MDM Trouble Report for 2011 Apr 22

Telescope: 2.4m
Observer(s): Joe Shields, Fred Hamann (Ohio University, Univ. Florida)
Instrument: OSMOS

Problem(s) Encountered:
At 3 am after rotating the instrument we attempted to set
RA/Dec encoders with xtcs but due to operator error sent 
coordinates that were completely wrong.  Telescope was initially
at approx HA = 3 and began slewing spontaneously after encoders 
were set; slewing stopped, error message appeared on TCS monitor
that RA or Dec encoders not responding.  Inspection of the
telescope showed that it appeared to be at its western HA limit,
however the tcs monitor did not display a message about limit.
We attempted to back the telescope out of the limit using the 
standard procedure from the 2.4m manual and the telescope would
not move.  Much later we figured out that tcs was still 
attempting to execute a move which ceased when we clicked 
stop on tcs.  This made it possible to move the telescope with 
the hand paddle; evidently it had not yet hit the limit before 
something went wrong with the encoders.  I subsequently used 
the tiltmeters to bring the telescope to zenith and re-zero 
the pointing.  Telescope and tcs seem to be fine although
I don't understand why the telescope started slewing upon 
resetting the RA/Dec encoders.

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Submitted on 2011 Apr 23 [6:35:08]