Re: I Camera Flatness

[hjohnson@pluto.njcc.com (Herbert R Johnson)]

I hope my colleagues would excuse me for commenting on this subject,
although I am not following this particular thread in detail. I see
there is some discussion of what I might call "edge effects" on the
mark IV images. SOmeone might review some of my earlier work on
Mark IV dark images, on the early disks that Tom released before
he improved cooling. I saw patterns of brighter pixels along some
edges, and extending tens of pixels into the images. I speculated
on what these might be about. This information or the methods used
may be helpful for current images.

The appropriate Tech Note should be apparent from
the title. While in principle effects in both darks and images should
subtract out, in practice there may be either increased noise toward
the edges, or occasions where this particular set of effects do NOT
cancel out. Any discussion of it I might make, would already be in
the Tech Notes. If current discussion leads to anything that I might
change in the Note, please contact me directly so I can change or
amend it, I am pleased to do so.

Herb Johnson

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