{
  "bibcode": "2009GCN..9298....1R",
  "body": "A. Rowlinson (U. Leicester) and T. N. Ukwatta (GSFC/GWU) report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 8.9 ks of XRT data for GRB 090429B (Ukwatta et al. GCN\nCirc. 9281), from 104 s to 29.9 ks after the BAT trigger. The data are\nentirely in Photon Counting (PC) mode. The enhanced XRT position for\nthis burst was given by Beardmore et al. (GCN. Circ 9288).\n\nThe light curve initially shows a slow rise, which can be fitted with a\npower-law of index 0.89 (+0.36, -0.46). At around T+642 s the light\ncurve breaks to a power-law decay, with index 1.20 (+0.11, -0.10).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.00 (+0.15, -0.24). The\nbest-fitting absorption column is 10.0 (+4.2, -5.3) x 10^20, in excess\nof the Galactic value of 1.2 x 10^20 cm^-2 (Kalberla et al. 2005). The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 3.8 x 10^-11 (4.9 x 10^-11) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n1.20, the count rate at T+24 hours will be 0.0014 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x\n10^-14 (6.9 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00350854.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9298,
  "createdOn": 1241036052000,
  "email": "bar7@star.le.ac.uk",
  "subject": "GRB 090429B: Swift XRT refined analysis",
  "submitter": "Antonia Rowlinson at U.of Leicester  <bar7@star.le.ac.uk>",
  "eventId": "GRB 090429B"
}