{
  "bibcode": "2023GCN.33266....1L",
  "body": "S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 230204A\n156 s after the BAT trigger (D'Ai et al., GCN Circ. 33260).\nNo optical afterglow consistent with the XRT position\n(Evans et al. GCN Circ. 33261)\nis detected in the initial UVOT exposures.\nA known source with no significant signs of fading\nis detected 2.88 arcsec from the XRT position at:\n\nRA (J2000): 15h 52m 47.83s\nDec (J2000): -50d 54' 56.74\"\n\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(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           156            306          147          >17.5\nu_FC                  314            564          246         >19.1\nwhite                  156          1372          373         >17.8\nv                         645          1596          117         >15.9\nb                         570          1521            97         >17.9\nu                         314          5553          382         >19.1\nw1                      695           5489          274         >19.1\nm2                      670          1446            97         >18.8\nw2                       621          1571          117         >18.5\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 2.516 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 33266,
  "createdOn": 1675553786000,
  "email": "sjl5346@psu.edu",
  "subject": "GRB 230204A: Swift/UVOT Upper Limits",
  "submitter": "Sam LaPorte at PSU  <sjl5346@psu.edu>",
  "eventId": "GRB 230204A"
}