TITLE: GCN CIRCULAR NUMBER: 15229 SUBJECT: GRB 130912A: Swift/UVOT Upper Limits DATE: 13/09/15 20:52:11 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130912A 99 s after the BAT trigger (D'Elia et al., GCN Circ. 15212). No optical afterglow consistent with the enhanced XRT position (Beardmore et al. GCN Circ. 15217) 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) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 99 249 147 >20.7 u_FC 311 561 246 >20.2 white 99 6848 785 >21.4 v 640 23984 1395 >20.3 b 566 30470 1907 >21.6 u 311 36236 3907 >21.6 w1 690 35508 3836 >22.1 m2 1070 34601 2827 >21.8 w2 616 23070 1376 >21.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.28 in the direction of the burst (Schlegel et al. 1998).