TITLE: GCN CIRCULAR NUMBER: 14314 SUBJECT: GRB 130313A: Swift/UVOT Upper Limits DATE: 13/03/15 21:41:57 GMT FROM: Tyler Pritchard at PSU T. A. Pritchard (PSU) and B. P. Gompertz (U Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 130313A 81 s after the BAT trigger (Gompertz et al., GCN Circ. 14293). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 14300) 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 81 231 147 >20.6 u_FC 293 543 246 >20.3 white 81 17899 2332 >22.4 v 625 22348 1681 >20.4 b 550 16987 1327 >21.4 u 293 6955 697 >20.3 w1 674 6750 471 >20.9 m2 649 6545 413 >21.0 w2 600 18671 2110 >21.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.09 in the direction of the burst (Schlegel et al. 1998).