{
  "bibcode": "2010GCN.11022....1P",
  "body": "C. Pagani (U. Leicester) and D. C. Morris (GWU/GSFC) report on behalf of\nthe Swift-XRT team:\n\nWe have analysed 6.8 ks of XRT data for GRB 100728B (Morris et al. GCN\nCirc. 11009), from 81 s to 17.4 ks after the BAT trigger. The data\ncomprise 86 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 Evans et al.\n(GCN. Circ 11017).\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.109 (+0.029, -0.030).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.20 (+/-0.20). The\nbest-fitting absorption column is 1.2 (+0.4, -0.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 6.2 x 10^20 cm^-2 (Kalberla et al.\n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum is 3.5 x 10^-11 (5.0 x 10^-11) erg\ncm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n1.109, the count rate at T+24 hours will be 5.0 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x\n10^-13 (2.5 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/00430172.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 11022,
  "createdOn": 1280348798000,
  "email": "cp232@star.le.ac.uk",
  "subject": "GRB 100728B: Swift-XRT Refined Analysis",
  "submitter": "Claudio Pagani at U of Leicester  <cp232@star.le.ac.uk>",
  "eventId": "GRB 100728B"
}