Re: Star's magnitude adjustments

[aah@nofs.navy.mil]

Mike G. wrote:
>...I don't remember making the above statement.  I too would be upset if
>the adjustment varied significantly unless the flat vector varied
>significantly.
  What you wrote earlier was:
>It really varies with the camera. Some show a parabolic shape with
>the end points about 0.05 to 0.10 mags above the minimum, some show
>minor fluctuations, others show a large slope with a difference of 0.25
>mags from one side to the other. Glenn and I are trying to see if the
>shape and values are consistent from one night to the next.
  I misread this by applying the last sentence to the previous ones. What
you stated was that each camera had a different correction, which would
make sense.
  Your linear interpolation within a lookup table for the corrections
is a good approach -- thanks for expanding your explanation of the technique.
  Creating a new flat vector every few nights or so, as you are doing,
is the right method.  I hope the other sites are doing the same.
  An interesting tid-bit.  We've been looking at geosync satellites here
with the IR camera, and they are quite bright.  There was a really neat
photo in one of the last Sky and Telescopes as well.  I wonder if some of
the high-frequency structure in the flatfield vectors could be due to
such satellites, since they would be trailed throughout the image in RA
but not much in DEC.
Arne