MDM Trouble Report for 2008 Jun 28

Telescope: 2.4m
Observer(s): John Thorstensen (Dartmouth)
Instrument: modspec + echelle CCD

Problem(s) Encountered:
During twilight I was guiding on an object at HA = 4h09m East, 
and dec = +29, and the telescope suddenly jumped east by about
30 arcsec.  I was watching and was able to quickly get the star
back in the slit, so no time was lost.  Later in the evening
the telescope successfully tracked through the same eastern
hour angle, but up at dec = +42 degrees, so the glitch does
not always recur at the same hour angle.  I'm reasonably sure
that nothing was sitting on the paddle at the time (if a guide
command is issued when the set button is pushed, the telescope
will obviously jump, but I don't believe that was the case
here).  It reminded me a little of the drive problem that was 
later linked to the cracked bearing, but in that case, when 
the problem occurred, it would go on for several minutes.  By
contrast, this was a one-time event.    

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Submitted on 2008 Jun 29 [4:08:06]