Possible Problem with the IR Flat Field

[Tom Droege <tdroege2@earthlink.net>]

As you all may know, I have been looking for the problem that might cause 
the Ic data to be funny as seen in TN-88.

I have discovered a problem with the flat field box.  (Michael R. will say 
"I told you so" and that is OK with me.  Just as long as I can improve the 
performance.) It appears that the black cardboard that I used to make it is 
transparent in IR.  So light is leaking in after the white cell.  This 
would cause the field not to be flat.

I sure hope that this is the problem as it is relatively easy to fix.  Just 
some new dark and flat frames.  My usual way to make flats was to do it 
with the tower doors closed in the daytime.  This makes the tower dark, but 
not pitch dark.  I will now do a set with the doors closed in the dark.  I 
will also cover the light box with tinfoil to really make it dark.

We shall see.

Tom Droege