A few notes

• Morning / afternoon calibrations: Flats in different IR filters require time, in particular with narrow band filters. Please organize everything in advance with the SA and OA, especially if you need flats on the sky. In normal circumstances the dome has to be accessible to the daycrew from 08:00am to 05:00pm, monday to friday, so please be aware that telescope operations may conflict with your requests. The SA will also let you know what calibration data are already available from previous observers.

• Staring or not?: CFHT-IR can be used without closing its warm shutter, in what is called its "staring mode", selected by "staring 1" in the detector window (or in an observing script). The exposure time of staring mode exposures is always a multiple of the readout time (enforced by the acquisition program), and must be at least twice the readout time. The staring mode has reduced overheads (no shutter cocking), and eliminates the thermal background from looking at the warm shutter during readout (~800ADUs for K, ~500 ADUs for K'). It also has more accurate timing than the mechanical shutter. It is the recommanded observing mode, unless you need exposure times below one second.

• Make sure you use the blank filter position when obtaining darks. The cfhtir shutter is WARM, and a very significant source of thermal radiation (500 ADU/s with the K' filter, 800 ADU/s with the K filter, for typical dome temperatures of a few degrees Celsius). K band exposures on the shutter saturate in about 1~mn...

• The detector exhibits a memory of having been saturated, that will affect the next few subsequent exposures. This can for instance happen when obtaining flat-field exposures with too long integration times, or while observing bright sources. A cube of 8 0.1 second exposures second is usually sufficient to clean the detector (unless you saturated it really badly, and many times). Script detclean will do that for you

• File names: Changing the acquisition directory from the default (/data/piko/cfhtir) is NOT recommanded: it adds an extra 4s to the readout overhead to access a non-local disk. Files are automatically copied to ~cfhtir/images after a few seconds.
  You are NOT allowed to change the filename ######x.fits (constraint due to archiving). An odometer will automatically incremement this number. After an integration, the name that appears in the DetI form is the filename for the next exposure, NOT the one that just finished.