MDM Observatory 2.4m Telescope Observing Report for 2010 Apr 20

Observer(s): Matthias Dietrich
Institution(s): OSU

Instrument: CCDS

Worked for 2.5 hours (first half of the night)
Bad weather most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   Clouds from 22:30 until 01:30.
   Beg: Seeing <1.5 arcsec, Clear, Winds Calm
   Mid: Seeing 2-3 arcsec, Cirrus, Winds Light &amp; Variable, high humidity 
   End: Cirrus, Winds Light &amp; Variable, high humidity

Observing Summary:

Around 22:30 high cirrus moved in and the brightest stars were 
only seen as faint, fuzzy patches. Beginning from midnight on
Mkn231 and Mkn684 were observed through clouds - sometimes the
target disappeared completely (clouds). At ~1:20 the humidity 
in the dome exceeded 85%. The telescope was stowed and the 
mirror covers were closed. At 1:40 also the dome was closed 
because also the outside humidity was above 85% and reached 
values of 92% for the rest of the night.
During the first two hours of the night I was observing. 
However, I noticed a problem with the auto guider. Even for 
bright stars and sufficient large guide boxes the guide probe 
started to oscillate and moved the guide star out of the guide
box. Hence, I guided by hand, like in the good old times.  
The pointing of the telescope was fine, within ~10 arcsec and
better.

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Submitted on 2010 Apr 21 [5:19:00]