MDM Trouble Report for 2006 Mar 21

Telescope: 1.3m
Observer(s): chris peters (dartmouth college)
Instrument: mark III + templeton

Problem(s) Encountered:
While following an object called at RA 09 46 and 
Dec +13 50 to an airmass of 3.3, the telescope 
became oriented such that the dewar came in contact with 
the liquid nitrogen tank.  When I went to move the 
telescope to the next object, I noticed that this was 
the case.  I started to slew the telescope to the 
next object, and the telescope moved such that 
the dewar became caught on the tank.  Instead of moving the 
telescope in reverse away from the tank (as would have 
been the right thing to do), I went and dislodged it 
by hand.  When I did this, there was no odd 
sound, nor sign of damage 
to the dewar itself, so I didn't know at the time that 
anything was wrong.

The next object was very faint, and when I took a long 
exposure (15 minutes) and didn't see the spectrum that I was 
expecting, I assumed that I hadn't centered the 
object correctly in the slit.  So I recentered and tried 
again, with the same result.  Confused, I moved to a 
bright star, one that I was sure that I could get in the 
slit.  I took an appropriate exposure, and the spectrum 
still did not appear correct.  It was at this moment, about 
45 minutes after I had dislodged the dewar, that 
I began to realize that something had been corrupted.  

I went into the dome to look at the telescope, and 
noticed that the dewar had a layer of frost all over it.  
Having never seen this before, I knew that this was 
not good.  I called up to Prof. Thorstensen at the 2.4-m, 
and given the symptoms, he diagnosed the problem 
that the vacuum in the dewar to become corrupted, 
and so the CCD warmed up.

I'm really sorry in advance for the trouble this is going 
to cause later today. 

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

Submitted on 2006 Mar 21 [6:14:57]