{
  "bibcode": "2011GCN.12543....1Z",
  "body": "Bin-Bin Zhang (PSU) reports on behalf of the Swift-XRT team:\n\nWe have analysed 12 ks of XRT data for GRB 111107A (Siegel  et al. GCN\nCirc. 12534), from 55 s to 30.6 ks after the  BAT trigger. The data\ncomprise 42 s in Windowed Timing (WT) mode (the first 7 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 Osborne et\nal. (GCN. Circ 12538).\n\nThe late-time light curve (from T0+5.1 ks) can be modelled with  a\npower-law decay with a decay index of alpha=1.12 (+0.29, -0.27).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.15 (+0.12, -0.16). The\nbest-fitting absorption column is  3.5 (+6.0, -3.5) x 10^21 cm^-2, at a\nredshift of 2.893, in addition to the Galactic value of 8.9 x 10^20\ncm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed)\n0.3-10 keV flux conversion factor deduced from this spectrum  is 3.3 x\n10^-11 (4.5 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 8.9 x 10^20 cm^-2\nIntrinsic column:    3.5 (+6.0, -3.5) x 10^21 cm^-2 at z=2.893\nPhoton index:\t     2.15 (+0.12, -0.16)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00507185.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 12543,
  "createdOn": 1320687649000,
  "email": "bbzhang@psu.edu",
  "subject": "GRB 111107A: Swift-XRT refined Analysis",
  "submitter": "Binbin Zhang at PSU  <bbzhang@psu.edu>",
  "eventId": "GRB 111107A"
}