which Cicada can execute.

Unfortunately, these must be written in TCL, which is the worst programming language I've ever used (Microsoft BASIC on my TRS-80 was more convenient). Its a complete dog.

So that astronomers don't have to learn how to use TCL, we have tried to prepare a few pre-packaged scripts which can be straightforwardly modified to fulfil most observing requirements. These scripts are stored in /home/aatssx/wfieng in read only format. You should copy a script you'd like to use to a new name, make it writable, and then edit it.

AAO_offset.tcl    - a script to take an imaging data sequence, with offsetting and focussing.
AAO_std.tcl       - a script to take observations in multiple filters of std stars
AAO_linearity.tcl - a script to take a sequence of data for doing linearity and shutter timing calibrations.
So to work with AAO_offset.tcl
cd /home/aatssx/wfieng
cp AAO_offset.tcl YOURNAME_offset.tcl
chmod +w YOURNAME_offset.tcl
nedit YOURNAME_offset.tcl (or whatever your favourite editor is)
When happy with your script, start it using the "Actions"->"Run Cicada Script ..." to select a script to run, or "Actions"->"Run last scipt" to re-run the last script you ran. There are accelerator buttons for both of these.

The left one starts the file chooser to select a script. The right one runs the last script again.

7.1 AAO_offset.tcl

This script can be used to control telescope movements, filter changes and focus changes, to create an observing sequence.

You can look at a copy of the script file itself (as of 24 Feb 2002) at AAO_offset.tcl to get a feel for what it looks like. However, the version in use at the telescope may have been updated, so bear that in mind. As described above,  you chould copy this file to your own version, chmod it to make it writable, then edit it. There are seven (7) locations you need to change.

# (1) !!!***!!!  Set number of exposures and exposure times.
   set times  { 10 20 30 }
Enter as many  exposure times between the braces, as you want exposures. In the above example the script will take 3 exposures.
# (2) !!!***!!!  Set offsets for each exposure
   set offra  { 0 r5  12 0 0 0 0 0 0 0}
   set offdec { 0 r10 r5 0 0 0 0 0 0}
Enter an ra and a dec offset for each exposure in arcseconds of polar axis rotation. You must take account of cos)dec) effects your self at the moment. If an entry is in the format rNNN, then the script will compute a random offset in a range -NNN to +NNN.
# (3) !!!***!!!  Set filter for each exposure
   set filter { 2 1 3    }
Enter a filter for each exposure - these must be the filter positions in the wheel. Cicada has no way to specify these as filter names.
# (4) !!!***!!!  Select type of offset.
# Uncomment this to offset cumulatively
#   set offstr "OFFSET"
#   set fitsk3 "CUMULATIVE OFFSET"
# Uncomment this to offset from the position the telescope last slewed to.
   set offstr "OFFSET/SL/WAIT"
   set fitsk3 "OFFSET FROM BASE"
Choose a way of specifying the offsets - either as cumulative from the last exposure, or offset from the base slew position.
# (5) !!!***!!!  Setup focus base for this run.
#  Absolute V focus measured 9-13 August 2001).
#   set vfocus 39.65
#  Absolute V focus measured 14 Feb 2002 ).
   set vfocus 39.15
# (6) !!!***!!!  Setup focus offsets for the loaded filters.
   set focoff { 0.65 0.65 0.0 0.0 0.25 0.15 }
Focus values are specified as a base focus for the V filter, and an offset for each filter. At the start of each run, the base focus will be measured. Then you need to put the correct offsets in $focoff for each filter wheel position. (Focus offsets for each filter can be found on the WFI Performance page).
# (7) !!!***!!!  Select Window.
# Uncomment for Full Mosaic
#   set window "DO_SAVE=1 REG_WINDOW=\"REG_1x1_8422x8282+0+0\" XO=0 YO=0 WIDTH=8422 HEIGHT=8282 NREGIONS=1 CCDMASK=65535 CAMERA_COORDS=1 RCF=1 CCF=1"
# Uncomment for Full Mosaic Binned by 2
   set window "DO_SAVE=1 REG_WINDOW=\"REG_2x2_8422x8282+0+0\" XO=0 YO=0 WIDTH=8422 HEIGHT=8282 NREGIONS=1 CCDMASK=65535 CAMERA_COORDS=1 RCF=2 CCF=2"
# Uncomment for single CCD6 (unbinned) only
# Uncomment for testing - small windows, no save.
#   set window "DO_SAVE=0 REG_WINDOW=\"REG_CEN_CCD_1x1_512\" XO=793 YO=1812 WIDTH=512 HEIGHT=512 NREGIONS=1 CCDMASK=255 CAMERA_COORDS=0 RCF=1 CCF=1"
Choose between the window options by uncommenting a single line. These should cover most of the likely windows you'd want to use for real observing. The last option is a small window, which is not saved to disk. Use this to test that your script works!

After changing all of these to the values you'll wnat bto use, you are stongly recommended to test your script out in the afternoon or evening before you start observing (do this by selecting the test window above, and some short exposure times). Then look at the Cicada Message window to check it is doing what you think you wnat it to do.

7.2 AAO_std.tcl

This is basically just the AAO_offset.tcl script, set up for doing short observations in BUVRiz. Experience may indicate that its worth defocussing some of the 'inner filters' (V,r,i) by 0.2-0.4 mm to avoid saturation - you can change your script to do this, of course.

You can also create a script to put the same std in every CCD. Just insert the appropriate ra/dec offsets for the declination
# dec=0
set offra = { -475.2  -475.2  -475.2  -475.2   475.2   475.2   475.2   475.2 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }
# dec=-20
set offra = { -503.7  -503.7  -503.7  -503.7   503.7   503.7   503.7   503.7 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }
# dec=-40
set offra = { -622.5  -622.5  -622.5  -622.5   622.5   622.5   622.5   622.5 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }
# dec=-60
set offra = { -950.4  -950.4  -950.4  -950.4   950.4   950.4   950.4   950.4 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }
# dec=-70
set offra = {-1387.6 -1387.6 -1387.6 -1387.6  1387.6  1387.6  1387.6  1387.6 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }
# dec=-80
set offra = {-2737.2 -2737.2 -2737.2 -2737.2  2737.2  2737.2  2737.2  2737.2 }
set offdec= { -726.7  -242.2   242.2   726.7  -726.7  -242.2   242.2   726.7 }

7.3 AAO_linearity.tcl (also use this to get data to check shutter timing)

You can look at a copy of the script file itself (as of 24 Feb 2002) at AAO_linearity.tcl to get a feel for what it looks like. However, the version in use at the telescope may have been updated, so bear that in mind.

This script is easy to use - decide whether you want to look at linearity (ie high count rates) or shutter timing (low count rates), and uncomment the relevant lines.

# This is the list of exposure times IN MILLISECONDS
# which will be performed. Choose between them for linearity or shutter timing.
# Linearity
set times { 0 0 0 0 0 10000 10000 10000 5000 7000 9000 10000 12000 \
            15000 18000 10000 20000 24000 28000 10000 30000 35000 38000 \
            10000 43000 47000 48000 10000 50000 53000 10000 58000 10000 \
            65000 70000 10000 10000 10000 0 0 0 0 0 }
# Shutter timing.
#set times { 0 0 0 0 0 10000 10000 10000 5000 7000 9000 10000 3000 \
#            2000 1000 10000 700 500 400 10000 300 200 100 10000 80 \
#            70 60 50 10000 10000 10000 0 0 0 }
Then set up as follows
  1. Point the telescope at the domeflat screen (get the night assistant, afternoon technican or support astronomer to do trhis for you) and open the mirror covers and prime focus dust cover.
  2. Turn on the domeflat lamp
  3. Set the FILTER wheel to the filter of choice (gVRr are good for this) and adjust the flat field lamp, to give around 13,000 adu in10s, and around 50,000 in 50s.
Execute the script from AAO_linearity.tcl "Actions"->"Run Cicada Script...".

The data acquired can be calibrated as a function of time using the 10s exposures, and then you can examine the adu per unit exposure time to determine the detector's linearity.

7.4 AAO_focus.tcl

This script controls the acquisition of a focus sequence. The parameters you need to provide are
# (1) !!!***!!!  Set exposure time for each image.
   set times  10
# (2) !!!***!!!  Set offsets on sky in arcsec & rough declination.
#                Suggest offset should be > 10
   set offsky  15
   set dec     -30
# (3) !!!***!!!  Set focus start, step, and number of exposures
#                7 steps at 0.1 spacing should work well.
   set focnexpo 7
   set focstart 39.15
   set focstep  0.1

The data file created will have focnexpo images, in a sequence staring from focus value focstart, with focus step focstep and spacing on the sky of offsky arcseconds (assuming you've put the declination in correctly!). The sequence will appear vertically on the display, with the first focus value first (and a double spatial step at the end). The script calculates the spacing in pixels as it will appear in the mosaic and puts all this information into the header (FITS keywords FOCNEXPO, FOCSTART, FOCSTEP, FOCSHIFT).

In principle this script should create images which can be processed by the IRAF task mscfocus. The first image should be at the 'top' of  a sequence, and the gap should be at the bottom. You should be able to use mscfocus to select the top image, and it will find the rest, fit to them and plot up FWHM information. MSCFOCUS may not expect a gap at the end (I can't tell because the NOAO Mosaic documentation is silent on exactly what the telescope does),  in which case the code to put a double step at the end should be removed.

8. Writing scripts

You have to write these in TCL. It sucks. Big time.

You can use the scripts above as examples, and should consult the relevant section of the RSAA CICADA Users Manual.

9. Guiding

Auto-guiding with WFI is performed using signals from eight dedicated guider CCDs mounted at the periphery of the WFI mosaic (see the layout plot). These CCDs are TI ???? ???x??? ??um pixel devices, connected via a multiplexer constructed by RSAA, to a standard commercial SBIG CCD controller. The multiplexer selects which of the 8 guider CCDs is connected to the SBIG controller. (Guide CCD3 is inoperable). Data is acquired from the SBIG controller into a dedicated PC mounted at the prime focus, running the commercial MaximDL software package for imaging and guiding. (Only the guiding functions need concern us).

The display  of this PC is mirrored via a "VNC viewer" protocol over the AAT's ethernet, to another PC in the control room (labelled the "WFI Autoguider Control" PC). This link is functionally quite slow, so don't go wild with mouse motions.

It is almost always necessary to adjust the telescope pointing slightly so that a guide star will appear in a guide CCD. This can he done with the GSFIND and AAT_TELESCOPE tasks of Cicada.

In the sections that follow we first discuss whether you need to guide, then describe the MaximDL software, and the GSFIND/AAT_TELESCOPE tasks. And finally, we provide a step-by-step guide to guiding.

9.1 Should I guide?

The overheads involved in guiding are significant - at least 2 minutes per telescope pointing to acquire a guide star and start guiding on target. Moreover, the AAT tracks perfectly adequately for imaging observations in all but the most exceptional seeing for up to 10 minutes. Certainly for 5 minutes. And in all passbands except U or narrow-bands, 5 minute observations are sky-limited.

So there is no read-noise penalty in combining unguided 5 minute exposures. In fact, at R, i and z, many observers won't be able to exposure for longer than 450-600s anyway (especially if observing binned) since that's the time for the sky to reach near half-well depth.

You can also only guide (easily) with the telescope in the Reference Axis, so that GSFIND can understand the telescope co-ordinates.

The bottom line is that, except for U or narrow-band observing, there is no need to guide, and the overheads and pain guiding adds is not worthwhile.

9.2 The Multiplexer & MaximDL Software

Getting started.

A window should then appear - you are looking at the windows desktop for the guider PC at prime focus.  There are two icons you need to click on (if the programs are not already running) are
the Multiplexer selector "WFI Guider Selector"
and "Maxim DL" .


The only thing you can do in this window is select which of the guide CCD the SBIG controller talks to. There are two ways to do this. There is a pull down menu, and a graphical interface.

Maxim DL

Maxim DL is a commercial package primarily designed so that amateur astronomers can both take imaging data, and guide their telescopes. There is a large panel in which images are displayed, a small window showing the histogram of pixel values, and the small Maxim CCD control window.

We only want to use it to guide our telescope, so the only tabs in the Maxim CCD window you need to use at all are "Setup" and "Guide".

As shown above, the Setup panel should be used to tell MaximDL that both the CCD and Guider are controlled by SBIG ST-5C controller. This should already be the case, when you start, if not set both tabs to this value.

The Maxim software has no knowledge of how the AAT works (i.e. how X-Y on the image corresponds to ra,dec or the relevant scales). It simply sends signals to relays, which pretend they are using a guiding paddle to guide the AAT. So at the start of each night, you need to "calibrate" the guider (i.e. work out all the above parameters).  MaximDL does using its Calibrate function - if you put a star down a CCD and select Calibrate, the press Start. MaximDL will drive the AAT, and work out which directions are N-S-E-W etc., and what the appropriate scale factors are. Make sure you put in what the declination was for the calibration. You only need to do this once per run.

You can use this tab to either take individual exposures (for acquisition) when the Expose radio is selected, perform the calibration (when Calibrate is selected), or you can guide (when Track is selected). In each case you start by pressing the Start button (and can then stop guiding by pressing the Stop button). The exposure time used for each is set by the Exposure. You also need to set the Declination, when Guiding so the appropriate Cos(dec) factor can be applied.

The X,Y boxes show the location at which MaximDL will attempt to guide in the guider CCD image. You can select this by clicking on the the guider CCD image, or use the Auto button. The Settings button brings up further guiding settings. You need to make sure these are set as shown below - especially the Binning=2. The Manual Calibration shown shown should be a reasonable guess to the parameters you'll measure from your actual calibration). Note that these Manual Calibration settings assume the night assistant has loaded a guiding rate of 1"/second into the AAT TCS.

9.3 GSFIND and the AAT_TELESCOPE task


Start GSFIND using "Tools"->"Start GSFIND". Then it is usually most convenient to move this window to another workspace using the "Occupy Workspace" function of the window manager.

Start AAT_TELSCOPE using "Instruments"->"AAT_TELESCOPE". This has to stay in the same workspace as cicada. When it appears press the "Start update" button.


The AAT_TELESCOPE panel has been discussed a little earlier.

It provides a graphical interface for sending commands to the telescope (via the TEL_TASK). It is very important that this task, GSFIND and the AAT all have their co-ordinates in the same equinox. Check the TEL_TASK window on the X-terminal. The lines of positions should indicate whether the data is in 1950.0 or 2000.0 equinox.

Then use "File"->"Preferences" in the Telescope Control window (left) to set this task's equinox to B1950.0 or J2000.0.

Finally you must use the radio buttons in GSFIND to set its co-ordinates to B1950.0 or J2000.0 (see below). All three can be one or the other, but they must all be the same.



Once the AAT_TELESCOPE task is updating, the GSFIND task can be used. Before you do anything, make sure the equinox GSFIND is working in is the same as that used by the TEL_TASK and AAT_TELESCOPE (above). You can use the radios to choose between B1950.0 and J2000.0. Then, if you click on the  button, GSFIND will load the current telescope co-ordinates, and display the GSC stars present in the region of the sky where WFI is currently pointed.

You can select the magnitude ranges in which GSFIND display targets, whether it displays galaxies, whether it displays a circle at the field centre.

You can also grab the WFI mosaic outline in the window and drag it around until a guide star lies in one of the CCDs. After which you'll see something like the image below. Notice the WFI mosaic is no longer centred on the original field centre (marked with the red cross hairs), and that the Field and Detector co-ordinates are now different.

Now if you go back to the AAT_TELESCOPE Telescope Control task, and click on "From GSFIND" the new mosaic co-ordinates will be loaded into the co-ordinates window of the panel, and highlighted.

Now if you press "Track" the telescope will be moved to the new co-ordinates, and you should be able to open the shutter and detect the guide star in the indicated guide CCD.

9.4 Guiding - Step-by-Step

  1. Have the night assistant load a guide star rate of 1"/second into the AAT TCS.
  2. At the start of the night either perform a guider calibration, or check that the manual calibration numbers above perform adequately.
  3. Make sure the TEL_TASK, AAT_TELESCOPE and GSFIND tasks all provide/expect co-ordinates in the same equinox.
  4. Slew the telescope to your next target.
  5. Make sure the AAT_TELESCOPE task has the current telescope position (i.e. its updating).
  6. Use the  button to load the AAT_TELESCOPE co-ordinates into GSFIND and display the available guide stars.
  7. Drag the field around until a guide star is in a CCD.
  8. Use the "From GSFIND" button in AAT_TELESCOPE to get the new mosaic co-ordinates, and select them.
  9. Use the "Track" button in AAT_TELESCOPE to move the telescope to the new co-ordinates.
  10. Use the Guide Star Selector on the PC to select the correct guide CCD.
  11. Open the PFU shutter.
  12. Select 'Expose' and press 'Start' to take a test exposure to ensure you can see the guide star, and select an appropriate exposure time.
  13. Select the guider pixel position, using 'Auto' or by selecting a pixel in the image display.
  14. Select 'Guide' and press 'Start' to start guiding and ensure guiding is working.
  15. Once satisfied guiding has successfully started, press 'Stop', and close the PFU shutter.
  16. Now start your exposure. Once the PFU shutter has re-opened, start guiding again. While MaximDL should recognize when the star vanishes and stop guiding, sometimes this doesn't work. If taking more than one exposure at the one guiding position, it is recommended you stop guiding when the shutter is closed.

10. Saving your data

It is your responsibility to make your own copies of all your WFI data.

WFI data files are large, so they can currently only be stored on tape. Although the Observatory will archive all WFI data onto tape and retain copies at the AAT, requests to extract data from the archive by observers who haven't bothered to make their own copies are not likely to be processed particularly rapidly.

Writing data to tape takes up a significant quantity of the aatssx resources. Do not write data and attempt to observe at the same time. You should aim to start your data tapes writing at the end of each night before you go to bed.

10.1 Formats

Data can be saved in many formats, but only four that are really viable.
  1. DLT4000 (Digital Linear Tape)
  2. DLT7000 (Digital Linear Tape)
  3. DDS4 (Digital Data Storage) version 4
  4. DDS3 (Digital Data Storage) version 3
All of the above formats allow for compression. In principle, compression can result in up to a factor of two improvement in tape storage. In practise, imaging data does not compress at all well, and you will get at most a factor of 1.3-1.5 improvement. Given the overheads, compression is usually not worth it.

Smaller tape formats like DDS2 or CDROM are not useful. You can only fit 5 WFI images on a CDROM!

10.2 Drives

You should find out what types of drives you have available to read your data at home. DDS drives are all downwards compatible (i.e. DDS4 drives read 2,3 & 4 tapes, DDS3 read 2&3). DLT7000 tapes can only be read on a DLT7000 drive.

You should save your data to tape using the drives on aatssx. Using any of the other drives on other machines will just grind the entire network to a halt. The drives available are

10.3 Writing a tape

To write your data as a single tar save set for a single night's data
cd /wfi_raw1/cicada     (or wherever your night's data is wfi_raw2,wfi_data1 etc.)
setenv TAPE /dev/rmt/1n    (or whichever of the drives above you wish to use)
tar cv 20020220       (or whatever your night's data directory is)
To check it has been written OK
mt rew
tar tv
To rewind and eject your tape
mt rewoffl

10.4 Writing more data to a tape which already has data on it.

If you want to write data on the same tape you have already written data to, you need to forward space past the end of the already written data. Be very careful here. You can overwrite previously written data.

Suppose you have already saved one nights data as a tar save set. You need to space forward by one file, and then write tonight's data.

cd /wfi_raw1/cicada     (or wherever your night's data is wfi_raw2,wfi_data1 etc.)
setenv TAPE /dev/rmt/1n    (or whichever of the drives above you wish to use)
mt fsf 1
tar cv 20020220       (or whatever your night's data directory is)
If you'd already written two save sets, you'd have used mt fsf 2, and so on.

10.5 Delaying a tape write until observations have finished.

If you still have some observations running when you leave the dome in the morning, you can delay the tape writing until all your exposures are done, as follows.
cd /wfi_raw1/cicada     (or wherever your night's data is wfi_raw2,wfi_data1 etc.)
setenv TAPE /dev/rmt/1n     (or whichever of the drives above you wish to use)
sleep 3600 ; tar cv 20020220  (where the sleep command waits for the indicated number of seconds)

10.6 Tape charges

All observers will be required to pay for tapes used before they leave the mountain.

11.Things that go wrong ...

Things that go wrong when I try to start Cicada/WFI

Unfortunately, this one is not as rare as we'd like. Usual problems are

Filter task failure
This is not a disaster, and usually means you haven't started the PFU task. Try starting it, and then using the AAT FILTER TASK to move the filter wheel. If this works the problem is fixed.

If this doesn't fix it, then you probably have a serial link problem between aatssx and aatpfu. Get your support astronomer or afternoon technician to help here.

Failure to communicate with controllers
If you've had a failure of an image read, it is quite common to not be able to re-establish communication with the controllers after killing Cicada and re-starting it. You need to reedit WFI, then Cicada, use cicada_cleanup, and start again. Please use patience here. It often takes several iterations. It may help to do the cleanup, start cicada, and then exit it without trying WFI, the cleanup again, start Cicada and then start WFI (anecdotally I have seen this help a few times).

Failure to communicate with ximtool
If you've had a failure of an image read & display, it is quite common to not be able to re-establish communication with the ximtool task after killing Cicada, and ximtool and re-starting it. You need to re-exit WFI, then Cicada, use cicada_cleanup, and start again. Please use patience here. It often takes several iterations. It may help to do the cleanup, start cicada, and then exit it without trying WFI, the cleanup again, start Cicada and then start WFI (anecdotally I have seen this help a few times). When trying to see whether communication with ximtool has re-started it will help to put in some tiny windows, and use "Display Only".

Failure to communicate (via the serial link) with the PFU.
See below for how to flush the serial link.

Things that go wrong when I try to take data

Readout of the mosaic does not complete
Communication with ximtool is lost

Both of these will usually result in nasty big red error boxes appearing. Unfortunately, both are not as uncommon as we'd like. In many cases, there will be no obvious cause for the problem, and your only fix will be to exit Cicada and restart. Sometime these problems do have causes. The most likely causes are

Things that go wrong when WFI talks to the telescope

Occasionally the WFI_TEL_CONTROL task which runs on the VAX and sends commands back and forth between Cicada and the AAT TCS will die .... usually with error messages indicating that the VAX's access has been violated.

This is easy to fix. On the x-terminal where the WFI_TEL_CONTROL task was running (and all the error message now are) simply type
40a> wfi_tel_control

Then on aatssx, you need to flush the serial link between aatssx and the VAX, which is currently hung. To do this type
[wfieng]/home/aatssx/wfgieng: echo WHERE > /dev/ttya
After doing  this you whould see a 'WHERE' command and the telescope's repsonse to it on the xterminal where wfi_tel_control is running. Hey presto you are back in business.

Things that go wrong with PFU

The filters don't get read properly when I initialise the filter wheel.
Sometimes the "Initialise Filter" "Read Filter" will fail to read one or more bar codes when the telescope is at prime focus access. Ask the support astronomer, afternoon technician or night assistant to move the telescope to the zenith and repeat the Initialise Filter (followed by the Read Filter).

When I try to move to a new filter the filter wheel fails to complete the move
PFU's filter wheel has proved to be remarkably robust. We've only come across two reasons why a filter move has failed

  1. The building gas pressure, which operates the pneumatic detents on the filter wheel, is too low. This is the most common problem. If a wheel move fails this will almost always be the problem. See your support astronomer, night assistant or afternoon technician for help.
  2. The filter is too thick (or the screws holding it in project above filter holder) and the wheel scrapes or jams. This is a mechanical problem that you can only diagnose by trying to manually move the filter wheel while the telescope is at prime focus access.
The serial link between aatssx and PFU does not seem to work.
Occasionally (as with the telescope serial link) the serial buffer on aatssx will get jammed. This can be flushed by using the following command at a unix prompt on aatssx
[wfieng]/home/aatssx/wfgieng: echo 'F?' > /dev/ttyb
After doing this a F? should appear on the PFU loggin window, in response to which the PFU should send back the location of the filter wheel to aatssx.

Things that go wrong with the focal plane temperature

The booster heater power supply is not working
A small booster power supply for the heater (on the left side of WFI) is required to raise the focal plane temperature from liquid nitrogen temperature to 183K (the mosaic is operated so warm because of the poor serial charge transfer efficiency of two of the CCDs). Sometimes the power cable on this power supply comes loose. Remove the cable and re-seat it.

12. Frequently Made Mistakes

13. Frequently Asked Questions



Appendix - Twilight Flat positions

The following table is of blank fields used at the European Southern Observatory, La Silla. Observers with new blank fields they would like to make available are asked to e-mail details to Chris Tinney.

But be careful - some of these blank fields are blank because they are the centres of dark clouds - so they are often not that blank in i or z, and with a field as large as WFI you often see lots of stars around the dark clouds.

Field RA(1950)
 h  m  s
  d  m  s
SGP 00:48:30.3 -28:03:01 Contains ~ 10 objects in 6.4' x 6.4'
0102-265 01:02:48.5 -26:34:25 Contains ~ 15 objects in 6.4' x 6.4'
0248-196 02:47:46.6 -19:46:11  
0427-36 04:27:26.1 -36:25:16 ok - 5' x 5'
9090-7 09:09:32.6 -07:38:26  
CT1 10:04:27.0 -02:19:00  
1101-264 11:02:23.5 -26:43:57  
CT5 12:26:08.7 -06:38:29  
CT2 12:54:58.7 -02:07:04  
SER1 15:13:13.9 -00:31:48  
2335-40 23:34:34.6 -39:49:04  
2345+007 23:45:45.9 +00:40:40  
SPKS 01 12:28:04.0 -07:46:54 A bright star in the field
SPKS 02 11:07:06.0 -77:05:54  
SPKS 03 12:28:38.0 -63:28:18  Not that blank
SPKS 04 15:39:43.0 -33:56:54 No stars in 5' x 5' Few in 8'x16'
SPKS 05 16:02:43.0 -45:48:18 Few stars in 5' x 5'
SPKS 06 16:25:40.0 -25:09:48 Few stars in 5' x 5'
SPKS 07 17:07:47.0 -40:34:06  
SPKS 08 17:31:06.0 -25:44:24  
SPKS 09 18:02:01.0 -04:32:36  
SPKS 10 19:00:48.0 -37:21:18  
SPKS 11 13:04:33.0 +29:50:49  
SPKS 12 16:49:42.0 -15:21:00 No stars
SPKS 13 19:19:09.0 +12:22:05  
SPKS 14 21:26:54.4 -08:51:41  
  10:55:49.7 -77:08:36  

Appendix - Other bits of Cicada you might find useful

Cicada is a large piece of code and very complex. For full details on all its functionality consult the RSAA Cicada documentation. However here's a few odds and ends we've found we use.

GIT - "Tools"->"Start GIT"

GIT is the Graphical Image Tool. You can use it to display images, and do various things. I have always found it to be slow, cumbersome and useless. It also uses up a lot of resources.
"Options"->"Preferences" "Options"->"Hardware Configurations ..." "Options"->"Exposure Time Unit"
Cicada exposure times must be integers. You can do exposures shorter than 1s by setting the exposure time unit to milliseconds (abbreviated by Cicada as "msec" - obviously a new non-SI unit of time). In general use, leave the exposure unit as seconds.
"Options"->"Show xxx"
Pop-up the Regions, Messages, Counter and FITS Keyword windows.
"SDSU"->"Readout Mode"->"FAST"
WFI is only setup to operate in the FAST speed. Do not change this from FAST.
"SDSU"->"Show temperatures"
Pop-up the temperatures window, from which you can control the WFI focal plane temperature. DO not change any of the parameters here.
"SDSU"->all the other options
Should not be used by WFI observers!

    This document written by Chris Tinney 19 February 2002 onwards.