FIRST RESULTS FROM THE LICK AGN MONITORING PROJECT: THE MASS OF THE BLACK HOLE IN ARP 151

We have recently completed a 64 night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 13 nearby (z < 0.05) Seyfert 1 galaxies with with expected masses in the range similar to 10(6)-10(7) M(circle dot). We present here the first results from this project-the mass, of the central black hole in Arp 151. Strong variability throughout the campaign led to an exceptionally clean H beta lag measurement in this object of 4.25(-0.66)(+0.68) days in the observed frame. Coupled with the width of the H beta emission line in the variable spectrum, we determine a black hole mass of (7.1 +/- 1.2) x 10(6) M(circle dot), assuming the Onken et al. normalization for reverberation-based virial masses. We also find velocity-resolved lag information within the H beta emission line which clearly shows infalling gas in the H beta-emitting region. Further detailed analysis may lead to a full model of the geometry and kinematics of broad line region gas around the central black hole in Arp 151.