MDM Observatory 1.3m Telescope Observing Report for 2010 Feb 12

Observer(s): Warren Brown
Institution(s): SAO

Instrument: Echelle CCD

Worked for 10.5 hours (all night)
Conditions were Photometric most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   Beg: Seeing 1.5 arcsec, Clear, Winds Calm
   Mid: Seeing 2.0 arcsec, Clear, Winds Calm
   End: Seeing 1.5 arcsec, Clear, Winds Calm

Observing Summary:

Great night, with one issue: the guider.  When pointing east (HA<-3 hr)
at the beginning of the night I experienced the north-south guider
oscillation problem.  Every couple minutes a large >1 arcsec guider
correction would appear while tracking.  Looking at the guide camera,
it was clear that an additional one or two seconds would elapse before the
telescope would move, during which time an additional one or two large
corrections would be called (because the telescope had not moved yet).
At this point, the guider would call a couple large corrections in the
opposite direction.  If I did not stop the guiding immediately, the
guider would oscillate the star out of the guide box.  When star left
the guide box, the telescope tracking would turn off.  I conclude that
the time constant for correcting the N-S motion is wrong, at least for
HA<-2.5 hr.  I did not experience this problem anywhere else on the sky
HA>-2.5 hr.

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Submitted on 2010 Feb 13 [5:09:28]