MDM Trouble Report for 2009 Feb 1

Telescope: 1.3m
Observer(s): Tom Brink (University of Michigan)
Instrument: 4K

Problem(s) Encountered:
On four consecutive images in the middle of the night strange 
features appeared on the ccd.  They are images ccd.0594.fits 
through ccd.0597.fits.  Images 594 and 595 have a dark rectangle 
running vertically down the middle of the ccd.  The counts are
lower by 100-150 within the rectangle.  Images 596 and 597 have
the same rectangle, and also have a very noisy pattern in the 
lower right hand corner.  The preceding (593) and following (598)
images appear fine.  The exposure times for the images were 7 
minutes each (plus 2 minutes to readout); so the problem occurred 
over a span of about 36 minutes. I have no idea what caused these 
strange features to appear and disappear.

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Submitted on 2009 Feb 2 [7:39:44]