TITLE: GCN CIRCULAR NUMBER: 19970 SUBJECT: GRB 161001A: Swift/UVOT Upper Limits DATE: 16/10/01 11:40:49 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) 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 161001A 68 s after the BAT trigger (Page et al., GCN Circ. 19967). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 19969) 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 68 218 147 >20.8 u_FC 281 530 246 >20.2 white 68 1183 353 >20.4 v 611 1232 78 >19.1 b 536 1158 58 >19.1 u 281 5994 395 >20.2 w1 661 1282 78 >19.2 m2 636 1257 78 >19.2 w2 1016 1208 39 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).