TITLE: GCN CIRCULAR NUMBER: 13011 SUBJECT: GRB 120305A: Swift/UVOT Upper Limits DATE: 12/03/06 17:55:47 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and G. Stratta (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120305A 72 s after the BAT trigger (Stratta et al., GCN Circ. 13004). No optical afterglow consistent with the enhanced XRT position (Beardmore et al., GCN Circular 13008) 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 initial finding chart (FC) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (FC) 72 221 147 >20.1 u (FC) 284 534 246 >20.4 white 72 6382 363 >21.1 v 5158 11729 1082 >19.7 b 540 18740 428 >20.4 u 284 24898 1918 >21.2 w1 5567 24288 1968 >20.7 m2 11734 23381 1740 >21.0 w2 6388 6584 193 >20.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.43 in the direction of the burst (Schlegel et al. 1998).