TITLE: GCN CIRCULAR NUMBER: 13616 SUBJECT: GRB 120807A: Swift/UVOT Upper Limits DATE: 12/08/10 14:32:49 GMT FROM: Mike Siegel at PSU/Swift MOC GRB 120807A: Swift/UVOT Upper Limits M. H. Siegel (PSU) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 120807A 75 s after the BAT trigger (Marshall et al., GCN Circ. 13602). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 13603) 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 75 225 147 >20.6 u_FC 288 537 246 >20.4 white 75 1884 431 >21.8 v 618 1935 156 >19.6 b 543 1860 136 >20.4 u 288 1835 363 >20.7 w1 668 1810 136 >20.3 m2 1591 1611 19 >18.8 w2 593 1910 117 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.41 in the direction of the burst (Schlegel et al. 1998).