MDM Trouble Report for 2001 Apr 30

Telescope: 2.4m
Observer(s): Brad Peterson, Laura Ferrarese, Chris Onken (Ohio State, Rutgers)
Instrument: CCDS

Problem(s) Encountered:
About 1 am we noticed some odd structure on the chip as we read
it out. Nothing obviously wrong, but we found that we had
apparently lost cooling, temperature of dewar reading
about -60. We tried refilling the dewar, and it overflowed
quickly, suggesting that the dewar was in fact not empty.
Temperature did decrease to about -65 after about 5 minutes.
After about 45 minutes (too late to get any additional data
tonight), the dewar was back at operating temp (about 3:30 am).

Our conclusion was that dewar was not filled at the beginning
of the night, most likely because of our error, but possibly
because of the fill tube. This still does not explain why the
dewar refilled so quickly. Note: this is NOT the fill tube that
was giving us trouble at the beginning of the run.


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Submitted on 2001 Apr 30 [3:24:05]