Quote:
Originally Posted by Shiraz
The PI scaling approach may be usable on variable sky flats as well, but it would possibly be stretching the friendship to try to extrapolate from normal darks. It would probably be better to use a set of darks taken at short exposures, more closely related to the sky flat exposures.
At least I think that is the case and I would happily be corrected...
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You are correct, Ray. Using "normal" darks to calibrate flats in PI tends to generate a lot of warning messages "no correlation between master dark and target frames". This is something which commonly freaks out new PI users
For calibrating lights, dark scaling works quite well so long as you're not using RBI pre-flash. With pre-flash you do need to match the light and dark integration times and disable scaling.
I do sky flats so the duration varies, but is typically short. Just calibrating my flats with a master bias (or better still, a super bias) works well.
Cheers,
Rick.