{
  "subject": "GRB 251103B: Swift/UVOT Upper Limits",
  "circularId": 42588,
  "eventId": "GRB 251103B",
  "body": "A.A. Breeveld (UCL-MSSL) and S. Lanava (PSU) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 251103B 140 s after the BAT trigger (Lanava et al., GCN Circ. 42556).\nNo optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 42558)is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nu_FC               140          390          246         >20.2\nwhite              420         1363          245         >21.1\nv                  470         1413          117         >19.0\nb                  395         1339           97         >19.8\nw1                 519         1462           97         >18.8\nm2                 494         1437          117         >18.8\nw2                 445         1389          117         >19.1\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.256 in the direction of the burst (Schlegel et al. 1998).\n",
  "submitter": "Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>",
  "createdOn": 1762351081896,
  "submittedHow": "email",
  "bibcode": "2025GCN.42588....1B"
}