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The Southern African Large Telescope (SALT) currently has three instruments: the imaging SALTICAM, the new High
Resolution Spectrograph (HRS) which is in the process of being commissioned and the Robert Stobie Spectrograph
(RSS). RSS has multiple science modes, of which long slit spectroscopy was originally commissioned; We have
commissioned two new science modes: Multi Object Spectroscopy (MOS) and Fabry-Perot (FP). Due to the short track
times available on SALT it is vital that acquisition is as efficient as possible. This paper will discuss how we
implemented these modes in software and some of the challenges we had to overcome.
MOS requires a slit-mask to be aligned with a number of stars. This is done in two phases: in MOS calibration the
positions of the slits are detected using a through-slit image and RA/DEC database information, and in MOS acquisition
the detector sends commands to the telescope control system (TCS) in an iterative and interactive fashion for fine
mask/detector alignment to get the desired targets on the slits. There were several challenges involved with this system,
and the user interface evolved to make the process as efficient as possible. We also had to overcome problems with the
manufacturing process of the slit-masks.
FP requires the precise alignment each of the two etalons installed on RSS. The software makes use of calibration tables
to get the etalons into roughly aligned starting positions. An exposure is then done using a calibration arc lamp,
producing a ring pattern. Measurement of the rings allows the determination of the adjustments needed to properly align
the etalons. The software has been developed to optimize this process, along with software tools that allow us to fine
tune the calibration tables. The software architecture allows the complexity of automating the FP calibration and
procedures to be easily managed.
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