{
  "bibcode": "2017GCN.20965....1K",
  "body": "N. P. M. Kuin (UCL-MSSL) and A. Melandri (INAF-OAB)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field\nof GRB 170331A 128 s after the BAT trigger (Melandri et\nal., GCN Circ. 20946). No optical afterglow consistent\nwith the XRT position (Osborne et al. GCN Circ. 20960)\nis detected in the initial UVOT exposures. Preliminary\n3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for\nthe first finding chart (FC) exposure and subsequent\nexposures are:\n\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC           128          278          147         >20.4\nu_FC               286          536          246         >19.6\nwhite              128         1532          392         >21.0\nv                  616         1753          134         >18.5\nb                  542         1680          117         >19.1\nu                  286         1655          343         >19.7\nw1                 665         1631          117         >19.1\nm2                1069         1606           58         >19.4\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.05 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 20965,
  "createdOn": 1491003277000,
  "email": "npkuin@gmail.com",
  "subject": "GRB 170331A: Swift/UVOT Upper Limits",
  "submitter": "Paul Kuin at MSSL  <npkuin@gmail.com>",
  "eventId": "GRB 170331A"
}