TITLE: GCN CIRCULAR NUMBER: 16828 SUBJECT: GRB 140916A: Swift/UVOT Upper Limits DATE: 14/09/17 00:26:30 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and J. L. Racusin (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 140916A 160 s after the BAT trigger (Racusin et al., GCN Circ. 16819). No optical afterglow consistent with the XRT position (Evans GCN Circ. 16820) 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 160 310 147 >21.5 u_FC 318 568 246 >20.7 white 160 6731 608 >22.3 v 648 12894 1415 >21.2 b 574 19208 857 >20.8 u 318 24969 2113 >21.4 w1 697 30730 2826 >21.9 m2 844 30169 2742 >21.7 w2 796 29263 2203 >22.1 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).