{
  "bibcode": "2012GCN.13312....1O",
  "body": "S. R. Oates (MSSL-UCL) and M. M. Chester (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 120521A\n77 s after the BAT trigger (Chester et al., GCN Circ. 13302).\nNo optical afterglow consistent with the XRT position\n(Goad et al., GCN Circ. 13304) 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 first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC            77          227          147         >21.4\nu_FC               289          539          246         >20.9\nwhite               77         5491          363         >21.9\nv                 4266         5901          393         >19.7\nb                  545        11343          766         >21.9\nu                  289        10775         1386         >21.6\nw1                4676         6312          393         >20.4\nm2                4470         6106          393         >20.6\nw2                4061         5697          393         >20.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.43 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 13312,
  "createdOn": 1337609101000,
  "email": "sro@mssl.ucl.ac.uk",
  "subject": "GRB 120521A: Swift/UVOT Upper Limits",
  "submitter": "Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>",
  "eventId": "GRB 120521A"
}