{
  "submittedHow": "email",
  "subject": "GRB 250823A: Swift/UVOT Detection",
  "submitter": "Paul Kuin at MSSL <npkuin@gmail.com>",
  "createdOn": 1756028030620,
  "circularId": 41521,
  "body": "Paul Kuin (UCL/MSSL) and M. H. Siegel (PSU) report on behalf of the\nSwift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 250823A\n126 s after the BAT trigger (Siegel et al., GCN Circ. 41511). A source\nconsistent with the XRT position is detected in the initial UVOT exposures.\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric\nsystem (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early\nexposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite              126         1020          334         20.42 +/- 0.17\nv                  668         1244           78         18.43 +/- 0.28\nb                  594         1169           58         19.25 +/- 0.28\nu                  338         1317          304        >19.5\nw1                 718         1293           58        >19.1\nm2                 692         1268           58        >18.8\nw2                 644         1391           97        >19.3\n\nThe magnitudes in the table are not corrected for the Galactic extinction due\nto the reddening of E(B-V) = 0.111 in the direction of the burst (Schlegel\net al. 1998).\n",
  "eventId": "GRB 250823A",
  "bibcode": "2025GCN.41521....1K"
}