{
  "bibcode": "2012GCN.13037....1O",
  "body": "S. R. Oates (MSSL-UCL) and C. B. Markwardt (NASA/GSFC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 120311A\n3164 s after the BAT trigger (Markwardt et al., GCN Circ. 13032).\nNo optical afterglow, consistent with the refined XRT position\n(Goad et al .,GCN Circ 13035) or optical position reported by the\nLiverpool Telescope (Melandri et al., GCN Circ 13033), is detected within\nthe initial UVOT exposures. Preliminary 3-sigma upper limits using\nthe UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)\nfor the first finding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC          3164         3314          147         >16.4\nwhite             3164        16486         2114         >16.5\nv                 3321        20754         1454         >15.8\nb                 4141        15574         1224         >16.4\nu                 3936         5571          393         >16.3\nw1                3731         5366          393         >17.7\nm2                3526         5161          393         >19.0\nw2                4552        17272         1850         >19.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.13 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 13037,
  "createdOn": 1331478985000,
  "email": "msslba@googlemail.com",
  "subject": "GRB 120311A: Swift/UVOT Upper Limits",
  "submitter": "Patricia Schady at MPE/Swift  <msslba@googlemail.com>",
  "eventId": "GRB 120311A"
}