TITLE: GCN CIRCULAR NUMBER: 19123 SUBJECT: GRB 160228A: Swift/UVOT Upper Limits DATE: 16/02/29 22:50:24 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and D. Malesani (DARK/NBI) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160228A 83 s after the BAT trigger (Malesani et al., GCN Circ. 19107). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 19110) or the position of the GROND optical afterglow candidate (Delvaux et al. GCN Circ. 19114) 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) exposures and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 83 233 147 >20.2 u_FC 296 546 246 >19.5 white 83 10111 342 >20.5 v 625 5975 236 >19.0 b 551 6695 138 >19.8 u 296 6589 462 >20.2 w1 675 6385 235 >19.8 m2 650 6179 236 >19.9 w2 601 5770 235 >19.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998).