TITLE: GCN CIRCULAR NUMBER: 18660 SUBJECT: GRB 151205A: Swift/UVOT Upper Limits DATE: 15/12/05 23:00:57 GMT FROM: Lea Hagen at PSU L. M. Z. Hagen (PSU) and J. R. Cummings (NASA/UMBC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 151205A 101 s after the BAT trigger (Cummings et al., GCN Circ. 18657). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 18658) 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 101 5796 383 >21.15 v 590 6207 236 >19.25 b 514 5591 236 >20.14 u 259 6713 552 >20.21 w1 639 6617 413 >20.10 m2 4776 6412 393 >20.07 w2 565 6002 236 >19.95 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).