TITLE: GCN CIRCULAR NUMBER: 20157 SUBJECT: GRB 161105A: Swift/UVOT Upper Limits DATE: 16/11/09 17:08:21 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 161105A 586 s after the BAT trigger (Page et al., GCN Circ. 20131). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 20135) 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 exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white (fc) 586 735 147 >20.44 white 586 5286 549 >21.11 v 1046 7179 274 >18.86 b 841 5081 274 >20.07 u 816 1652 86 >18.62 uvw1 792 11242 713 >19.91 uvm2 767 7384 293 >19.12 uvw2 1022 6974 290 >19.24 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.33 in the direction of the burst (Schlegel et al. 1998).