AutoGSS Guide v1

AUTOGSS User Guide

Document No: ING-AUTOGSS-005

Imaging:
ACAM or LIRIS

Spectroscopy:
ACAM ISIS LIRIS

Startup

To start up AutoGSS, open a new terminal, log in to taurus and start it up from the observing observing system:

obssys
autogss &

Setup

Before being able to use the Auto functions to start guiding automatically, it is necessary to start the autoguider framing and put it in guiding mode with GUIDE (not just TV). You can leave it in this mode all night and just open and close the loop to stop and start guiding when required.

In the Setup Tab, set the Preferred Magnitude and the Autoguider Filter required. For clear conditions and the AG-CLEAR filter, you can usually use the default Preferred Magnitude of 13. It’s recommended to select a brighter Preferred Magnitude for the I-filter and for cloudy conditions. You can also change the Bright and Faint Magnitude limits too if desired.

AutoGSS GUI

Search Tab

Search Parameters Section

Clear removes the text from the white box with RA and Dec
Target and the white box on its right allows you to enter RA and Dec in the white box, or it shows them automatically if Auto Target is checked
Rotator Sky PA allows you to enter the sky PA manually, or it shows the Sky PA automatically if Auto Target is checked
Aperture Offset X,Y allows you to enter Aperture Offsets (x,y) manually, or it shows them automatically if Auto Target is checked
Instrument allows you to select the instrument in use, or shows it automatically if Auto Target is checked. Instruments supported are: ISIS, LIRIS, PFIP (only to predict guide star positions, not to move the probes), ACAM, Integral (only to predict guide star positions, not to move the probes), Ultracam, CassOwn, INTCass. For any other instrument (e.g. AF2) it will show Unsupported
Equinox gives you a choice between J200 and B1950, or it shows the current Equinox automatically if Auto Target is checked
Search button performs a search for guide stars and prints them in the lower box
Staralt PA plot plots the object visibility with the Sky PA

Automatic Functions:

Auto Target will automatically retrieve the Instrument, RA, Dec, Sky PA, Equinox and Aperture Offsets (x,y) on startup or on the change of any of these.

Auto Search is the same as pressing the Search button i.e. it searches automatically for guide stars with the given Instrument, RA, Dec, Sky PA, Equinox and Aperture Offsets (x,y) and lists the possible guide stars in the large box below.

Auto Probe automatically moves the autoguider probes into the correct position for the guide star, which will be automatically selected according to the Preferred Magnitude and other parameters set in the Setup Tab. If the target, Sky PA or aperture offsets are changed, the probes will move, except that the probes will never move when the t/s is GUIDING.

Auto Guide On starts guiding automatically if it is checked as soon as:
a) the telescope is tracking and
b) the autoguider probes are in the correct position
N.B. The autoguider needs to be running (i.e in GUIDE mode) for guiding to start automatically.

Autoguider Section

Track Guide Star If this box is checked, the autoguider green box will follow the guide star. If changes are made on the autoguider, they will be shown here
Guide Box Size allows you to select the size of the green autoguiding box. If changes are made on the autoguider, they will be shown here
Integration allows you to select the autoguider integration time. If changes are made on the autoguider, they will be shown here
S/N shows the S/N calculated by the autoguider, updated every 3 seconds
Seeing shows the seeing calculated by the autoguider, also updated every 3 seconds
TCS Status shows whether the telescope and rotator are:

STOPPED
MOVING (in blue letters)
TRACKING (in black on dark blue)
GUIDING (in green)
ENG MODE

Control Buttons:

TV to start the autoguider in TV mode
GUIDE to start guiding
STOP to stop either TV or GUIDE modes
FIELD to take one exposure and mark the possible guiding objects
OPEN to open the guiding loop - this keeps the autoguider running and sending corrections to the TCS, but the TCS does not guide
CLOSE to close the guiding loop - the TCS starts to guide

Probe Section

Go To Star moves the autoguider probes into position for any chosen star from the list, which is selected by clicking once on the line of the star you want
Go To Coords moves the autoguider probes to AGR and AGT as entered in the two boxes on the right
+/- buttons increase or decrease AGR or AGT by 1000

The Results window below gives all the possible guide stars, selected according to the input search parameters on the Setup tab

Predicted Probe Coordinates gives in copyable text format the probe position of the selected guide star

Current Probe shows the current probe positions (the same as you’d see in the mimics or on the instrument control GUI).

Setup Tab

Instrument/Focus Configuration

Shows the Instrument (taken from the TCS), Max number of results, Magnitude limits and Preferred Magnitude for the guide star.

Filter and Focus

Here you can select the autoguider filter from the drop-down menu and also change the autoguider focus, either by entering a value in the white box and hitting Move Focus, or by increasing or decreasing it by 200 units using the - and + buttons.

Autoguider Tab

Shows the name of the current autoguider connected and its status: Connected or Disconnected.

Results Tab

Shows all the input parameters for the guide star search

Configuration Tab

Shows the configuration settings, i.e. how the guide star predictions are calculated. Do not change anything here, unless you know what you’re doing! If you do change something, you can restore the defaults by restarting AUTOGSS.

Observing Techniques

General Notes

With all 4 Auto boxes ticked, on source change AUTOGSS will:

1) pick up the RA, Dec, Sky PA, aperture offsets and Equinox
2) search for a list of possible guide stars according to the parameters in the Setup tab
3) move the probe to the required position for the guide star with magnitude closest to the Preferred Magnitude
4) as soon as the t/s is tracking and the probes are in position, guiding will start automatically (the autoguider has to already be in GUIDE mode)

For spectroscopy, non-standard procedures will be needed for scenarios such as placing 2 targets on the slit. If you have slewed to the coordinates of one of them and this then has to be moved a long way along the slit, say more than about 25”, the guide star will need to be re-centred by moving the probes. The best way to do this is to stop guiding (OPEN the loop) and move the targets in Handset (A)POFF mode so that the probes will move automatically to keep the guide star well centred. Then CLOSE the loop.

ACAM or LIRIS Imaging

Check all 4 Auto boxes
Select the required integration time
Select autoguider box size, taking into account the dither pattern to be used including jitter for LIRIS, which increases the size of the dither pattern further
GOCAT to the target and set Sky PA
Check that the guide star is sufficiently well centred so that it will not be lost from the autoguider’s field of view during the dithering

If the observer requires any offsets before observing, then depending on the size of the offsets it may be necessary to switch off guiding temporarily (using the OPEN loop button) and move the t/s and probes so that the guide star is still sufficiently well centred. For small probe movements, you can use the r,theta +/- buttons to move AGR and AGT by +/- 1000 units. For larger movements, it is quicker to enter the required AGR and AGT into the two boxes and hit the Go To Coords button. Then CLOSE the loop to restart guiding. Alternatively, you can do (small) offsets using the Handset in (A)POFF mode. If the TCS status is guiding, then the probes will not be able to move, so if they do need to be recentred then you need to OPEN the loop. AUTOGSS has been tested with the ACAM dither script multdither.py and works fine with it.

ISIS Spectroscopy

Check all 4 Auto boxes
Select the required integration time
Select autoguider box size
GOCAT to the target and set Sky PA
After guiding starts automatically, the TO should do the acquisition in handset (A)POFF mode, with guiding on all the time.

No dithering is needed along the slit, so once the target is acquired the guide star doesn’t need space around it to move, so a small autoguider box size can be used, e.g. 100 pixels. Usually the target will be found very close to the slit and so it’s unlikely that the guide star will need to be re-centred.

LIRIS Spectroscopy

Check all 4 Auto buttons
Select the required integration time
Select autoguider box size, taking into account the nodding size including jitter, which increases the size of the dither pattern further
Enter the appropriate aperture offset into the TCS so that the target will begin close to the centre of the slit in x and near y=400 (assuming this is where the observer wants to place it). The aperture offset should have been calculated during the LIRIS first night checks. If it wasn't, just use any previous value, which should be good enough.
GOCAT to the target and set Sky PA
Check that the guide star is sufficiently well centred so that it will not be lost from the autoguider’s field of view during the nodding
The observer will finetune the acquisition and guiding should be on throughout

ACAM Spectroscopy

Check all 4 Auto buttons
Select the required integration time
Select autoguider box size
Enter the appropriate aperture offset into the TCS (ENTER AP 0 X Y) so that the target will begin close to the default acquisition position (assuming the observer wants it there). The aperture offset was measured in April 2015 and found to be -25, -10. This should remain quite stable over time.
GOCAT to the target and set Sky PA
Check that the guide star is sufficiently well centred so that it will not be lost from the autoguider’s field of view during the acquisition
Acquire the target using ACQTOOL - guiding can be on throughout

No dithering is needed along the slit, so once it’s acquired the guide star doesn’t need space around it for offsets.

Fiona Riddick 17/11/2014