TITLE: GCN CIRCULAR NUMBER: 40981 SUBJECT: GRB 250704A: Swift/UVOT Detection DATE: 25/07/05 18:25:39 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18@psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250704A 2.9 ks after the SVOM/ECLAIRs trigger (Cao et al., GCN Circ. 40934). A source consistent with the XRT position (Osborne et al., GCN Circ. 40950) and the optical transient (Schneider et al., GCN Circ. 40953; Cao et al., GCN Circ. 40964) is detected in the UVOT exposures. The preliminary UVOT position is: RA (J2000) = 01:08:44.62 = 17.19427 (deg.) Dec (J2000) = -17:19:26.3 = -17.32398 (deg.) with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence). 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 u 2933 8704 1993 18.38+/-0.05 u 70704 76996 2879 20.77+/-0.28 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.015 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40981. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...