Re: flats (was: Good Board Stack)

[Arne Henden <aah@nofs.navy.mil>]

Also, another reason for taking flats frequently is to randomize
any systematic error they may cause.  If your monthly flats
have some problem, then that problem will be applied to all
observations from that month.
   I am surprised that you have given up with lightbox flats.
The most flat illumination you can get is from an integrating
sphere, and that should be easy to construct for a 10 cm aperture.
You should look into that.  Having to worry about neighbor's
lights and clouds is a real pain and a likely source for error.
LOTIS found that their best flats came from foggy nights, where
there was no structure to the clouds; you might find "cloud flats"
to be your best flats if you don't want to go with an integrating
sphere.  Just average lots of them together.
   But you say you have no problems with flats, and they are usable
month after month.  Ok, then ignore my comments.
Arne