Changes
1.0m
,/* Determining pointing offsets using a bright star */
# Click "TARGET" and type the RA & Dec of the bright star into the appropriate boxes, then click "SET" and "CLEAR". The coordinates will appear in yellow on the monitors above the TCS and on the observing floor to help you point to the target.
# Type the '''equinox''' of the bright star coordinates into the "SET EQUINOX" box and press "ENTER" on the keyboard.
'''At the blue console by the North pier:'''
# Switch the central toggle switches to FAST.
# Use the yellow RA \& Dec buttons to slew to the bright star, watching both ends of the telescope as well as the coordinate display monitor. You should point to within 30s (RA) and 1-2 arcmin (dec) of your target coordinates.
# Switch the central toggle switches to SLOW to commence tracking.
'''Back at the TCS:'''
# Set "Exp Time" to ~1s and "WINDOW" to "Full frame" to take images with the acquisition camera.
# Use the hand paddle for fine adjustment of the telescope to the star's coordinates, while watching the image display for the bright star to appear.
# If the bright star is not apparent, adjust "Exp Time" to ~10s and look for light from the star beaming in from one side of the image, revealing its position. Looking through the finderscope might help determine in which direction to move the telescope. If this fails, reduce the exposure time and scan the field systematically in RA & Dec.
# Once the bright star appears, select the minimum exposure time, centre the star on the image and click "P" by the target button.
# Select "ZERO POINTS" → "Enter RA & Dec of Star", then type the '''catalogue coordinates''' of the bright star into the boxes and press "SET".
# The RA & Dec zeropoints will be displayed in the message box. Note them down with the HA \& Dec as you will need to re-enter them using "ZERO POINTS" → "Enter Zeros Directly" if the TCS software is restarted, or if you return to this part of the sky after using different zeropoints in a different position. You do not need different zeropoints for different equinoxes. There is no need to note the collimation coefficient as it is ignored by the pointing model.
== Acquiring a target ==
# Follow the facility start-up procedure in Section~\ref{sec-facstartup}.
# Check that the selected target is within the observing limits given in Section~\ref{sec-limits}.
'''On the TCS:'''
# '''Initialise''' the XY-slides.
# Move the '''guide mirror into the beam'''.
# Click "TARGET" and type the RA & Dec of the target into the appropriate boxes, then click "SET" and "CLEAR". The coordinates will appear in yellow in the monitors above the TCS and on the observing floor to help you point to the target. (If you cannot see a "TARGET" button, click the "O" in the left-hand corner below the "SET EQUINOX" box.)
# Type the '''equinox''' of the target coordinates into the "SET EQUINOX" box and press "ENTER" on the keyboard.
'''At the blue console by the North pier:'''
# Switch the central toggle switches to FAST.
# Use the yellow RA & Dec buttons to slew to the target, watching both ends of the telesope as well as the coordinate display monitor. You should point to within 30s (RA) and 1-2 arcmin (dec) of your target coordinates.
# Switch the central toggle switches to SLOW to commence tracking.
'''Back at the TCS:'''
# Set "Exp Time" to ~2-4s and "WINDOW" to "Full frame" to take images with the acquisition camera.
# Use the hand paddle for fine adjustment of the telescope to the target's coordinates while watching the image display for the target field to appear. Comparison with an $8 \times 8$~arcmin finderchart is most helpful.
# The position should be accurate if you have followed the procedure in Section~\ref{sec-brightstar}, so check your zeropoints. If not, adjust "Exp Time" to search for patterns in fainter stars to compare with your finderchart. If this fails, then reduce the exposure time and scan the field by systematically adjusting RA & Dec.
# Once the target is identified, position it on the image display such that it falls on the centre of the science CCD.
* '''For STE4''', position the star approximately on coordinates (210, 270) of the TCS image display, to coincide with the centre of the science detector (for '''STE3''', approximately (180,190)).
* Move the '''guide mirror out''' to direct the beam to the science detector.
'''On the instrument PC:'''
* Take a snapshot (STE3/4) or preview (SHOC) to check the positioning of the target on the detector and adjust using the handset.
* Using '''STE3/4''', video mode can be invoked by clicking "Snapshot", entering an integration time, selecting "Video" and clicking "Ready". It can be stopped by clicking "Snapshot" and "Stop". Video mode automatically prebins the CCD, so remember to change back to 1x1 afterwards, if appropriate.
* '''For a short run of short exposures''', you may set up a module (STE3/4 - see "SAAO~CCD Camera Control Program version 1.2", J.W. Menzies) and begin to observe
'''or'''
* '''For a long run or for exposures ≥100s, you should locate a guide star and setup the autoguider before integrating on your target.
== Finding a guide star & autoguiding ==
'''On the ltsp PC:'''
* Open a terminal (click the black screen icon on the top menu panel)
* Type '''cd /usr/local/saao/40inGuiders'''
* Type '''source runit'''
'''In the DS9 interface that pops up:'''
* From the "Analysis" pull-down menu, select "DSS Server".
* In the "DSS Server" window, click on the "DSS Server" menu and select either "DSS@STSCI" or "DSS@ESO". SAO no longer connects.
* Enter RA & Dec of target (using colons to separate coordinate units) in 20'x20' field of view and click "RETRIEVE".
* Once the field image loads with the target in the centre, choose a relatively bright star outside the circle. Place the mouse cursor over the star and read off the {\bf XY slide} coordinates in the grey info area above the image.
'''On the TCS:'''
* With the '''guide mirror in beam''', click on "Move XY", then on the target star position in the acquisition image, then on "Zero XY". This centres the field on the target so that the XY slide coordinates will be compatible with those you read off DS9 for the guide star.
* Move the '''guide mirror out of beam'''.
* In "Exposures & Guiding" set "ExpTime" ~2s (adjust as necessary).
* In "XY Slides Control", click "Go To" and enter X and Y slide coordinates of chosen guide star from DS9.
* In "Pointers" click "XY+Win+G" then click the chosen guide star. This will centre the guide star on the image, window the chip and begin guiding.
* To stop or restart guiding (e.g. after brief intervals of cloud), press "GUIDE".
== Current known issues (last updated Nov 2013)==
