{
  "createdOn": 1749656368375,
  "subject": "GRB 250610B: Swift/UVOT Detection",
  "eventId": "GRB 250610B",
  "body": "A.A. Breeveld (UCL-MSSL) and M.A. Williams (PSU) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 250610B\n2 ks after the SVOM trigger (Saccardi et al., GCN Circ. 40671).\nThe optical source at the position of XRT source 1 (Evans et al., GCN Circ. 40679) seen by Schneider et al., (GCN Circ. 40676), Gompertz et al., (GCN Circ. 40677), Li et al., (GCN Circ. 40678), Bochenek et al., (GCN Circ. 40684) and Qiu et al. (GCN Circ. 40685) was also detected in the UVOT U-band filter and shows signs of fading.\n\nPreliminary 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:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nu                 2939         4660         1694         20.20 ± 0.15\nu                 8634         8923          285         20.50 ± 0.36\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.0104 in the direction of the burst (Schlegel et al. 1998).\n",
  "submittedHow": "email",
  "bibcode": "2025GCN.40691....1B",
  "circularId": 40691,
  "submitter": "Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>"
}