{
  "eventId": "GRB 250704A",
  "bibcode": "2025GCN.40981....1S",
  "submitter": "Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>",
  "createdOn": 1751739939004,
  "circularId": 40981,
  "format": "text/plain",
  "body": "M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:\n\nThe 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.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  01:08:44.62 =  17.19427 (deg.)\n    Dec (J2000) = -17:19:26.3  = -17.32398 (deg.)\nwith an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: \n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nu                 2933         8704         1993      18.38+/-0.05\nu                70704        76996         2879      20.77+/-0.28\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.015 in the direction of the burst\n(Schlegel et al. 1998).",
  "submittedHow": "web",
  "subject": "GRB 250704A: Swift/UVOT Detection"
}