Observational Factors Affecting Studies of Comet P/halley's Visual Light Curve

Over 5000 visual magnitude estimates of periodic comet Halley have been reported. These provide a data base for studying the factors which affect the distribution of visually estimated total magnitudes of comets. This preliminary study is based on observations made on eight selected days. It is concluded that scatter in the magnitude data is a function of (in order of importance) observer experience, comet morphology, and instrumentation used. Experienced observers generally report the brightest magnitude estimates.