TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1476 SUBJECT: GRB 020813 Afterglow Observations; Possible break DATE: 02/08/13 13:34:58 GMT FROM: Josh Bloom at CIT GRB 020813 Afterglow Observations; Possible break J. S. Bloom (Harvard/CfA, Caltech), D. W. Fox (Caltech) and M. P. Hunt (Caltech) report: "Using the Palomar 200 inch + LFC, we observed the afterglow of GRB 020813 (GCN #1470) starting 06:49:50 August 13, 2000 UT, a little over four hours after the GRB trigger (GCN #1471). From that time, until 08:41:03 UT, preliminary photometry indicates that the OT faded by 0.30 +/- 0.02 mag in R(Steidel) band. A power-law decline in flux between these epochs was thus -0.75. Given the shallower decline reported from earlier epochs (-0.55, GCN #1474; -0.6, GCN #1473), the OT may have undergone a temporal break. We note that a break this early in the light curve is typical of high fluence, high energy events such as GRB 020813." This message may be cited.