Array Observations

[Tom Droege <tdroege2@earthlink.net>]

I have been looking at the data where a star is moved around in position in 
the frame.

1) Processed stars are dimmer when measured in the center of the image than 
they are at the edges.

2) Dim stars are less distorted than bright stars.

The shape of the distortion is such that it suggests to me that the flat 
field is over applied.  I am still trying to think about how this might 
come about.

Hmmm! Stray light concentrating in the center of the image might do 
it.  This would make the flat too high in the center and cause the flat 
field to apply too large a correction there.  Dim stars are another matter.

I will soon get out data set 24.  Lots of fun to be had thinking up a good 
correction.  There is a very clear .2 mag variation to be gained for bright 
stars with a good scheme.

Tom Droege