TITLE: GCN CIRCULAR NUMBER: 17296 SUBJECT: GRB 150110B: Swift/UVOT Upper Limits DATE: 15/01/11 06:47:06 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and P. A. Evans (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150110B 65 s after the BAT trigger (Evans et al., GCN Circ. 17291). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 17294) 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 65 215 147 >21.0 u_FC 277 527 246 >20.3 white 65 12665 1414 >21.7 v 607 6471 452 >19.6 b 532 11960 1140 >21.5 u 277 11047 1394 >21.1 w1 656 6881 452 >20.4 m2 631 6676 452 >20.5 w2 582 6267 452 >20.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.20 in the direction of the burst (Schlegel et al. 1998).