Weather Report for October 16, 2012

A clear, productive night. The seeing was highly variable. Sometimes it was as good as 1.5 arcsec, at other times, around 2.5 arcsec or worse. It was fortunate that the exhaust clouds from category 3 hurricane "Paul" again stayed just south of the observatory all night long.

Observing was ended about an hour and half before the end of the night when it was realized that data quality was being compromised. Early diagnoses of the problem pointed to the shutter within SPOL either not opening all of the time or not opening completely. To inspect the shutter, the instrument needs to be partially disassembled, definitively ending the night. However, the shutter could not be coaxed into a failure when we could see it. Soon afterwords, it was discovered that a live moth had successfully crawled through the instrument from the telescope, past the shutter, and was found sitting atop the collimator lens (see the instrument schematic). As fate would have it, the instrument would have needed about the same level of disassembly to remove the moth. SPOL was reassembled in preparation for the coming night. Total time needed to correct the problem and reassemble SPOL was a little over 5 hours. Thanks go to Gary Schmidt for very fruitful long-distance consultations and to Grant Williams, who had joined in the observing during the night and helped in the resolution of this issue.