Optical Variations in Quasars

Abstract

A PHOTOGRAPHIC patrol of selected quasars has been in progress during the past 2½ years with the 40-inch telescope at Yale Observatory. We have already published¹ an account of the behaviour of one of the patrol objects, 3C 454.3. The purpose of this article is to summarize our results for other selected quasars in the patrol programme. The basic data are summarized in Table 1. The object designations are listed in the first column. In the second column, m denotes the approximate photographic magnitudes of the objects. In column three, A denotes the approximate maximum amplitude of the optical variations in magnitudes from our observations. Light curves for those quasars having variations ≈0.5 m, as well as for 3C 181, are shown in Fig. 1. Here photographic magnitudes relative to an arbitrary zero point have been recorded for all quasars other than 3C 345 due to the present lack of suitable standard sequences in the fields. While there is very little overlap between our patrol programme and that of Peach², in cases where overlap does occur (3C 181, for example) the light curves are in reasonable agreement. On each graph data points representing the “light curve” of a comparison star in the field are denoted by C. Error bars (p.e.) have been included in the graphs.