We present the first results from the Las Cumbres Observatory Global Telescope ( LCOGT ) Network ’ s Active Galactic Nuclei Key Project , a large program devoted to using the robotic resources of LCOGT to perform time domain studies of active galaxies .
We monitored the Seyfert 1 galaxy Arp 151 ( Mrk 40 ) for \sim 200 days with robotic imagers and with the FLOYDS robotic spectrograph at Faulkes Telescope North .
Arp 151 was highly variable during this campaign , with V -band light curve variations of \sim 0.3 mag and H \beta flux changing by a factor of \sim 3 .
We measure robust time lags between the V -band continuum and the H \alpha , H \beta and H \gamma emission lines , with \tau _ { \mathrm { cen } } = 13.89 ^ { +1.39 } _ { -1.41 } , 7.52 ^ { +1.43 } _ { -1.06 } and 7.40 ^ { +1.50 } _ { -1.32 } days , respectively .
The lag for the He ii \lambda 4686 emission line is unresolved .
We measure a velocity-resolved lag for the H \beta line , which is clearly asymmetric with higher lags on the blue wing of the line which decline to the red , possibly indicative of radial inflow , and is similar in morphology to past observations of the H \beta transfer function shape .
Assuming a virialization factor of f =5.5 , we estimate a black hole mass of M _ { \mathrm { BH } } = 6.2 ^ { +1.4 } _ { -1.2 } \times 10 ^ { 6 } M _ { \odot } , also consistent with past measurements for this object .
These results represent the first step to demonstrate the powerful robotic capabilities of LCOGT for long-term , AGN time domain campaigns that human intensive programs can not easily accomplish .
Arp 151 is now one of just a few AGN where the virial product is known to remain constant against substantial changes in H \beta lag and luminosity .