{
  "bibcode": "2014GCN.16187....1M",
  "body": "F. E. Marshall (NASA/GSFC) and D. Kocevski (NASA/GSFC/ORAU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 140428A\n104 s after the BAT trigger (Kocevski et al., GCN Circ. 16177).\nNo optical afterglow consistent with the optical position\n(Perley, GCN_Circ. 16180) 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 initial exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite              104          254          147         >21.2\nv                 5454         5653          197         >20.3\nb                 4838         5039          197         >21.4\nu                  264          271            7         >19.5\nuw1               5864         6030          197         >20.5\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.009 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 16187,
  "createdOn": 1398805987000,
  "email": "femarsha@khamseen.gsfc.nasa.gov",
  "subject": "GRB 140428A: Swift/UVOT Upper Limits",
  "submitter": "Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>",
  "eventId": "GRB 140428A"
}