2011MNRAS.410.1877S

We present further results of the optical observations of the 3C 390.3 nucleus undertaken at the Crimean Astrophysical Observatory since 1992. From the new data obtained in 2000–2007, we find differences in the responses of the Balmer emission lines to the optical continuum variations. Moreover, these responses (i.e. the relationship between line and continuum fluxes) show long-term changes that can be presumably attributed to the evolution of the relationship between the fluxes of the optical and driving continua. We suspect that some small discrepancy between our spectral and photometric measurements of 3C 390.3 can be attributed to the long-term variability of the [O III] λ 5007 Å forbidden line. The cross-correlation analysis of the light curves let us to improve the values of the time delays between continuum and emission-line variations: τ_cent= 94±6 and 174±16 d for the Hβ and Hα lines, respectively. The black hole mass, derived from the Hβ line, was found to be 2.0 {x} 10⁹ M_☉. This result suggests an even larger black hole mass for the 3C 390.3 nucleus and, therefore, a lower accretion rate under a given luminosity than was previously thought and thus it provides more evidence for anticorrelation between broad-line widths and Eddington luminosity ratios L_bol/L_Edd in AGNs.