TITLE: GCN CIRCULAR NUMBER: 41265 SUBJECT: GRB 250805A: Swift/UVOT Upper Limits DATE: 25/08/07 12:47:42 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18@psu.edu> M. H. Siegel (PSU) and Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250805A 3536 s after the BAT trigger (Ambrosi et al., GCN Circ. 41233). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 41238) or optical afterglow (Izzo et al., GCN Circ. 41241; Li et al., GCN Circ. 41241) 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 3536 3686 147 >21.3 white 3536 4306 344 >21.7 b 3902 4101 197 >20.9 u 3696 3895 197 >20.6 w2 4312 4460 146 >20.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.092 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/41265. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...