MDM Trouble Report for 2014 Jan 23

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

Problem(s) Encountered:
I heard a loud bang from the telescope, which was almost 
certainly one of the mirror petals opening unexpectedly.

The circumstances were as follows.  I'd opened briefly at the
start, rotated the instrument to +85 for a target, failed to 
acquire in heavy cloud, and closed the mirror with the instrument
still rotated.  

Then it cleared after an hour or so, and +85 was still good for 
the target, so I went for it, and got a spectrum.  In my haste
to make use of the clear weather I hadn't checked that the 
mirror covers had all opened, since they pretty much always do,
and I was seeing actual light (!).  Then I went to another 
target which wanted +20 degrees, so I rotated the instrument
while slewing to the new target, which was maybe 2 hr W and a
little south of the equator.

As I was slewing and rotating the instrument, I heard a huge
bang which had the exact timbre of a stuck mirror cover
opening under pressure.  

That's all there was to it. It may be that the cover tends
to hang at odd rotator angles, and I rotated past the point 
where it was stuck.  

Incidentally, I certainly wouldn't have been trying to rotate
the instrument if I knew I had a stuck cover. 



------------------------------

Submitted on 2014 Jan 24 [6:06:13]