2016ApJ...831....2B

We present the results of a recent reverberation mapping campaign for UGC 06728, a nearby low-luminosity Seyfert 1 in a late-type galaxy. Nightly monitoring in the spring of 2015 allowed us to determine an Hβ time delay of τ=1.4±0.8 days. Combined with the width of the variable Hβ line profile, we determine a black hole mass of M_BH=(7.1±4.0)×10⁵ M_☉. We also constrain the bulge stellar velocity dispersion from higher-resolution long-slit spectroscopy along the galaxy minor axis and find σ_*=51.6±4.9 km s^–1. The measurements presented here are in good agreement with both the R_BLR\mbox–L relationship and the M_BH\mbox–σ_* relationship for active galactic nuclei. Combined with a previously published spin measurement, our mass determination for UGC 06728 makes it the lowest-mass black hole that has been fully characterized, and thus an important object to help anchor the low-mass end of black hole evolutionary models.