MDM Observatory 2.4m Telescope Observing Report for 2016 Oct 22

Observer(s): Frank & Swihart
Institution(s): OSU & MSU

Instrument: OSMOS

Worked for 13 hours (all night)
Conditions were Mixed most of the night.
No equipment or software problems were encountered.

Seeing and Weather:
   Clouds all night.
   Beg: Seeing 1.2 arcsec, Patchy Clouds, Winds Light & Variable
   Mid: Seeing 0.8 arcsec, Patchy Clouds, Winds Light & Variable
   End: Seeing 0.8 arcsec, Patchy Clouds, Winds Calm

Observing Summary:

We were able to take some good data despite the whole area being engulfed in at times heavy clouds.
Neither hard- nor software problems encountered.

However, we noticed the following in a few frames :
there is a large dark circular region in the image that seems to start
at image 0133 from the night of 21_10_2016. It is not the chip that is affected 
since readouts for bias, lamps, science spectra are not affected. The center of 
the dark region is at 700 / 600 in the 4x1K readout, and affects the flux until
~1600 in x. It also appears not be symmetric wrt to its center.
After occurring in about 20 frames, this feature vanished subsequently without any
of our intervention.

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Submitted on 2016 Oct 23 [5:21:24]