Optical Variability of Blazars

In this paper we show the results of our monitoring the flux variability of 15 blazars, within the redshift range of 0.07 - 2.06, all with a visual magnitude range between 14 and 20 mag. Because blazars have displayed variability on diverse timescales, we have chosen to study them over both short and long timescales, ranging from minutes to years. These blazars were observed on 58 nights between 1995 March and 1998 June. Individual sources are discussed in detail. For example, one of our sources, Mrk 501, showed microvariability of as much as 0.13 mag change within 12 minutes. The usual parameters for size, mass, and luminosity are calculated. Relativistic beaming is implied by the data. We also searched for correlations between amplitude of variability, redshift, and luminosity. We found few, if any, such correlations. Discussion and conclusions are given for these and other results as implied by the data.