Program: GN-2010B-SV-165

Black hole masses for large samples of active galactic nuclei (AGN) are estimated from single-epoch optical spectra. In particular, the two quantities needed for a black hole mass calculation, namely, the velocity and the radial distance of the orbiting material are derived from the widths of the Balmer hydrogen broad emission lines and the optical continuum luminosity, respectively. However, this method suffers from severe problems: the observed optical continuum is often contaminated by host galaxy starlight and so does not measure only the ionising flux, the optical hydrogen broad emission lines are strongly blended with other species (such as FeII), and optical measures can suffer from dust extinction. We have recently found a near-IR relation for estimating AGN black hole masses that circumvents these problems. It is based on the widths of the Paschen hydrogen broad emission lines and the continuum luminosity at 1 micron. Here we propose to measure these two quantities in 14 AGN with black hole masses known from reverberation studies. The observations will considerably improve the number statistics in our relation, which we plan to publish shortly.