TITLE: GCN CIRCULAR NUMBER: 6872 SUBJECT: GRB 071010A: Keck/LRIS Photometry DATE: 07/10/10 21:16:37 GMT FROM: Josh Bloom at UC Berkeley D. A. Perley, J. S. Bloom, M. Modjaz, and D. Poznanski (UC Berkeley) report: "In addition to the spectroscopic followup reported by Prochaska et al. (GCN 6864), we acquired imaging of the GRB 071010A field in g and R band with the Keck I 10m telescope (+LRIS) starting in twilight and continuing until the object set. The fading afterglow reported by Klotz et al. (GCN 6860) is well-detected. Photometry, calculated relative to the USNO B1.0 catalog, is as follows: t_start(min) R err 67.497 18.025 +/- 0.03 71.041 18.080 +/- 0.03 189.225 18.784 +/- 0.02 194.482 18.806 +/- 0.02 199.457 18.827 +/- 0.02 201.544 18.846 +/- 0.02 203.794 18.873 +/- 0.02 This photometry supersedes the preliminary report in GCN 6861 (Bloom et al.). In addition, starting at 213 minutes after the trigger we obtained a rapid series of 26 simultaneous g+R integrations of typically 30 sec duration, lasting until 239 minutes after the trigger. Analysis is ongoing." This message may be cited.