{
  "subject": "GRB 251202A: Swift/UVOT Detection",
  "submitter": "Paul Kuin at MSSL <npkuin@gmail.com>",
  "bibcode": "2025GCN.42956....1K",
  "createdOn": 1764693343715,
  "eventId": "GRB 251202A",
  "circularId": 42956,
  "submittedHow": "email",
  "body": "N.P.M. Kuin (UCL-MSSL) and M. J. Moss (GSFC) report on behalf of the\nSwift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of EP251202a/GRB\n251202A  17,500s after the EP trigger (Zhang et al., GCN Circ. No 42937).\n\nA source consistent with Li et al. (GCN Circ No 42934) and the XRT\nposition (Sbarufatti\net al. GCN Circ. No. 42943) is detected in the initial UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) = 08:08:27.5 = 122.11420 (deg.)\n    Dec (J2000) = 40:36:45.3 = 40.61244 (deg.)\nwith an estimated uncertainty of 0.48 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric\nsystem\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures\nare:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nu                17500         18104         509          19.80 +/- 0.20\nu                23697         24044         342         20.26 +/- 0.39\nu                28710         28841         129         20.06 +/- 0.53\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.043 in the direction of the burst\n(Schlegel et al. 1998).\n"
}