{
  "bibcode": "2012GCN.13330....1O",
  "body": "S. R. Oates (MSSL-UCL) and J. R. Cummings (NASA/UMBC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 120521B\n127 s after the BAT trigger (Cummings et al., GCN Circ. 13305).\nNo optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 13311)\nis 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           127          277          147         >19.4\nu_FC               286          535          246         >19.4\nwhite              127        30912         2930         >19.8\nv                  615        23584         2045         >18.7\nb                  541        36686         2819         >19.7\nu                  286        36128         2526         >20.2\nw1                 665        35215         2046         >20.7\nm2                5582        24489         1279         >21.0\nw2                 765        19363         1746         >21.1\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.45 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 13330,
  "createdOn": 1337684398000,
  "email": "sro@mssl.ucl.ac.uk",
  "subject": "GRB 120521B: Swift/UVOT Upper Limits",
  "submitter": "Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>",
  "eventId": "GRB 120521B"
}