MDM Trouble Report for 2014 Jun 18

Telescope: 2.4m
Observer(s): Thorstensen & Alper (D)
Instrument: modspec + echelle 

Problem(s) Encountered:
Eric spent much time yesterday dealing with the modspec shutter,
which was tending to stick open just a bit.  He got it 
running, apparently, but Paul found a spare which appeared to
be more reliable, so this ended up mounted just before it was
time for the staff to leave.

After the staff left I ran a sequence of 80 exposures of the MIS
flat-field lamp.  When I examined these I found that the 
exposure levels had varied by a factor of two or so -- usually
they are very consistent.  I assumed the shutter wasn't opening 
consistently, and removed the shutter assembly from the telescope
to visualize the shutter action.  It was working fine -- we 
couldn't make it fail. The flat exposures were about a minute
long, so I considered the possibility that the shutter was 
fatiguing and sagging shut after a bit, but it never flopped
shut in several longer tests. 

I called Eric and he suggested the flatfield lamp was not
consistent.  He suggested illuminating the slit jaws with 
the flat lamp and looking at them with the Andor -- and indeed,
when we did this, we found that the lamp was flickering 
quite a lot.  This is not at all typical, so there's something
wrong with it.  I should have good flats already, so it can 
be triaged out if something else urgent comes up.

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Submitted on 2014 Jun 19 [5:33:24]