== '''4. Observing''' ==
'''4.1 Arcs'''
At the start of an observation, take 2 arc exposures as follows:
1) Select “ND Pos 1”, “Mir Pos 3” and “Arc” in the QUARTZ “Control” panel
2) Click the “Expose” button in the “Control” panel on the right of the QUARTZ window and enter the exposure time. It is ok to saturate a few pixels of an arc exposure.
3) Switch on APD: click “APD” button in QUARTZ “Control” panel.
4) After readout, check counts on the image & in the QUARTZ info box on the bottom left. Counts should be as high as possible (<50000).
5) If satisfied, save to disk. Expose & save 2 arcs. Switch OFF “Arc”.
6) Switch OFF the APD when slewing/taking camera or fibre flats.
