MDM Observatory 2.4m Telescope Observer's Report for 2008 Feb 23

Observer(s): John Thorstensen
Institution(s): Dartmouth (for Columbia)

Instrument: Echelle CCD direct + 4in FW

Worked for 10 hours (most of the night)
Conditions were Non-Photometric most of the night.
No equipment or software problems were encountered.

Seeing and Weather:
   Clouds from 4:30 until end.
   Beg: Seeing 1 arcsec, Cirrus, Winds Light & Variable
   Mid: Seeing 0.8 arcsec, Clear, Winds Light & Variable
   End: Overcast, Winds Light & Variable

Observing Summary:

Cirrusy in the afternoon, but most of the night was pretty clear,
approaching photometric at times.  The weather was very odd -
shortly after nightfall the ambient temperature began to climb,
eventually going from a low of 7 C to a high near 12, and the
dew point began to fall -- it went from about 0 (50 percent
humidity) down to -25 C (below 10 percent).  At the onset
of this the seeing was pretty bad but it soon got to be quite
good.  But then -- around 4:30 AM -- heavy altocumulus moved in, and
the guide star disappeared -- except for occasional glimpses
through the gaps in the cloud.  

I had one incident of the dome fugue state -- the dome
wandered by about 150 degrees (interrupting an exposure) before
it stopped and returned.  This is a known, but mysterious, bug
that manifests from time to time.  

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Submitted on 2008 Feb 24 [5:50:07]