MDM Trouble Report for 2024 Jun 10

Telescope: 2.4m
Observer(s): John Thorstensen (Dartmouth)
Instrument: OSMOS

Problem(s) Encountered:
For the last object of the night I set on a standard star at
dec +28 degrees and near the meridian.  I slewed there as
usual and moved the guide stage into position for a bright
guide star, and then -- the telescope did not settle.  Instead
it bobbed north and south by about +- 5 arcmin - I could see
the guide star flying through the field -- with a period of maybe
5-10 seconds.  I hit the red stop sign in the TCS window and it
stopped, and then manually set the dec by pulling the guide star
into where it was supposed to be.  While I was doing this, I 
noticed that the dec displayed in the TCS window was not updating
and I feared the dec readout had failed.  I acquired the 
guide star and target, and took a spectrum.

It was time to stow the telescope, so I disengaged the autoguider,
set the track rate to zero, and sent the telescope to the zenith.
To my great relief, it went right to the zenith with the dec 
readout incrementing in the normal way, so apparently my worst
fears were not realized.  I can't recall ever seeing the DFM 
system do anything like this. 

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Submitted on 2024 Jun 11 [5:26:29]