{
  "bibcode": "2009GCN..8970....1E",
  "body": "P. A. Evans (U Leicester) reports on behalf of the Swift-XRT team:\n\nWe have analysed 5.5 ks of XRT data for GRB 090309 (Evans et al. GCN \nCirc. 8964), from 86 s to 12.4 ks after the BAT trigger. The data are \nentirely in Photon Counting (PC) mode. The enhanced XRT position for \nthis burst was given by Goad et al. (GCN. Circ 8969).\n\nThe light curve can be modelled with a power-law decay with a decay \nindex of alpha=0.38 (+0.08, -0.09).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed \npower-law with a photon spectral index of 2.2 (+/-0.3). The best-fitting \nabsorption column is 2.8 (+1.5, -1.1) x 10^21, in excess of the Galactic \nvalue of 1.1 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to \nobserved (unabsorbed) 0.3-10 keV flux conversion factor deduced from \nthis spectrum is 4.0 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of \n0.38, the count rate at T+24 hours will be 0.012 count s^-1, \ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.8 x \n10^-13 (8.2 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at \nhttp://www.swift.ac.uk/xrt_products/00345945.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 8970,
  "createdOn": 1236699836000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 090309: Swift-XRT refined analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 090309"
}