MDM Observatory 2.4m Telescope Observer's Report for 2006 Aug 28

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

Instrument: echelle CCD + 2in FW

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

Seeing and Weather:
   Beg: Seeing 0.9 arcsec, Clear, Winds Light & Variable
   Mid: Seeing 0.6 arcsec, Clear, Winds Light & Variable
   End: Seeing 0.7-2 arcsec, Patchy Clouds, Winds Light & Variable

Observing Summary:

A good night, mixed program of parallaxes and various other
exposures.  Lightning visible very far to SE, some cirrusy
debris may have drifted over, but generally clear enough to
risk photometry esp. in the north.  Seeing was really superb 
most of the night, getting down to just below 0.6 arcsec from 
time to time, but a bubble of cooler and more humid air came 
over from 2 to 3 AM which obliterated the good seeing for a 
while - but then it was gone!

The equipment generally behaved itself, but I noted the 
following non-critical problems; I'm not filing a trouble
report, because these are so non-critical and since I lost
no time.

a) The detector temp was -89 C before I filled in the evening,
vapor was coming out of the dewar and it looked normal other-
wise.  After I filled it the temperature drifted down only
very slowly, by about a degree in half an hour or so. At the
end of the night the temp was -95 C (I was too busy to check
it through the night).  It's possible the dewar was running
out of LN2 at both the beginning and end, but it seems more
likely that the chip is running a little hot for some reason.

b) The telescope had a couple of glitches.  A few times it
got into the set/slew oscillation during auto-set -- this
seems to happen with the telescope about 2 minutes of time
west of the target.  The cure is software stop, followed by
manually setting closer to the target, followed by autoset,
which then proceeds normally.

c) On a couple of occasions I noted some relatively rapid
drift during open-loop tracking (not guiding).  The telescope
slipped by about 15 arcsec with respect to the sky over 
about a minute or so, in the sense that the tracking was too
slow. Intermittent and I'm sure hell to diagnose, and I think
it's new.

d) One time (at least) during an auto-set the telescope was
slowly crawling into the target using a guide-like rate from
quite a ways out (many arcmin).  Again, software stop followed
by manual intervention solved the problem.

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Submitted on 2006 Aug 29 [6:17:14]