Standstill Behavior In The Light Curve Of UZ Serpentis Orville H. Brettman Rivendell Foundation Hemmingsen RD. Huntley, Illinois Electronic mail:

ABSTRACT days of observations of UZ Serpentis are discussed. Numerous instances of standstill behavior are analyzed and the argument advanced for the reclassification of UZ Serpentis

History UZ Serpentis was discovered variable by Reinmuth at Konigstuhl in 1924 Parenago using the Moscow plates found that its variation resembled that of the irregular variables known as U Geminorum stars. Herbig reports that Parenago found intervals between successive maxima to be between 20 and 36 days. Visual estimates of this range reported by Koyama et.al.during indicated that the interval between outbursts were on the order of 19 – 32 days, and Herbig and others from the AAVSO found intervals to vary between 9 and 22 days. Based on absolute visual magnitude studies of U Geminorum and SS Cygni conducted by the Gaposchkins and arguing from color magnitude estimates of Gerasimovic and Payne Herbig argued for the classification of UZ Serpentis as a U Geminorum star.

Standstills The Plot thickens Dyck published a paper in the Journal of the AAVSO in January of 1988 first calling attention to standstill behavior, which he had observed during the 1987 observing season. He noted that UZ Serpentis appeared to standstill in brightness for a period of approximately 6 months form May to October of 1987 when normal outbursts reoccurred. Dyck again published in the Journal of the AAVSO in February of 1990 calling attention to yet another episode of standstill behavior in the 1989 apparition of UZ Serpentis. He also noted what he called a Significant brightening of the system toward the end of the standstill.

The Data The author began an investigation of the intermediate term behavior of UZ Serpentis in the summer of 2001 with the aid of observations of the magnitude of UZ Serpentis over nine whole and two partial apparitions of the variable, a period of 3444 days. The vast majority of the observations are visual with the remainder being CCD V band observations. All data points were provided by Janet Mattei, Director of the AAVSO, and the author is in her debt and that of the AAVSO for the provision. The data is presented here as 11 separate figures each represent the points of a given apparition. The very first data point was recorded on May 23, 1991 and the last was recorded on May 31, 2001.