{
  "subject": "GRB 251203C: Swift/UVOT Upper Limit",
  "eventId": "GRB 251203C",
  "submittedHow": "web",
  "bibcode": "2025GCN.43014....1K",
  "createdOn": 1765045362286,
  "circularId": 43014,
  "submitter": "N. Klingler at NASA-GSFC/UMBC/CRESST II <noelklingler@gmail.com>",
  "format": "text/plain",
  "body": "Swift/UVOT has performed follow-up observations of the field of GRB 251203C, starting 20.3 ks after the SVOM trigger sb25120305 (Brunet et al; GCN Circ. 42976).  No source is detected at the position of the optical counterpart (R.A., Dec. = 51.701538, -7.382688) reported by Li et al. (GCN Circ. 42987) and Turpin et al. (GCN Circ. 42988).  3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are:\n\nFilter\t\tT_start(s)\tT_stop(s)\tExp(s)\t\tMag(AB)\nu\t\t20269\t\t20514\t\t241\t\t>20.69\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.046 in the direction of the burst (Schlegel et al. 1998)."
}