TITLE: GCN CIRCULAR NUMBER: 20029 SUBJECT: GRB 161011A: Swift/UVOT Upper Limits DATE: 16/10/11 17:23:48 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 161011A 118 s after the BAT trigger (D'Elia et al., GCN Circ. 20023). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 20026) 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 118 268 147 >20.7 u_FC 330 580 246 >20.0 white 118 1009 334 >21.1 v 660 6564 255 >19.4 b 586 11301 252 >20.3 u 330 11089 1170 >20.6 w1 709 6889 152 >20.4 m2 6569 6769 197 >20.3 w2 1015 6359 216 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998).