Long-Term Optical Variability of Radio-selected Quasars from the FIRST Survey

We have obtained single-epoch optical photometry for 201 quasars, taken fromthe FIRST Bright Quasar Survey, which span a wide range in radio loudness.Comparison with the magnitudes of these objects on the POSS-I plates providesby far the largest sample of long-term variability amplitudes forradio-selected quasars yet produced. We find the quasars to be more variable inthe blue than in the red band, consistent with work on optically selectedsamples. The previously noted trend of decreasing variability with increasingoptical luminosity applies only to radio-quiet objects. Furthermore, we do notconfirm a rise in variability amplitude with redshift, nor do we see anydependence on radio flux or luminosity. The variability over a radio-opticalflux ratio range spanning a factor of 60,000 from radio-quiet to extremeradio-loud objects is largely constant, although there is a suggestion ofgreater variability in the extreme radio-loud objects. We demonstrate theimportance of Malmquist bias in variability studies, and develop a procedure tocorrect for the bias in order to reveal the underlying variability propertiesof the sample.Comment: 16 pages, 8 figures To be published in 2001 April 1 Astronomical Journa