2011MNRAS.416..225S

We present the results of our optical monitoring campaign of the X-ray source H 0507+164, a low-luminosity Seyfert 1.5 galaxy at a redshift z= 0.018. Spectroscopic observations were carried out during 22 nights in 2007, from 2007 November 21 to 2007 December 26. Photometric observations in the R band for 13 nights were also obtained during the same period. The continuum and broad-line fluxes of the galaxy were found to vary during our monitoring period. The R-band differential light curve with respect to a companion star also shows a similar variability. Using cross-correlation analysis, we estimated a time-delay of τ_cen= 3.01^+0.42_- 1.84_d (in the rest frame) of the response of the broad Hβ line fluxes to the variations in the optical continuum at 5100 Å. Using this time-delay and the width of the Hβ line, we estimated the radius for the broad-line region of 2.53^+0.35_- 1.55_{x} 10^–3 pc and a black hole mass of 9.62^+0.33_- 3.73_{x} 10⁶ M_☉.