The Lick AGN Monitoring Project 2011 observing campaign was carried out over the course of 11 weeks in Spring 2011 .
Here we present the first results from this program , a measurement of the broad-line reverberation lag in the Seyfert 1 galaxy Mrk 50 .
Combining our data with supplemental observations obtained prior to the start of the main observing campaign , our dataset covers a total duration of 4.5 months .
During this time , Mrk 50 was highly variable , exhibiting a maximum variability amplitude of a factor of \sim 4 in the U -band continuum and a factor of \sim 2 in the H \beta line .
Using standard cross-correlation techniques , we find that H \beta and H \gamma lag the V -band continuum by \tau _ { \mathrm { cen } } = 10.64 _ { -0.93 } ^ { +0.82 } and 8.43 _ { -1.28 } ^ { +1.30 } days , respectively , while the lag of He ii \lambda 4686 is unresolved .
The H \beta line exhibits a symmetric velocity-resolved reverberation signature with shorter lags in the high-velocity wings than in the line core , consistent with an origin in a broad-line region dominated by orbital motion rather than infall or outflow .
Assuming a virial normalization factor of f = 5.25 , the virial estimate of the black hole mass is ( 3.2 \pm 0.5 ) \times 10 ^ { 7 } { M } _ { \odot } .
These observations demonstrate that Mrk 50 is among the most promising nearby active galaxies for detailed investigations of broad-line region structure and dynamics .