TITLE: GCN CIRCULAR NUMBER: 13206 SUBJECT: GRB 120403B: Swift/UVOT Upper Limits DATE: 12/04/04 11:35:55 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (MSSL-UCL) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120403B 911s after the BAT trigger (D'Elia et al., GCN Circ. 13203). No optical afterglow consistent with the XRT position (Goad et al., GCN Circ. 13205) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 911 1061 147 >21.7 white 1190 7931 568 >22.0 v 1068 8342 588 >20.7 b 1166 7726 568 >21.3 u 1141 12488 404 >21.1 w1 1117 9020 851 >21.1 m2 1092 8547 568 >20.8 w2 1216 8137 485 >21.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.13 in the direction of the burst (Schlegel et al. 1998).