MDM Observatory 2.4m Telescope Observer's Report for 2003 Apr 17

Observer(s): eve armstrong
Institution(s): columbia

Instrument: echelle

Worked for 10 hours (most of the night)
Conditions were Mixed most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   High Humidity from 21:00 until 22:00.
   Beg: Seeing 6 arcsec, Cirrus, Winds Moderate
   Mid: Seeing 6 arcsec, Clear, Winds Light & Variable
   End: Seeing 6 arcsec, Clear, Winds Calm

Observing Summary:

There seems to be an astigmatism.  I had an impossible time focusing
tonight.  The best i did was about 6 arcseconds.  A focus change of more 
than 5 increments in either direction caused the stars to become
triangular.  i've never seen this before.  the guider wasn't 
occulting the ccd (as far as the diagrams are concerned, at least),
and neither was the dome.

i was testing within the same focus range as i'd used last night.
the seeing last night wasn't great either ( ~ 3 ), but i 
certainly didn't have this problem.  out-of-focus images were
doughnut-shaped, not triangular.

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Submitted on 2003 Apr 18 [4:30:55]