{
  "bibcode": "2010GCN.10639....1R",
  "body": "A. Rowlinson (U Leicester) and W. H. Baumgartner (GSFC/UMBC) report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 6.9 ks of XRT data for GRB 100420A (Baumgartner et al.\nGCN Circ. 10628), from 115 s to 13.6 ks after the BAT trigger. The data\ncomprise 120 s in Windowed Timing (WT) mode (the first 8 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 Beardmore et\nal. (GCN. Circ 10638).\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=2.69 (+0.47, -0.39), followed by a break at T+721 s to an\nalpha of 1.22 (+0.34, -4.02).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.83 (+0.22, -0.20). The\nbest-fitting absorption column is consistent with the Galactic value of\n1.2 x 10^21 cm^-2 (Kalberla et al. 2005). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum is 4.2 x 10^-11 (5.3 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n1.22, the count rate at T+24 hours will be 2.3 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.7 x\n10^-15 (1.2 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/00419932.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10639,
  "createdOn": 1271803063000,
  "email": "bar7@star.le.ac.uk",
  "subject": "GRB 100420A: XRT refined analysis",
  "submitter": "Antonia Rowlinson at U.of Leicester  <bar7@star.le.ac.uk>",
  "eventId": "GRB 100420A"
}