TITLE: GCN CIRCULAR NUMBER: 20130 SUBJECT: GRB 161104A: Swift/UVOT Upper Limits DATE: 16/11/05 03:28:35 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and B. Mingo (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 161104A 69 s after the BAT trigger (Mingo et al., GCN Circ. 20123). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 20124) 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 69 170 99 >20.8 w1 4984 5184 197 >19.9 m2 4779 4979 197 >21.7 w2 5805 6005 197 >19.9 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).