MDM Observatory 1.3m Telescope Observer's Report for 2004 Feb 20

Observer(s): M. Bureau, M. Damen
Institution(s): Columbia University

Instrument: Direct imaging with Echelle

Worked for 5 hours (last half of the night)
Conditions were Mixed most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   Clouds from 18:30 until 00:30.
   Beg: Overcast, Winds Calm
   Mid: Seeing 2.0 arcsec, Cirrus, Winds Calm
   End: Seeing 1.8 arcsec, Cirrus, Winds Calm

Observing Summary:

The first half of the night was totally overcast and no data were obtained. It got better in the second half and we worked through mostly thin (and some patchy rather thick) cirrus. We increased our exposures times due to the lower transparency but decent data were acquired nevertheless (although with a seeing of 1.8-2.5 ).

We had major problems with the CCD during the first half of the night (luckily cloudy!). The bias level was highly non-homogeneous, with large patches of rows at hundreds of counts below or above the usual bias level. Various tricks did not solve the problem, but power cycling the CCD power supply with the help of Bob on the phone did it. The CCD behaved properly afterward.

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Submitted on 2004 Feb 21 [6:35:42]