TITLE: GCN CIRCULAR NUMBER: 9751 SUBJECT: GRB 090807: Swift/UVOT Upper Limits DATE: 09/08/07 23:57:25 GMT FROM: Craig Swenson at PSU/Swift C. A. Swenson (PSU) and Cannizzo (NASA/UMBC)report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 090807 164 s after the BAT trigger (Cannizzo et al., GCN Circ. 9746). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 9748) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 164 313 147 >21.2 u_FC 322 571 246 >20.1 white 164 1026 295 >21.1 u 322 571 246 >20.1 The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.18 in the direction of the burst (Schlegel et al. 1998).