{
  "subject": "GRB 251007B: Swift/UVOT Upper Limits",
  "circularId": 42193,
  "eventId": "GRB 251007B",
  "body": "GRB 251007B: Swift/UVOT Upper Limits\n\nM. H. Siegel (PSU) and A. Melandri (INAF-OAR) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 251007B 152 s after the BAT trigger (Melandri et al., GCN Circ. 42147). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ 42159) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC           152          302          147         >19.8\nu_FC               311          561          246         >19.1\nwhite              152         5220          220         >19.9\nv                  641         4360          220         >19.2\nb                  567         5181          236         >20.3\nu                  311         4975          462         >19.5\nw1                 691         4770          216         >19.8\nm2                 665         4565          216         >19.5\nw2                 616          810           39         >18.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.786 in the direction of the burst\n(Schlegel et al. 1998).\n",
  "bibcode": "2025GCN.42193....1S",
  "format": "text/plain",
  "submittedHow": "web",
  "createdOn": 1760119223623,
  "submitter": "Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>"
}