{
  "bibcode": "2009GCN..9857....1R",
  "body": "A. Rowlinson (U. Leicester) and P. Schady (MSSL-UCL) report on behalf of\nthe Swift-XRT team:\n\nWe have analysed 8.4 ks of XRT data for GRB 090831C (Schady et al. GCN\nCirc. 9854), from 121 s to 21.8 ks after the BAT trigger. The data are\nentirely in Photon Counting (PC) mode. The enhanced XRT position for\nthis burst was given by Evans et al. (GCN. Circ 9855).\n\nThe light curve has two flares at T+186 s and T+440 s, while the\nunderlying decay can be modelled with a power-law decay with a decay\nindex of alpha=0.83 (+0.17, -0.11).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.84 (+0.21, -0.15). The\nbest-fitting absorption column is 3.254 (+1.001, -0.014) x 10^21 cm^-2,\nconsistent with the Galactic value of 3.2 x 10^21 cm^-2 (Kalberla et al.\n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum is 4.9 x 10^-11 (7.2 x 10^-11) erg\ncm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.83, the count rate at T+24 hours will be 0.0029 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x\n10^-13 (2.1 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/00361489.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9857,
  "createdOn": 1251788586000,
  "email": "bar7@star.le.ac.uk",
  "subject": "GRB 090831C: Swift XRT Refined Analysis",
  "submitter": "Antonia Rowlinson at U.of Leicester  <bar7@star.le.ac.uk>",
  "eventId": "GRB 090831C"
}