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SPIRAL control software

Calibration system
Using the calibration system
Basic operations
Bad Columns
There's no light in my flat fields!
Orientation on the sky
Determining the instrument aperture (APoff)
Offset Guiding

The SPIRAL control GUI is a cut down version of the AAOmega control task, tdfct. To run the software, log into aatlxy as aatinst and type spiral.  The control task will be Familiar to any 2dF/AAOmega user.  There are sub sections for Telescope control, The CCD system and the AAOmega spectrograph.

Usefull information on target acquasition with SPIRAL can be found on the acquasition and overheads page.
A page of observing notes can be found on the Observing notes page.

Calibration system

The SPIRAL calibration system is not fully integrated with the control task.  The system is in two parts, consisting of
Both systems have a calibration screen which is driven into position automatically when any calibration lamp is activated, and which is cleared when the last lamp in each system is turned off.

To run the calibration system, log into aatlxa (NOT aatlxy or aatlxb) and type lamp.  This will bring up a control GUI with a series of lamp buttons.  Toggling the buttons on or off turns a selection of lamps on or off, and drives the relevant calibration flap into/out of  position if it is not already.

The chimney system is primarily used only for the quartz-halogen flat field lamp.  The IFU fore optics system is used for arc lamp illumination.  The arc lamps in the chimney are to faint to be very useful with SPIRAL, with the exception of the He and Ne lamps.  The He and Ne lamps cannot be successfully used at the same time as the IFU for optics CuAr, FeAr and ThAr lamps, as the fore optics screen currently block the light path to the chimney lamps.

Please leave the quartz lamp on for the bare minimum length of time, to avoid excessive heat load on the colour balance filter.  Arc lamps can be left on for longer periods if required (e.g. for focus etc.).

Using the calibration system

The lack of full integration of the calibration system with the control task requires some additional user input.  When arc or flat exposure are taken a pop-up dialog will appear asking the user to indicate which lamp combination is in use.  The user should select the appropriate lamps and then take the exposure.

Basic operations

This section is in preparation and so is just basic notes at present.

For a Position Angle (PA) of 0 degrees, the IFU is oriented with the long axis East-West.
To place the long axis at a PA of 45 degrees (NE to SW), one must rotate the IFU head unit anti-clockwise, so as to align the markings on the rotator with the -45deg mark (Confirmed by observation on - 061227, with some difficulty.  Check again).

Setting the PA for the SPIRAL control software.

If the PA has been manually adjusted, then set the new value in the control software using:

Commands->Set IFU Instrument Mount Parameters

From the SPIRAL control task Commands menu.  This adds the relevant information to the image headers, and therefore allows the electronic log to pick them up.

Bad Columns

There are a number of bad columns on the Blue CCD.  The first set is at x~1024 the second at x~1610.  For stellar populations work, one must take care NOT to align these bad regions with a key diagnostic index.  For example, if MgB is the principle line of interest, then one should place this at x~500.

There's no light in my flat fields!

There are a number of reason for there bing no light in SPIRAL flat fields or arcs.  Before assuming something is horribly wrong, check the following:

Orientation on the sky

This is based on PA=0.  This place the Long axis of SPIRAL East-West.
To rotate to higher PA (measured East of North as usual), rotate the IFU anti-clockwise at the Aux-Focus port of Cass.  The rotator mechanism is correctly marked with positive and Negative angles (rgs - 0612).  Some advanced planning of the expected motion of start on the IFU image, and of the required telescope offsets to achieve ones acquisition, is of great value here, the geometry can be very confusing at 3am.

The data reduction software currently (0612) shows the wrong aspect ratio for SPIRAL.  In the 2drfdr reconstructed SPIRAL image, the x-axis is the SHORT axis (16 pixels, NS for PA=0) while the (shorter on the screen) y-axis is the SPIRAL long axis (32 pixels, EW for PA=0).

For PA=0, the 2dfdr SPIRAL reconstruction is oriented such that :

NOTE: 2dfdr screen has the WRONG aspect ratio, the y-axis below IS the 32pixel LONG axis for PA=0
             E this edge 16 pixel short axis
        ---------------------------
        |                         |
  S     |                         |      N This edge 32 pixel long axis
        |                         |
        ---------------------------
                                       W
NOTE: the tv guide cameras where swapped over in March 2007, to give a wider FoV to the guide probes.  The senses of offsets given below need to be confirmed again.

Telescope moved Effect on 2dfdr SPIRAL image
North Moves star to the left
South Moves star to the right
East Moves star down
West Moves star up


At PA=0, the SPIRAL short axis is the North-South axis.  When viewed on the SkyCat CCD windows, movement in this North-South axis will be seen as movement between the 16 banks of 32 fibres.  Movement in the East-West axis will be seen as movement within a given back of 32 fibres.  To move the star DOWN the CCD, into the next fibre bank on the SkyCat display, offset-guide the telescope  in increments of 0.7arcsec South.

Determining the instrument aperture (APoff)

At the beginning of any new SPIRAL run, the instrument aperture will need to be reconfirmed and possibly adjusted.  This is achieved as follows (incomplete)

  1. Take a flat field and arc frame, ultrafast readout is fine.  Do this during the afternoon after focusing.  Take the frames as real data (so that 2dfdr will reduce them correctly).
  2. Reduce the flat and arc with 2dfdr.  There is no need for a science grade reduction, so use TRAM extraction and turn off the CRreject and scattered light filtering.   You should probably create a calibration .idx file for this.  Turn off the sky subtraction and image combination as well, since for individual observations of bright stars we don't need them and they may well fail.
  3. In Twilight, find a SNAFU star near Zenith.  Ask the night assistant to set the APoff values back to the last known SPIRAL values, and to drive the focus to the last known.  Acquire the star using the Cass acquisition camera.  To avoid telescope drift, once you are happy with the acquisition TV image, rapidly switch to SPIRAL, find a guide star, and star guiding.
  4. Now take a short exposure (10-30sec?) of the SNAFU star.   Again, take the data as a normal run, but ultra fast readout is fine.  Reduce the data in normlay way with 2dfdr.  Now use the Reconstruct SPIRAL IFU option from the PLOTS menu.  This will produce a 2D map of the star (provided the current APoff is not to far off).  Set the scaling to Min-Max (rather than 95%), centre the cursor over the star and hit X or Y to get a 1D slice through the star.  Estimate the FWHM.
  5. Now cycle the telescope focus through a range around the current focus value until the best focus is found (typically +/- 3 observations at 0.2mm top end movement will be fine).
  6. Now that the telescope is focused onto SPIRAL, the APoff can be updated if required.  The instrument aperture is updated by the night assistant using the TCS, but the astronomer will need to take a series of exposure on the SNAFU star and provide the NA with the offsets require to bring the Star to the center of the IFU.  Use the Reconstruct SPIRAL IFU option should be used on each frame and the XY position the the star found in the IFU.  Use the offset information detailed above to derive the correct APoff values.  Note the 2dfdr aspect ratio problem (2dfdr SHORT y-axis is the IFU 32 lens LONG axis, which corresponds to East-West for PA=0).

Offset Guiding

The most reliable way to acquire a file is to "peak up" on a bright star with known coordinate and close to the target.  One acquire in th e usual manner, starts the guider, and then take short (ultrafast readout) frame and uses the reconstructed SPIRAL image to center up on the star, applying small guider offsets.   Once happy with the acquisition, one then applies a larger guider offset to place the target on the IFU.

When using placing guider offsets :
  1. Note that the GUI Places RA above Dec
  2. The user must specify the direction (E/W, N/S for each component)
  3. The sense of the offsets is that you give the GUI the require telescope offsets, the software will then offset the guider in the opostie sense to achieve the require telescope offset on target (i.e. do not flip the offset your self).
  4. The guider offsets are arcseconds on-the-sky and so are not cos(dec) corrected (i.e. a single IFU lens offset E/W will be 0.7arcsec regardless of the Declination).


Rob Sharp (rgs@aao.gov.au)