TITLE: GCN CIRCULAR NUMBER: 41162 SUBJECT: GRB 250725A: Swift/UVOT Upper Limits DATE: 25/07/25 12:27:21 GMT FROM: s.shilling@lancaster.ac.uk S. P. R. Shilling (Lancaster U.) and P. A. Evans (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250725A 880 s after the BAT trigger (Evans et al., GCN Circ. 41152). No optical afterglow consistent with the enhanced XRT position (Osborne et al., GCN Circ. 41153) 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 880 1029 147 >21.0 white 880 2562 322 >21.2 v 1036 2439 175 >19.6 b 1134 2537 175 >20.1 u 1110 2340 156 >20.1 w1 1085 2488 175 >19.6 w2 1704 1898 39 >19.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.114 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/41162. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...