Optical monitoring of southern quasars

A systematic programme to monitor optical activity in southern quasars was begun by the author in 1975, and is continuing. Because observations are in a non-standard (S20R) filter system, data reduction involves scaling observed iris photometer readings to plate-independent values. The relation between observed comparison star readings and a weighted mean value for each star is used to scale the quasar iris readings to a plate-independent but non-Pogson measure of apparent magnitude. This can be used to define variability into five groups. These are: rapid, large variations; rapid, small variations; slow, large variations; slow, small variations and no detected variations. An example of each type of light curve is presented. (author)