Problem(s) Encountered:

Noticed bands of elevated background noise at the top and bottom of the image (somewhat shaped like a negative of an hourglass). Most noticeable when taking long darks or images of dark patches of sky. Attempts to block light leaks had no effect. We noticed the pattern was also present in the bias frames, so we restarted the IC computer and the data taking taking software. After the first power cycle, we noticed new horizontal fringes in part of the bias frame. After two power cycles the effect decreased in magnitude but was still noticeable in bias and dark images.

Solution:

I’ve started everything from scratch, including recabling the detector.  Things look ok, but I don’t know that the problem would be visible in daylight anyways.  Not much more I can check but we’ll likely know if things have improved once the sun sets.