Weather Report for September 20, 2015

This was a complex night of weather. During the late afternoon, the sky was overcast with thunderstorms to the south of Kitt Peak. By sunset, the sky was clearing rapidly with a couple of small thunderstorms to the southwest. Observations proceeded throughout most of the night, but were slowed or stopped on a several occasions as clouds quickly formed and dissipated over the mountain or moved in at higher levels from the northeast(!) to briefly aggravate the observer. After about 0200 local time, the sky finally cleared and both polarization and flux measurements could be obtained at the normal rate. In the end, it was a good night with well over a dozen blazars observed with most having a spectrophotometric measurement. The seeing, like the transparency, was variable (1-2 arcsec) and usually better near the end of the night.