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Operating the Graphical User Interface for UCLES

In April 2005, the new AAO-2 Optical Detector Controllers (ODC), and their associated Graphical User Interface (GUI), were commissioned for use with the MITLL3 and EEV2 CCDs used on the Coudé échelle spectrographs. Since early 2006, the spectrographs themselves are now configured and controlled within the one GUI. This document gives an overview of their operation, and some suggestions should things go wrong.


Startup, Shutdown, and Problems

The ODC and UCLES Interface

Starting up the GUI

The graphical user interface (GUI) for UCLES and its associated Real Time Display (RTD) can be run up on almost any X11-compliant display. However, they are best run from the one of the twin-headed consoles in the control room. Their login screen enables them to be used as the console for either one of the general purpose PCs in the control room (aatlxa or aatlxb), or one of the rack-mounted instrument control PCs behind the partition ( aatlxx or aatlxy). In general, aatlxx is reserved for UCLES/UHRF, and aatlxy for 2dF/AAOmega, but the two are interchangeable (albeit with separate home directories for the aatinst account). Check the whiteboard in the Control Room to see which machine you should be running on.

  1. If the GUI is still running from the previous night, it should not be necessary to re-start it from scratch. From the AAO CCD Loader, select Commands -> Reconfigure, and check that the UT date, file names, directories, and run number are appropriate (see below). Then click "OK", and away you go.

  2. Otherwise, you will need to restart the GUI from a terminal window, while logged in to the Linux system aatlxx as aatinst. If you're not sure this is the case, then exit from the current Desktop session. Before logging in, you will be asked which host you wish to connect to - select the icon marked aatlxx. The twin-headed monitor will now serve as the console for aatlxx, rather than aatlxb. Login as aatinst (ask AAO Staff for the password).

  3. Opening a terminal window on aatlxx should give the ">" prompt for the aatinst account. The startup command will depend on which VME system the CCD controller is connected to, and which of its two inputs (0 or 1) the orange fibre-optic link (FOL) cables are plugged into. Each VME system can talk to two CCDs controllers simultaneously, through separate interfaces. The whiteboard in the Control Room should indicate which interface is currently in use. Usually this will be /fol1 on aatvme15, and the startup command will be ucles2. Occasionally it may be necessary to run from the spare ODC system aatvme6, (in which case you should use ucles2 swap) or from /fol0 (use ucles1) instead. For more information and options, see Tony Farrell's software guide.

  4. After logging in as aatinst, type the following commands into this window:

    > cd                           (you must run the GUI from the aatinst home area)
    > ucles2            (if using the default controller interface on aatvme14), or
    > ucles1 swap      (if using /fol0 on aatvme10), etc.

    This will establish a number of processes running on various sub-systems, verify the position of each of the spectrograph elements, and bring up the various control GUIs on the workspace. These include the AAO CCD Loader, the Optical Detector User Interface, the Skycat RTD, and lastly the System Configuration window (shown below). This selects the instrument, the data/dummy directories and file root name by default, and allows you to specify the first run number (allowing you to overwrite existing files if you really want to). Check that it all looks right, then select "OK".

    System Configuration

  5. Although Skycat is the default RTD, the related Gaia tool provides expanded functionality as described below. If you would prefer this as your RTD, then simply exit from Skycat, and in the terminal you started up the GUI in, type

    > gaia &

    to bring up a new RTD, which will automatically connect to the data acquisition system. The RTD can be iconised, and it will pop open whenever a new readout commences if you select AAO-Detectors -> Auto Raise on new image. If you would like the RTD to update less/more often during readout, go to Commands -> Set slice size in the ODC User Interface and choose the number of rows to be read out before refreshing the display.

  6. Just as with IRIS2 and 2dF, the Portable Telescope Control System (PTCS) must also be running. This is started automatically (if not already running) by the ODC system, but will not launch the PTCS GUI. If you would like to have this GUI available (e.g. for commanding offsets, or simply to see what the UT or airmass is), then telnet to aatptcs as aatinst, then type

    > tel

    to launch the PTCS GUI

Problems with start up

If the UCLES + ODC system does not come up properly, there is a hierarchy of fixes:

  1. Are you trying to start it from somewhere other than the aatinst home area?
  2. Is the PTCS display updating? It may need restarting - consult your night assistant or afternoon shift technician.
  3. Reset the GUI tasks - first as a SOFT reset, and then as a HARD reset if that doesn't work.
  4. Reset the VME system.
  5. Kill the UCLES + ODC Interface and start it again.
  6. Kill the UCLES + ODC Interface, manually reset the ODC hardware and start it again.

If none of the above work, please contact your Afternoon Shift Technician or Support Astronomer for assistance.

The procedure for each of these steps (in turn) is:

Reset the GUI tasks

  1. Find the AAO CCD Loader GUI on the display from which the UCLES + ODC Interface is being run.
  2. Select Commands->Reset
  3. A pop-up will appear and ask what type of reset to perform ('soft' or 'hard'). Try a soft reset first.
    • The AAO CCD Loader will reset all its tasks, and re-establish connections with all the other computers it needs to talk to. Eventually the System Configuration GUI (shown above) will appear. Update it if necessary and click "OK". If you are presented with a succession of error dialog boxes instead, then you will need to go to the following section.
    • Try a test exposure.
  4. If the soft reset doesn't work, repeat from step 2 above, but this time do a hard reset.

Reset the VME system

If the above does not work, the VME machine (usually aatvme15, but possibly aatvme6 if running the spare system) which interfaces between the CCD controller, and aatlxx may need to be reset. This can be done by selecting Commands -> Reset VME System from the AAO CCD Loader (or if this GUI is unresponsive, by pressing the marked Reset button on aatvme15 / aatvme6 behind the Control Room partition).

Kill the UCLES + ODC Interface and start it again

  1. Find the aatlxx window from which you started the ODC interface.
  2. In this window type "cleanup". You'll get a long string of messages about things being killed, removed, or otherwise expunged.
  3. Restart the GUI as though starting it from scratch, using the instructions above (i.e., "cd" then "ucles2", etc. on aatlxx).
  4. If everything comes back up, take a test exposure to check everything is working.

Kill the UCLES + ODC Interface, manually reset the ODC hardware, and start it again

If all the above doesn't work, you may need to manually reset some hardware. It's time to ask for help from your Support Astronomer or Afternoon Technician.

At the end of the night

You can leave all the GUI running at the end of the night. You will get a warning pop-up at 10am AEST that the UT date has changed, to remind you to do a Reconfigure before observing each afternoon.

The ODC and UCLES Interface

Once the GUI is up and running, you should have four displays visible on the desktop:

AAO CCD Loader

This shows the status of various GUI sub-systems (e.g. the UMIT task which gets the instrument configuration from UCLES, the DRT task which records the observations, etc.). These are all green when the GUI is running correctly. Below this is a Messages sub-window which will alert you to any problems by highlighting them in red. There is an "Exit" option in the "File" menu, which is the recommended way to shutdown the system if necessary; when prompted, select Local Systems to run the cleanup procedure on.

CCD Loader

The Reset option under Commands will do a full reset of all tasks, and bring up the System Configuration window again.

The Reconfigure option will just bring up the System Configuration window again. You should do this at the start of each night to ensure the filename dates and directories have the correct UT date, or if you really wish to overwrite existing data files by setting the First Run Number accordingly (note that the Night Assistant will need to delete runs to be overwritten from their archive log, so be sure to warn them of what you are doing).

Optical Detector User Interface

This is the main configuration and control system for the ODC and for UCLES. It is divided up into two halves: the left half contains 2 tabbed displays, one for configuring exposures and the other for configuring UCLES itself. Click on the "Detector" or "Ucles" tabs at the top left to switch between these two displays. The right half shows the CCD status and sequence control, and is visible regardless of whether the Detector or Ucles tab is currently selected. The UCLES control tab is discussed further down, but let's start with a closer look at each of the ODC-related sections:

Detector Setup

Defines the observation parameters, and detector readout windows.

Detector Setup

Next Run: After each exposure completes, the "Next Run" field updates with the next observation number to be written. During an exposure, this field changes to Current Run (e.g. "Glance", "Dummy m", "Run 5"). If you wish to overwrite existing data, you will need to reset the Next Run number using Commands -> Reconfigure in the AAO CCD Loader.

Total Number of Runs: If several identical consecutive exposures are required, the total number of images required can be entered into this field, before starting the first exposure. The number of frames remaining to be taken will be decremented in the Repeats field of the CCD_2 Status (or CCD_1 status if using the second controller interface) section, and in the Repeats Left field of the CCD Run Control section as each one is taken. The field itself will be greyed out until all repeats are completed, after which it will reset itself back to 1. If you wish to change the number of repeats, or the exposure time of each during the sequence, you can do this from the CCD Run Control section. Checking the "nonstop" box will cause exposures to continue indefinitely, until terminated either by unchecking the box, or by clicking "Stop Repeats" in the CCD Run Control section.

Recording: There are three types of observation:

Exposure Time: Enter the desired exposure time here before starting an exposure. It will be greyed out while the run is in progress, but if you decide to extend the exposure time (and readout has not yet begun), or shorten it, this can be done from the CCD Run Control section.

Readout Speed: Select the desired readout speed, bearing in mind the trade-offs between readout time, read noise, gain, linearity, etc. given by the table of AAO-2 controller perfomance.

Object: Enter the object name here before starting an exposure. It will be greyed out while the run is in progress, but if you decide you need to correct it before readout has completed, this can be done from the CCD Run Control section.

Comment: Enter a comment here before starting an exposure, to be added to the FITS header. It will be greyed out while the run is in progress, but if you decide you need to insert a comment before readout has completed, this can be done from the CCD Run Control section.

CCD Windows: This section allows the observer to load existing CCD readout window definition files, or create and store new ones. Y defines the number of CCD rows to read out, with binning if appropriate. X1 usually defines the CCD columns which make up the data section. X2 usually defines the (virtual) CCD columns which correspond to the Overscan section. Previously-defined CCD windows used with the old VAX-based controllers can be recalled with the "vax" button. More recent user-defined windows can be recalled in text format, or sds format, with the "txt" and "sds" buttons respectively (the ".txt" or ".sds" extension will be added automatically). Any newly-defined windows can be saved as a text file with the "Save Definition to File" button. Note however that this action will save not just the CCD window information, but also much of the "observation definition" information (object name, readout speed, etc.). These will overwrite the existing fields whenever the window definition is re-loaded, unless the "window only" box is ticked.

Validate: Pressing this button will cause all the observation parameters, including CCD window definitions, to be checked for consistency and completeness (e.g., no binning specified), and a warning given if anything is amiss. Starting an exposure will also cause a validation check to be done.

Last FITS Data File Written: The full pathname of the last Normal or Dummy exposure is recorded here, allowing the observer to cut and paste the file name into another application.

CCD Status and Control

This section shows the status of various detector functions. It is comprised of 4 sub-sections.

CCD Status

CCD_2 STATUS: This indicates which detector is connected to the controller, the array temperature and the heater voltage needed to maintain the array at the working temperature. If either the temperature, or heater voltage are out of range (usually as a result of running out of liquid nitrogen), the Status field will change from green to red, and a warning will be given. The current Run type (OBJECT, FLAT, ARC, etc.), Exposure/Readout progress, and Shutter status are also displayed in this section.

Once an exposure is commenced, the time elapsed as a fraction of the total time requested will continuously update in the large grey box at left. The status will change to "Exposing", and a red status bar beneath will also show the progress of the exposure. When the exposure completes, the shutter will close, and 2 beeps will be heard. The status will change to "Reading Out", while a cyan status bar will show the progress of readout. The large grey field at right will show the elapsed time, as a fraction of the expected total readout time.

CCD RUN SINGLE EXPOSURE: These are the buttons which actually inititate an exposure (or if repeats have been requested, a sequence of repeat exposures). The only difference is that they each define a different observation type, as recorded in the Observing Log and Archive, and in the OBSTYPE keyword in the FITS header. All these buttons are greyed-out while an exposure is in progress.

CCD RUN CONTROL: Once an exposure, or series of repeat exposures is underway, the only to modify the exposure parameters or terminate exposures is with these buttons, as most of the functions in other sections will be greyed-out.

Each of these will bring up a small dialog box into which you type the new value. To pause an exposure in progress (e.g. cloud drifting through the field, so you want to close the shutter briefly) click "Hold". To resume the exposure, click "Continue". To abort an exposure in progress (i.e. not even read it out), click "Abort". You will be asked to confirm if you really do wish to abort, and if you indicate "Yes", the system will reset then issue a confirmation when ready to continue.

CCD RUN SEQUENCE: Just like for IRIS2, observing sequences involving combinations of telescope offsets, UCLES reconfigurations, Semel polarimeter sequences, etc. can be implemented via Standard or User sequences using TCL. See the existing sequences for examples, or the Sequencer documentation, for examples of how to go about this.


This section displays the system responses to various commands, and the progress of exposures and observing sequences. Also shown here are the names of the data and dummy files as they are written to disk, and the amount of disk space remaining. If you see a warning that there is space for fewer than 100 images, please alert your Support Astronomer or the Night Assistant, who will then free up more disk space.


The UCLES Interface

Clicking on the "Ucles" tab will replace the Detector Setup display with one for controlling and viewing the status of UCLES itself. This tab contains two more tabs - the main one labelled "UCLES Control", and a second one labelled "UCLES Wavelength Setup".

UCLES Control

This section shows the status of various elements within the spectrograph, and allows them to be configured, either via "radio buttons" (where there are only 2 options), pull-down menus (for several fixed options), or numerical entry fields. Selecting a new value or position for an element will not actually cause it to be reconfigured, but the background colour for that element will change from green to red to indicate that the current position does not actually match that selected. Pressing the blue APPLY button at lower-left will cause that element to be moved, and the background colour will change to flashing cyan. Once the requested position has been achieved, the background colour will change to steady green again. The elements which might normally be set to CLEAR or OUT for observing (e.g. Post-Slit Filters, Hartmann Mask, etc.) will have their pull-down menu tab marked in red if set to any other position. This does not necessarily mean that they are out of position, but does allow the observer to tell at a glance if the spectrograph is ready to observe or not.

Several elements can be configured in parallel by selecting new values for each, then pressing APPLY once at the end. A third option is to right-click on any element name, which will bring up a popup dialog box. Entering a new value in this box and clicking "OK" will cause that change to be executed. More information on each of these elements is given below, or refer to the UCLES manual.

UCLES display

Beam Rotator: This can be set to one of:

Mirror Slide: This can be set to either:
Mirror slide positioning is also handled by the Calibration Lamp control.

Calibration Lamp: This can be set to one of:
The Lamp On Status field cannot be set by the observer, but simply confirms which lamp is currently switched on (NONE / QUARTZ / THAR / LASER / MOVING).

Lamp Filter 1/2: These can be set to any of 8 positions, usually CLEAR but Neutral Density (ND) and glass colour filters are available if required.

Slit Width: This allows the observer to specify a slit width, in any one of arcseconds on the sky; millimetres at the focal plane; or pixels (after binning, as specified in the Detector Setup section) on the detector. Simply click in the field you wish to specify, delete the current value, and enter the new value (or select from the pull-down menu any recent previous value wish to recall). Then click on the "set arcsec", "set mm", or "set pixels" button to the right of the value just entered. The equivalent values in mm and pixels (if you entered arcsec) are computed and updated. The slit width will not actually be adjusted until either the "Apply" button is pressed, or the observer right-clicks on the red Slit Width field and selects "OK" in the pop-up window. Note that either MIN or MAX may be entered in any of the 3 fields to specify the minimum or maximum slit width physically achievable.

Slit Length: As with the Slit Width field, the observer has the choice of specifying a slit length in either arcseconds, millimetres, or pixels (after binning, as specified in the Detector Setup section). Enter a new value in any of the 3 fields, or recall a previous value from the pull-down menu, then press the adjacent "set" button. The slit length will not actually be adjusted until either the "Apply" button is pressed, or the observer right-clicks on the red Slit Length field and selects "OK" in the pop-up window. Note that either MIN or MAX may be entered in any of the 3 fields to specify the minimum or maximum slit length physically achievable. MIN is useful to produce an "artifical star" spectrum for order-tracing when the primary targets have a weak or broken continuum, while MAX can be used if a blocking filter is available to suppress adjacent orders. A third option is SLAUTO, which will calculate the maximum slit length possible for the central wavelength currently configured, avoiding overlap of the reddest orders (this option can also be selected at the time of wavelength configuration).

Slit Shutter: This shows the current state of the shutter at the coudé slithead; usually SHUT, but it should indicate OPEN while an exposure is in progress.

Camera Shutter: This is supposed to show the current state of the shutter immediately in front of the CCD. This shutter is usually OPEN, unless it has been tripped by someone opening either the main door to the spectrograph room, or to the coudé slithead. Due to interlock modifications, this element is not currently updated in software. A better indicator is the brown UCLES shutter control box - when the Camera Shutter is indeed OPEN, the "CES" LED should be flashing red, but if SHUT it will be a steady green. The shutter can be opened manually from the rack in the coudé east anteroom.

Focal Modifier 1: The focal modifier wheel holds a number of components, including focal modifiers for UCLES which can act to increase throughput in conditions of poor seeing - select BLUE or RED depending on the wavelength you are working at, or just IN to let the system choose for you. Select OUT (= CLEAR on startup) to withdraw the focal modifier. The UHRF focal modifier is only for use with UHRF, while IODINE will position the Iodine cell in the beam for use in planet search or asteroseismology programs.

Post-Slit Filter 1/2: These can be set to any of 8 positions, usually CLEAR but Neutral Density (ND) and glass colour filters are available if required. Narrow-band filters which pass less than one order can be placed in Post-Slit Filter Wheel 2, allowing the use of the maximum UCLES slit length (56 arcsec) on extended objects. Consult the AAO Software Group for assistance in updating the list of available filters, and ensuring the right filter information goes in the FITS header. The Planet Search exposure meter (EXPM) is also mounted in Post-Slit Filter Wheel 2.

Echelle: The actual échelle grating currently in position is indicated in the Summary section velow this, but when the echelle grating is in motion during a reconfiguration, this field will flash cyan. It is possible to switch gratings manually by right-clicking on this field, but grating changes would normally be carried out from the UCLES Wavelength Setup tab.

Echelle Theta / Echelle Gamma / Slit Angle: These fields show the current échelle theta and gamma angles required to place the wavelength of interest near the centre of the CCD, and a horizontal slit image in the central order. Usually these would be the values calculated as part of the UCLES Wavelength Setup procedure. It is possible to adjust these manually, by right clicking on one and entering a new value. Otherwise, these fields are greyed out, to reduce the risk of inadvertently changing the grating position or slit angle.

Echelle Theta Offset / Gamma Offset / Slit Angle Offset: These 3 fields contain numerical offsets to be applied to the calculated theta, gamma, and slit angles before being sent to the UCLES control micro. They will usually be determined by your support astronomer for your CCD and wavelength of main interest; once determined however, they are equally applicable to any other wavelength or grating. They may be tweaked by the observer (e.g. to place a hot/bad column of the CCD between orders), but again only by right-clicking on the respective fields and entering a new value. Be aware however that as soon as the OK button is pressed in the pop-up, these new offsets will be applied to the current theta / gamma / slit angle, and the grating/slit will be shifted accordingly, without waiting for the APPLY button to be pressed. Be very certain therefore that you have taken all necessary arcs or flats you require for the current setup, as once any small adjustment is made to the grating or slit angles, it will be virtually impossible to go back to the exact same setup to sub-pixel precision.

Hartmann Mask: The Hartmann Mask is a flap which can block half the collimator field of view, and be rotated through 180 degrees, and is used for knife-edge focus checks by the support astronomer and technical staff. It should be OUT for observing - if it is in the beam and set to either UP or DOWN position, it will be marked in red to alert the observer.

Prism: The cross-dipsersing prisms would normally be IN for observing, at an angle determined by the UCLES Wavelength Setup procedure. If set to OUT, this would be highlighted in red.

Collimator: UCLES has 2 collimators, one aluminium-coated for work shortward of 4000 Å, and the other silver coated for longer wavelengths. The appropiate collimator is selected automatically by the UCLES Wavelength Setup procedure, but can be overridden here if necessary.

Collimator Focus: UCLES internal focus is set by driving the collimator in or out, but due to the slow focal ratio the focus changes very little over the full range. The optimum focus value is determined by the support astronomer and technical staff at the start of the block with any particular CCD, and does not usually need to be checked or changed during a run.

Summary: This section is for information only, and indicates the last-requested échelle grating, central wavelength and order. Depending on how much theta and gamma or their offsets have been adjusted since then, this may or may not correspond exactly to the wavelength in the centre of the CCD. Calculations of the bluest and reddest wavelength covered by the readout window have not yet been implemented. If an UCLES configuration has recently been saved to disk, or loaded from disk, their filenames will also be shown here.

APPLY: Pressing this button will send a series of requests to the UCLES control micro to move any of the elements whose requested position is different from their current position (within an ADU or so), as indicated by having their fields highlighted in red.

SAVE CONFIG / LOAD CONFIG: A "snapshot" of the current spectrograph configuration can be saved as a simple text file to disk by pressing the "Save Config" button. It can later be recalled using the "Load Config" button, and the spectrograph configured accordingly using the "Apply" button. Note that due to limitations of the drive mechanisms and encoders, elements such as the slit width and grating position may not match precisely that requested.

CURRENT: If after setting a number of elements to new values you elect not to change the setup, you can press "Current" in order to have the system poll the micro for the current configuration and restore these values in the GUI.

UCLES Wavelength Setup

From the main UCLES tab, clicking on the UCLES Wavelength Setup tab will replace the main UCLES configuration screen with the following display. This is the primary means of configuring the spectrograph to a new wavelength, replacing the old CENTRE and CONFIG commands on the VAX.

Wavelength Setup

Central Wave Length angstrom: Enter here the wavelength you would like to centre on, or the order of which you would like to centre on.

Echelle: Select which échelle grating you prefer - recall the 79 l/mm grating allows a longer slit than the 31.6 l/mm grating, at the expense of some wavelength coverage and (in the reddest orders) you may not get the entire free spectral range on the CCD. The resolution is the same for both gratings.

Use peak: Tick this box if you would prefer to have the CCD centred on the peak of the blaze for the order containing your wavelength of interest, rather than on the wavelength itself.

SLAUTO: Tick this box if you would like the software to compute the maximum slit length possible for the central wavelength to be configured, avoiding overlap of the reddest orders, and set the slit to this length as part of the reconfiguration. You can also request this after the reconfiguration using the Slit Length field in the UCLES control tab.

C Binned Pixel Size microns / D Binned Pixel Size microns: These are for information only, confirming that the system recognises the current equivalent pixel sizes in the spatial (C) and spectral (D) axes, as these are required for the SLAUTO calculation.

CONFIGURE: Pressing this button will send the necessary commands to the UCLES control micro to move the grating, change the slit length (if SLAUTO selected), collimator, prism position, etc. The display will switch back to the UCLES Control tab, and the elements currently in motion will flash cyan until they have arrived at their requested locations. In the event that any element does not arrive within a reasonable time, the system will send another request automatically, which will usually be enough to ensure all movements are completed.

Cancel: Press this button if you elect not to change the spectrograph setup (or just select the UCLES Control tab).

Skycat Image Display

The image display for the ODC is built upon the ESO Skycat RTD tool, with some extra capabilities added to enable interaction between the ODC  system and the telescope. The display is updated in "real time", that is after each readout "slice" of the array. The slice size is 1024 rows by default, but this can be changed with the Commands -> Set slice size option of the Optical Detector User Interface.

When viewing old images while taking new data, you may wish to temporarily suspend the real-time display. You can do this by selecting AAO-Detectors -> Disconnect, then AAO-Detectors -> CCD_2 (or CCD_1) when you are ready to resume the real-time display.

Some information on the main features of Skycat can be found on the ESO Skycat Web pages.

You can call up coordinates for objects from databases like NED or SIMBAD using the Data Servers -> Catalogs menu, and selecting the appropriate catalog. You will get a pop-up window in which you can enter an object name or co-ordinates, after which the catalog will be searched and a list of possible options returned. You can then highlight your object in this list of sources, and send the coordinates of that object to the CCS and slew the telescope by selecting Telescope -> Slew to Selected Object. (If Skycat has just been started, you will need to precede this with a Telescope -> Reset Server Connection... )

You can also call up targets from a catalog of your own, as in this example, in which object ID, RA, and Dec are separated by a <TAB>, you should save it with a ".tab" extension, then call it up from Data-Servers -> Local Catalogs -> Load from file... Note that even a single extraneous character in any line of this file can result in the catalog file not being loaded at all, or cause Skycat to hang after requesting a Slew.


Using GAIA as the Real Time Display

The Starlink GAIA image display shown above (click on the image to see it at full resolution) is also based around Skycat, and allows the use of "plug-ins" for expanded functionality. Chris Tinney at the AAO has developed one such plugin which enables quick estimation of the seeing and S/N in any order of an UCLES spectrum, which others may find of use. To use this, exit from Skycat, then start up gaia from the same terminal that the ODC was started from:

> gaia &

This will now connect automatically to the data acquisition system. There is a new File -> Open latest... option (or Ctrl + Shift + o) which, if you have already displayed an image from a directory, will find the newest image in that directory and display it. The spectral profile tool can be selected either from View -> Pick Spectrum... ; Image-Analysis -> Mean X & Y profiles... ; or just Ctrl + p.

spectral profile

Once selected, gaia will wait for you to click and drag out a box encompassing part of a single order. After a brief period, the panel at left will appear, showing collapsed profiles in X and Y (note that unlike the View -> Slice... option in Skycat, you will not be prompted before marking the box on the display). By indicating which direction is spectral/spatial, and selecting the pixel scale, gaian and read noise appropriate to your binning and readout speed, the FWHM of a cut through the mean spectral profile is determined both in pixels and in arcseconds. The mean profile is shown in black, the fitted background in blue, and the fitted Gaussian in red. You also get the median count level in the spectral direction (shown in green in the second plot), which is used to estimate integrated counts per pixel above background, i.e., how many counts you are collecting from your object, to monitor S/N, seeing, cloud, etc.

You can drag the box around the image, stretch it, etc. and the profiles will update. The marked box stays put when you load a new image, so all you have to do is hit the "Update" button at the bottom to get the same information from the same part of your spectrum for every exposure. You can use the left mouse button in either plot window to select an area to zoom in on, or the right mouse button to zoom out again.


The Portable Telescope Control System (PTCS) GUI duplicates much of the functionality of the telescope control console and night assistant's terminal. From the "Commands" menu, select "New Target¨ and enter the RA, Dec, Epoch, proper motion, etc., then hit "Slew" to send the coordinates to the Control Computer System (CCS); this may take a few seconds - watch the CCS terminal, which should load the new coordinates and commence the slew. Although the PTCS cannot access or store a file of coordinates like the CCS can, it is possible to call up catalogued objects by name, or from an input catalogue provided by the observer, using the "Slew to Catalog Object" function within the Skycat display.

To command a specific offset, the observer must first click on the green "Control OFF" button, which will then change to "Control ON" highlighted in yellow. Select Commands -> Offsets... and enter the offsets in arcseconds. Note that for RA, the offsets are in arcseconds on the sky, not arcseconds of polar axis rotation as they are on the night assistant's console. To go back to the Base position, select "Centre". Note also that switching Control ON (which can also be commanded from an Observing Sequence) makes the current telescope position the new Base position.


Stuart Ryder, sdr -@- aao.gov.au