Subject: stray light in GRIM

From: likkel@delta.math.wsu.edu

Submitted: Wed, 24 Jul 96 11:04:40 -0700

Message number: 22 (previous: 21, next: 23 up: Index)

Using GRIM last night I noticed 4 blobs (spots) on the GRIM images
that I hadn't noticed.
They show up well after subtracting a dark (e.g. ngc6572.0017 - dark.0010);
and look like stars in mediocre seeing conditions.
Eddie pointed out that these are not bad pixels, but must be
reflected light. One of the blobs is bright and distinct, the other 3 are
dim and show up centered on the same row but centered on different columns.

They show up in spectra as well as images.
Although these blobs don't subtract out with the dark, they seem to
subtract out well when subtracting an offset-position from an on-position.

--Lauren Likkel
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