MDM Trouble Report for 2009 Sep 20

Telescope: 1.3m
Observer(s): S. Lepine (AMNH)
Instrument: MkIII + Nellie

Problem(s) Encountered:
At about 9pm, when moving to a new target, the
telescope abruptly stopped in mid-course. Attempts
to get it to move with a POINT command failed. Tracking 
could also not be restarted. After discussing the problem 
with Bob over the phone, we realized that the HA drive
appeared to be stuck. Motion is DEC was still possible
however.

After many attempts tinkering with the HA gear in the
south pillar, trying to move it manually, I finally managed 
to get it unstuck. It seemed then that the telescope could 
move west without problem, but not east. I tried adjusting 
the preloads until I could get the telescope to move normally 
both east and west. I then resumed observations.

I managed to observe for another 3 hours. However there 
were 4 instances where the telescope would stop again in 
mid-course; this seemed to happen whenever I would do a 
relatively large move in DEC. Every time I was able to 
resume the telescope motion just by using another POINT 
command.

At 2am however, the telescope stopped again in mid-course,
but this time apparently also losing data from the DEC 
encoder (no DEC value would show up on the TCS, even after
exiting and restarting the TCS session. Though I could get 
the telescope to track and move in HA, motion in DEC was no
longer possible. I also could not home the dome from the 
TCS, and had to do it manually.

Shut-down at 2:30am, telescope still pointing north.


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Submitted on 2009 Sep 21 [3:02:32]