More on the Curious Problem

[Tom Droege <tdroege@veriomail.com>]

Perhaps I did not make myself clear on the curious problem.  The pattern 
was of increased sensitivity.  I have seen dark spots on the CCDs before, 
and I can understand how they can come about.  Any little spot of stuff 
will do it.

Increased sensitivity in the 5-10% range is harder to understand.  If this 
is governed by process, and I saw an increase in sensitivity, then I would 
process the whole chip like that.  But perhaps it is a compromise, and one 
gets either uniformity or sensitivity.  Anyone know?

In any case, I changed out the I camera, and the new camera does not show 
the problem.  This one looks more like what I have become used to.  A 
little light in the corners.  No particular pattern.

BTW, the field looks quite flat.  I remember that the ROTSE people see a 
40% or so drop at the edges of the field.  I can see very little.  It is no 
more than 10% and probably less than that.  Once I get cameras out in the 
field I hope that you all will investigate things like this.

Tom Droege