{
  "bibcode": "2010GCN.10518....1L",
  "body": "O. M. Littlejohns, P. A. Evans, K. L. Page (U. Leicester) and W. H.\nBaumgartner (GSFC/UMBC) report on behalf of the Swift-XRT team:\n\nWe have analysed 2.9 ks of XRT data for GRB 100316B (Baumgartner et al.\nGCN Circ. 10489), from 75 s to 40.1 ks after the BAT trigger. The data\nare entirely in Photon Counting (PC) mode. The enhanced XRT position for\nthis burst was given by Beardmore et al. (GCN. Circ 10502).\n\nThe light curve can be modelled with a broken power-law decay with an\ninitial decay index of alpha=0.1 (+/-0.2), followed by a break at T~1100\ns to a final decay of alpha=1.2 (+0.5, -0.1).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.35 (+0.24, -0.21). The\nbest-fitting absorption column is 4.1 (+2.7, -1.3) x 10^21 cm^-2, at a\nredshift of 1.18 (Vergani et al. GCN Circ 10495), in addition to the\nGalactic value of 9.9 x 10^20 cm^-2 (Kalberla et al. 2005). The counts\nto observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from\nthis spectrum is 3.4 x 10^-11 (5.8 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n1.2, the count rate at T+48 hours will be 6.6 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x\n10^-14 (3.8 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/00416103.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10518,
  "createdOn": 1268818212000,
  "email": "oml2@star.le.ac.uk",
  "subject": "GRB 100316B: Swift-XRT refined analysis",
  "submitter": "Owen Littlejohns at U of Leicester  <oml2@star.le.ac.uk>",
  "eventId": "GRB 100316B"
}