TITLE: GCN CIRCULAR NUMBER: 15093 SUBJECT: GRB 130812A: Swift/UVOT Upper Limits DATE: 13/08/13 16:15:52 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130812A 139 s after the BAT trigger (D'Elia et al., GCN Circ. 15088). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 15089) 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 u_FC 139 389 246 >20.3 v 445 12868 1191 >20.5 b 394 11236 1459 >21.7 u 139 7030 884 >20.8 w1 494 6825 491 >20.5 m2 469 6619 452 >20.3 w2 421 12142 1376 >21.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.23 in the direction of the burst (Schlegel et al. 1998).