* '''For a long run or for exposures ≥100s, you should locate a guide star and set up the autoguider before integrating on your target.
=== Finding a guide star & autoguiding ===
'''On the ltsp PCTCS:'''* Open a terminal # Ensure that the XY slides have been initialised (click "Initialise" under XY slides control).# Open the guide star software (the black screen icon of a star with a long tail).# Enter coordinates of the field and click "GET IMAGE". A window should appear displaying a DSS image.# Click on a bright star outside of the top menu panelgreen circle in the DSS image. NOTE: this chart is centred on the given coordinates. If you have adjusted the position of the target to be away from the centre of the acquisition frame, there will be the same offset in the selected guide star.# Under "XY Slides Control," click "GoTo GS". The star should appear in the acquisition image. If not, try a different star.# Under “Pointer" click "Guide Star" , then click on the chosen guide star in the acquisition camera FOV. This will put a blue box around the star and begin guiding. NOTE: if the star is near a hot pixel, that could cause trouble with guiding. Click "Move XY" and click on the star: this will center it (just moving the XY stages, and not effecting the science target).* Type '''cd /usr/local/saao/40inGuiders'''# To stop or restart guiding (e.g. after brief intervals of cloud), press GUIDE.* Type '''source runit'''# To change exposure times, press STOP, select exposure time from the drop down menu under Expose.
'''In the DS9 interface that pops up:'''
* 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".
== TCS operations at the end of an observation ==
