TITLE: GCN CIRCULAR NUMBER: 15181 SUBJECT: GRB 130903A: Swift/UVOT Upper Limits DATE: 13/09/05 20:58:15 GMT FROM: Stephen Holland at STScI S. T. Holland (STScI) and Dirk Grupe (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of GRB 130903A starting 44.1 ks after the INTEGRAL/IBAS trigger (Mereghetti et al. 2013, GCNC 15169). We do not detect any new source consistent with the GROND afterglow position (Tanga et al. 2013, GCNC 15177) in any of the UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the summed exposures are presented below. --------------------------------------------------- Filter TSTART TSTOP Exposure Mag --------------------------------------------------- v 44,128 51,114 2461 >21.2 u 45,378 51,795 1442 >21.3 --------------------------------------------------- The quoted upper limits have not been corrected for the expected extinction due to the Galactic reddening along the line of sight to this burst of E(B-V) = 0.12 mag (Schlafly et al. 2011, ApJS, 737, 103).