Weather Report for January 11, 2017

As is customary now in Arizona, the sky was full of thin cirrus at the start of the night. However, spectropolarimetry proceeded without much difficulty for the first two hours. This allowed multiple observations of CTA102 and three other blazars before they set. Then, thicker clouds moved in at around 2100 local time. The clouds, combined with bright moonlight, stopped operations until just after midnight. Sky conditions were reasonable, with some periods of completely clear skies, until nearly 0400 when more light cirrus combined with moonlight slowed operations down. The seeing was excellent during the first three-quarters of the night at about 1 arcsec. After that, it degraded to about 2 arcsec with short bursts of up to 3 arcsec. In all, over 15 blazars were observed and a little photometry was accomplished.