{
  "bibcode": "2023GCN.33292....1S",
  "body": "M. H. Siegel (PSU) and V. D���Elia (SSDC & INAF-OAR)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 230204B\n80 ks after the MAXI trigger (Serino et al., GCN Circ. 33265).\nNo optical afterglow consistent with the optical or XRT positions\n(Swain et al., GCN Circ. 33269, Smartt et al., GCN Circ. 33278, D���Elia et al.,\nGCN Circ. 33285) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nv                81062       109630          314         >19.1\nb                80652       109220          314         >20.1\nu                80567       109136          314         >19.8\nw1               80403       109052          629         >20.1\nm2               81146       109877         2154         >20.9\nw2               80737       109546         1259         >20.7\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.109 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 33292,
  "createdOn": 1675716639000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 230204B: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 230204B"
}