MDM Trouble Report for 2011 Aug 24

Telescope: 1.3m
Observer(s): Jules Halpern (Columbia U.)
Instrument: R4k

Problem(s) Encountered:
I am using the R4k in unbinned 1kx1k mode, and it has some 
undesirable features.  First, the bias has structure in which
the columns alternate by more than 1000 counts in one quad,
the other quads having a similar pattern of lower amplitude.
This does not subtract completely.  It makes it difficult to
examine an image, e.g. for focus stars, without first
subtracting the bias.  Second, there are bunches of very
bad rows.  The worst quadrant is the northeast one. 
It's difficult to describe all of these effects, so I have 
made a collection of images for any interested party to look at.
They comprise one bias and three object images.
A 6.5 Mb gzipped tar file is here:
http://www.astro.columbia.edu/~jules/R4k.tar.gz



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Submitted on 2011 Aug 25 [4:09:34]