MDM Observatory 2.4m Telescope Observing Report for 2011 Dec 04

Observer(s): Kevin Covey (PI: Agueros)
Institution(s): Columbia

Instrument: Modspec

Worked for 8 hours (most of the night)
Conditions were Non-Photometric most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   High Humidity from 3am until dawn.
   Beg: Clear, Winds Calm
   Mid: Clear, Winds Calm
   End: Fog/Low Clouds, Winds Calm

Observing Summary:

Opened at 6pm because the humidity dropped quickly after the sun 
set.  As I was taking cals, I noticed a bright blob in the middle 
of the flat field (ie, it wasn't very flat, and was noticably 
different than it had been in the previous nights of the run).  
I confirmed it was only there with the lamps on, and that moving
the mirror in and out didn't help.  I tried to clean the window 
to the dewar off with the nitrogen hose, but it didn't work, 
so it appears that something had frozen onto the dewar window 
(it was below freezing in the dome for most of the night).  
All told, didn't get really rolling till 8pm, but the good 
news is that the optical anomaly did go away over the course of the 
night.  

I lost pointing briefly at 11pm, but recovered it quickly by 
following the instructions in the observer's manual.  We then observed 
happily until 3AM, at which point the humidity had risen to 85%, 
so we closed.  The humidity continued to rise, to the point that 
the mirror temperature was becoming close to the dewpoint, so we
turned on the mirror heater as well.  

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Submitted on 2011 Dec 5 [4:18:36]