OPTICAL CONTINUUM AND EMISSION-LINE VARIABILITY OF SEYFERT-1 GALAXIES

We present the light curves obtained during an 8 yr program of optical spectroscopic monitoring of nine Seyfert 1 galaxies: 3C 120, Akn 120, Mrk 79, Mrk 110, Mrk 335, Mrk 509, Mrk 590, Mrk 704, and Mrk 817. All objects show significant variability in both the continuum and emissi on-line fluxes. We use cross-correlation analysis to derive the sizes of the broad H beta-emitting regions based on emission-line time delay s, or lags. We successfully measure time delays for eight of the nine sources and find values ranging from about 2 weeks to a little over 2 months. Combining the measured lags and widths of the variable parts o f the emission lines allows us to make virial mass estimates for the a ctive nucleus in each galaxy. The virial masses are in the range 10(7) -10(8) M..