{
  "bibcode": "2011GCN.12298....1I",
  "body": "S. Immler (NASA/CRESST/GSFC) and E. Troja (NASA/GSFC/ORAU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 110820A\n139 s after the BAT trigger (Troja et al., GCN Circ. 12288).\nNo optical afterglow consistent with the enhanced XRT position\n(Beardmore et al., GCN Circ. 12291) and the position of the\noptical afterglow candidate Myungshin et al., GCN Circ. 12297)\nis detected in the initial UVOT exposures.\n\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)\nexposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nu_FC               139          389          246 >20.6\nv                  445        24186         1395 >21.1\nb                  394        12987          932 >22.0\nu                  139        18761         2181 >21.8\nw1                 494        18331         2155 >21.8\nm2                 469        24536         1716 >20.6\nw2                 420        23272         1396 >21.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.55 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 12298,
  "createdOn": 1314022806000,
  "email": "stefan.m.immler@nasa.gov",
  "subject": "GRB 110820A: Swift/UVOT Upper Limits",
  "submitter": "Stefan Immler at NASA/GSFC  <stefan.m.immler@nasa.gov>",
  "eventId": "GRB 110820A"
}