{
  "bibcode": "2005GCN..4380....1W",
  "body": "J. Wren, W.T. Vestrand, R. White, P. Wozniak, and S. Evans report\non behalf of the RAPTOR team at Los Alamos National Laboratory:\n\nStarting at 02:57:05 UT (1.1 hours after the burst), the RAPTOR-S \ntelescope began a manually initiated response to the short burst \nidentified by Swift (Parsons et al. 4363).  Within the XRT error circle \n(Burrows et al. 4366) at a position consistent with the location of the \ncandidate J-band infrared (Bloom, GCN 4368) and R-band optical (Berger, \nGCN 4369) counterparts, a stack of 20 30-second unfiltered RAPTOR images \nyields a marginal detection of a source. Using the USNO-B1 catalog for \ncalibration and ignoring any extinction along the line of sight, our \nderived 5-sigma upper limit on the brightness of an optical counterpart \nat that epoch (1.3 hours after the trigger) is R=20.2+/-0.2 magnitude.",
  "circularId": 4380,
  "createdOn": 1135220062000,
  "email": "jwren@nis.lanl.gov",
  "subject": "GRB 051221A: RAPTOR Fading Counterpart Constraint",
  "submitter": "James Wren at LANL  <jwren@nis.lanl.gov>",
  "eventId": "GRB 051221A"
}