TITLE: GCN CIRCULAR NUMBER: 41291 SUBJECT: GRB 250807A: Swift/UVOT Detection DATE: 25/08/08 16:24:35 GMT FROM: s.shilling@lancaster.ac.uk S. P. R. Shilling (Lancaster U.) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250807A 111 s after the BAT trigger (Klingler et al., GCN Circ. 41262). A source consistent with the enhanced XRT position (Evans et al., GCN Circ. 41270) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 111 261 147 18.00 +/- 0.04 v 653 1769 136 >18.8 b 579 1695 117 >19.5 u 323 1840 361 19.88 +/- 0.31 w1 702 1818 117 >19.0 w2 801 821 19 >17.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.011 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/41291. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...