We present the final installment of an intensive 13-year study of variations of the optical continuum and broad Hβ emission line in the Seyfert 1 galaxy NGC 5548. The data base consists of 1530 optical continuum measurements and 1248 Hβ measurements. The Hβ variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, r ∝ L 1/2 ion . Moreover, the apparently linear nature of the correlation between the Hβ response time and the nonstellar optical continuum F opt arises as a consequence of the changing shape of the continuum as it varies, specifically F opt ∝ F 0.56 UV .

Abstract. We present results of a variability campaign of Mrk 110 performed with the 9.2-m Hobby-Eberly Telescope (HET) at McDonald Observatory. The high S/N spectra cover most of the optical range. They were taken from 1999 November through 2000 May. The average interval between the observations was 7.3 days and the median interval was only 3.0 days. Mrk 110 is a narrow-line Seyfert 1 galaxy. During our campaign the continuum flux was in a historically low stage. Considering the delays of the emission lines with respect to the continuum variations we could verify an ionization stratification of the BLR. We derived virial masses of the central black hole from the radial distances of the different emission lines and from their widths. The calculated central masses agree within 20%. Furthermore, we identified optical He i singlet emission lines emitted in the broad-line region. The observed line fluxes agree with theoretical predictions. We show that a broad wing on the red side of the [O iii]λ5007 line is caused by the He i singlet line at 5016Å.

We present the results of 3 yr of ground-based observations of the Seyfert 1 galaxy NGC 5548, which, combined with previously reported data, yield optical continuum and broad-line Hb light curves for a total of 8 yr. The light curves consist of over 800 points, with a typical spacing of a few days between observations. During this 8 yr period, the nuclear continuum has varied by more than a factor of 7, and the Hb emission line has varied by a factor of nearly 6. The Hb emission line responds to continuum variations with a time delay or lag of D10È20 days, the precise value varying somewhat from year to year. We Ðnd some indications that the lag varies with continuum Ñux in the sense that the lag is larger when the source is brighter.

Abstract.We recorded spectra of the highly variable Seyfert 1 galaxy Mrk 110 in a variability campaign with the 9.2 m Hobby-Eberly Telescope at McDonald Observatory in order to study the detailed line profile variations of the broad emission lines. Here we show that only an AGN model predicting the formation of the broad Hβ line emission in the wind of an accretion disk matches the observed 2-D variability pattern. Furthermore, we derive an improved mass of the central supermassive black hole of M = 1.07 M from the Hβ velocity-delay map.

We report on the results of a 5 year coordinated program of spectroscopic monitoring of the luminous Seyfert 1 galaxy Markarian 509. The Hb and He II j4686 emission lines are found to respond to continuum variations with time lags of D80 and D60 days, respectively, considerably longer than the emission-line lags measured for other Seyfert galaxies.