{
  "bibcode": "2010GCN.10586....1E",
  "body": "P.A. Evans (U. Leicester) and S. T. Holland (CRESST/USRA/GSFC) report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 5.3 ks of XRT data for GRB 100413A (Holland et al. GCN\nCirc. 10581), from 129 s to 30.4 ks after the BAT trigger. The data\ncomprise 551 s in Windowed Timing (WT) mode (the first 9 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Goad et al.\n(GCN. Circ 10584).\n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=2.53 (+/- 0.07). At T+430 s the decay\nflattens to an alpha of 1.20 (+/- 0.04). The light curve breaks again\nat T+9980 s to a poorly-constrained final decay with alpha=2.3 (-0.5,\npositive error is unconstrained).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.83 (+/-0.06). The\nbest-fitting absorption column is 2.42 (+0.19, -0.18) x 10^21 cm^-2, in\nexcess of the Galactic value of 7.3 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 2.06 (+0.13, -0.12)\nand a best-fitting absorption column of 3.1 (+/-0.4) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 4.5 x 10^-11 (7.4 x 10^-11) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n2.3, the count rate at T+24 hours will be 2.02 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.1 x\n10^-14 (1.5 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/00419404.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10586,
  "createdOn": 1271232991000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 100413A: Swift-XRT Refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 100413A"
}