TITLE: GCN CIRCULAR NUMBER: 19897 SUBJECT: GRB 160905A: Swift/UVOT Detection DATE: 16/09/06 10:55:43 GMT FROM: Sam Emery at MSSL-UCL S.W.K. Emery (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160905A 67 s after the BAT trigger (D'Avanzo et al., GCN Circ. 19887), which was also detected by Fermi-GBM (GCN 19889) and Fermi-LAT (GCN 19890). A fading source consistent with the XRT position (Osborne et al. GCN Circ. 19891) 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 67 216 147 15.8 ± 0.03 white 67 2234 469 17.1 ± 0.05 u_FC 280 530 246 18.3 ± 0.15 u 280 2185 401 18.8 ± 0.16 v 610 2285 195 17.4 ± 0.12 b 536 2210 175 18.7 ± 0.16 w1 660 2160 175 >19.1 m2 635 2296 162 >19.1 w2 586 2260 195 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.45 in the direction of the burst (Schlegel et al. 1998).