TITLE: GCN CIRCULAR NUMBER: 6306 SUBJECT: GRB 070419: P60 Confirmation of Optical Afterglow DATE: 07/04/19 11:16:54 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (Caltech) and D. B. Fox (Penn State) report on behalf of a larger collaboration: We have imaged the field of GRB070419 (Stamatikos et al., GCN 6302) with the automated Palomar 60-inch telescope. The candidate identified by Chornock et al. (GCN 5304) is visible in our images and variable; we therefore confirm it is the optical afterglow of GRB070419. Specifically, we measure the following R-band magnitudes: Mean Date Time Since Burst Magnitude -------------------------------------------------------------------------- 10:05:18 5.87 min 19.7 10:10:31 11.08 min 18.7 The above magnitudes were calculated assuming a magnitude of R=15.22 for the the USNO-B reference star located at 12:10:57.57, +39:55:40.2. Further observations are planned.