Published online by Cambridge University Press: 12 April 2016
We present various methods for determining night quality from observations obtained with totally unattended automatic photoelectric telescopes at the Fairborn Observatory site on Mt. Hopkins, AZ. Telescopes are the Phoenix 10-inch (P10) and the Four College 75-cm (CAPT). Filter systems used are Johnson UBV, Kron-Cousins RI and Strömgren uvby. As a preliminary data filter for the P10 “rent-a-star” data, all observations with standard errors of the mean (SEM) above 20 mmag are discarded; a summary of nightly SEM’s, number of aborts and total observing time is sent to each user. The CAPT data are evaluated by standard deviation of magnitudes or counts for photometric groups and for an entire night. The Geneva photometric statistics are computed for these latter data and have proved useful as a preliminary screen for bad data. Various criteria for good and bad groups and nights are discussed. Scientific results are presented for several magnetic CP stars that were observed using both telescopes. Differences in precision of the data and strategies for observing are discussed.