===Setting up the slit position on the TCS - using the SpUpNIC Control GUI===
The purpose of this step is to figure out where on the acquisition image you need to place your star, in order for it to land close to the ideal spot on the slit. Very bright stars can be seen reflected on the slit jaws, and can be placed on the slit directly, but this is not the case for fainter stars, which need the superior reflectivity of the guide fold mirror in order to be seen on the acquisition camera. This position should be approximately stable throughout your run, but you can fine-tune the target location using the rear-of-slit camera.
<!--# Move the guide mirror into the beam, either by setting the ''Acquisition'' state in the ''Lamp/Mirror Settings'' pane of the SpUpNIC control GUI (if it says Guide Mirror ''Science'', click ''Change''), or by clicking on the guide mirror in the instrument schematic. --># Move the fold mirror into the beam: on the right-hand side of the TCS GUI is a big, green button that should say "FOLD MIRROR IS IN BEAM". Click on it if it says the mirror is out of beam.# Press "Center" on XY-slides control.# Set Guide Camera Focus to ~29000. # Acquire a bright star (e.g. ~4th mag from the Bright Stars chapter of the Sutherland Almanac, available in the warm room), roughly centre it in the acquisition camera field and continue exposing. # Focus the telescope (start at ~2180) using the shortest possible exposure time (focusing is best done with a fainter star, but this will be sufficient for getting the position). # Move the guide fold mirror out of the beam (i.e. centre the mirror so that light can go down the central hole). # Move the rear-of-slit mirror into the beam (On SpUpNIC, ''Lamp/Mirror Settings'' pane, RoS mirror change from ''Out of beam'' to ''In beam'').
# Turn on the slit illumination (in the ''Instrument Setup'' pane, ''Change'' to turn on the lamp). Tune the exposure time/LUT sliders on the TCS until you can clearly see the slit running horizontally across the acquisition image, approximately halfway up.
# Using the hand paddle, move the telescope to place the star on the slit, approximately one quarter of the image width away from the right-hand edge.
# The resulting image will be displayed on the Quick-Look GUI, on Monitor 2. You are aiming for the spectrum to fall on approximately the central row of pixels within the image area (note that this is a roughly central band that only covers about half the vertical extent of the CCD). If the spectrum is too high or low, move the telescope slightly in RA (the RA- button moves the spectrum downwards in the image), iterate until the star is well positioned.
# Once you are happy with the position of the spectrum on the image, go back to the TCS and add a red marker over the position of the star on the slit (TCS ''Pointer'' pane: ''Markers'', ''Add a red marker'').
# Finally, move the guide fold mirror into the beam, and add a second red marker at the position of the star. This marker will be used to approximately position stars on the slit that are too faint to be seen reflected off the slit jaws.
* The red markers are lost if the TCS software gets restarted, so it is a good idea to note down their coordinates!