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  A list of Faint and Bright (for 3 tex2html_wrap_inline1109 m) IR UKIRT standards can be found in Appendix D. The positions of these standards are also loaded into the default WHT standards catalogue. Typical exposure times for most of these will be 1-3 secs, and you should of course take each standard exposure through each filter used on your programme objects. At the very minimum you should take 3-4 standards at the beginning and end of the night and 2-3 in the middle, and it is always a good idea to take 1-2 throughout the night, every 1-3 hours, to monitor the sky conditions (especially true if there is any dust around, or the possibility of cirrus). You should also aim to observe at least one standard over as large a range of airmass as possible, so you can derive extinction coefficients for each night, as these may change depending on how much dust is around.

And don't forget to take your standards in a series of dithered exposures, to allow accurate removal of sky and cosmic rays, and to remove all the hot pixels!

Shaun Hughes
Thu Mar 14 14:48:38 GMT 1996