TITLE: GCN CIRCULAR NUMBER: 19267 SUBJECT: GRB 160408A: Swift/UVOT Upper Limits DATE: 16/04/08 20:15:45 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and P. A. Evans (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160408A 98 s after the BAT trigger (Evans et al., GCN Circ. 19260). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 19261) or the possible optical counterparts (Levan et al., GCN Circ. 19262) 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 98 248 147 >21.0 u_FC 311 561 246 >19.7 white 98 1365 373 >21.8 v 641 1414 97 >19.4 b 566 1340 78 >19.6 u 311 1316 304 >19.9 w1 691 1291 58 >19.5 m2 838 1092 39 >18.8 w2 617 1390 97 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the burst (Schlegel et al. 1998).