MDM Observatory 1.3m Telescope Observing Report for 2011 Aug 23

Observer(s): Jules Halpern
Institution(s): Columbia U.

Instrument: R4K

Worked for 5.5 hours (part of the night)
Conditions were Non-Photometric most of the night.
No equipment or software problems were encountered.

Seeing and Weather:
   Clouds all night.
   Beg: Overcast, Winds Light & Variable
   Mid: Seeing 1.5 arcsec, Cirrus, Winds Light & Variable
   End: Overcast, Winds Light & Variable

Observing Summary:

It appears that Richard Treffers has fixed the N-S oscillation.
That's a great relief.  I am observing without an autoguider,
so I haven't been able to check the guiding. The tracking is not
perfect, so exposures longer than about a minute are trailed.
The default rate is too fast by about 0.045 seconds of time per
minute.  I'm trying to optimize the tracking rate, but there is 
even a drift to the North by about 0.2 arcseconds per minute.  

The new issue, which I was warned about, is the focus control.
The focus motion is very sticky and/or it overshoots.  It used
to be possible to focus to within one unit or better, but now
focusing is very tedious and can only be achieved with luck.
Normally I would bump the focus on the fly, between exposures,
but now that is impossible.

I was only able to do a limited number of pointings due to
clouds, so I will delay commenting on the reliability
of the slewing and dome motion.  I was advised to home the
dome manually, and to make sure that the dome is centered
on the telescope.

The new R4K CCD has a strong vertical pattern, which is worse
in certain quadrants.  I presume that it is stable and that
bias frames will subtract it.  Otherwise, it will be useless.
I will check that tomorrow.

------------------------------

Submitted on 2011 Aug 24 [4:42:31]