{
  "bibcode": "2009GCN..8946....1E",
  "body": "P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:\n\nSwift-XRT observed the field of GRB 090307 (BAT trigger 345551; GCN\nCircs. 8943, 8945) for 4.6 ks, from 135 s to 80 ks after the BAT\ntrigger. All of the data were taken in Photon Counting (PC) mode.  The\nX-ray source reported by Evans et al. (GCN Circ. 8943) is seen to fade,\nand is therefore identified as the afterglow, confirming the GRB nature\nof this BAT trigger. The source has an enhanced XRT position: RA, Dec =\n244.9944, -28.6333 which is equivalent to:\n\nRA (J2000): 16 19 58.64\nDec (J2000): -28 37 59.9\n\nwith an uncertainty of 2.1 arcsec (radius, 90% confidence). The light\ncurve shows a power-law decay, with an index 0.7 (+0.2, -0.1).\n\nThe PC mode spectrum can be fitted with an absorbed power-law, with a\nphoton index of 2.21 (+0.72, -0.60) and an absorbing column of 3.5\n(+2.7,-1.1) e21 cm-2, in excess of the Galactic value of 1.3e21 cm-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 4.1 x 10-11 (7.6 x 10-11) erg cm-2\ncount-1.\n\nIf the light curve continues to decay with alpha=0.7, the XRT count-rate\nat T+48 hrs will be 0.002 counts s-1, corresponding to an observed\n(unabsorbed) 0.3-10 keV flux of 7.38e-14 (1.4e-13) erg cm-2 s-1.\n\nThe results of the automatic XRT analysis are available online at\nhttp://www.swift.ac.uk/xrt_products/00345551.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 8946,
  "createdOn": 1236520498000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 090307: Swift-XRT afterglow confirmation and analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 090307"
}