TITLE: GCN CIRCULAR NUMBER: 17058 SUBJECT: GRB 141109B: Swift/UVOT Upper Limits DATE: 14/11/10 22:56:56 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 141109B 188 s after the BAT trigger (Melandri et al., GCN Circ. 17038). No optical afterglow consistent with the UVOT-enhanced XRT position (Beardmore et al., GCN Circ. 17045) 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 188 338 147 >20.1 u_FC 347 596 246 >20.4 white 188 6699 588 >21.3 v 677 7110 313 >20.4 b 602 6494 294 >21.0 u 347 13125 1061 >20.9 w1 727 12566 1207 >21.0 m2 701 7315 255 >20.8 w2 828 6905 255 >21.0 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).