{
  "bibcode": "2009GCN..9825....1E",
  "body": "P.A. Evans (U. Leicester), C. Guidorzi (U Ferrara) and W.H. Baumgartner\n(GSFC/UMBC) report on behalf of the Swift-XRT team:\n\nSwift conducted a second observation of GRB 090817 (Beckmann et al. GCN\nCirc. 9815), collecting 3.9 ks of Photon Counting (PC) mode XRT data in\nthe interval T0+50 ks to T0+58 ks. The source reported by Evans et al.\n(GCN Circ. 9819) has faded to a level of ~0.015 ct s^-1. A power-law fit\nto the light curve yields a temporal decay index of alpha=0.9+/-0.2\n\nInspecting the USNO-B1 catalogue within 3.5' of the GRB we find 216\nobjects with R2<20.0. The probability of finding a USNO-B1 source within\na 2\" radius circle in this field is thus 2%. The strength of the\npotential association between the XRT and USNO-B1 sources noted in GCN\nCirc. 9819 is therefore fairly weak.\n\nWe therefore suggest that the XRT source is the afterglow of GRB 090817.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00020108.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9825,
  "createdOn": 1250585521000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 090817: Confirmation of the X-ray afterglow",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 090817"
}