{
  "bibcode": "2011GCN.12141....1S",
  "body": "G. Stratta (ASDC), V. D'Elia (ASDC) and S. T. Holland\n(CRESST/USRA/GSFC) report on behalf of the Swift-XRT team:\n\nWe have analysed 9.6 ks of XRT data for GRB 110709A (Holland  et al.\nGCN Circ. 12118), from 71 s to 19.3 ks after the  BAT trigger. The data\ncomprise 565 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Osborne et al. (GCN. Circ 12119).\n\nThe late-time light curve (from T0+5.2 ks) can be modelled with  a\npower-law decay with a decay index of alpha=1.72 (+/-0.10).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.21 (+0.09, -0.08). The\nbest-fitting absorption column is  7.5 (+0.6, -0.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.5 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 2.07 (+/-0.11) and a\nbest-fitting absorption column of 7.3 (+/-0.7) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 5.0 x 10^-11 (1.0 x 10^-10) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     7.3 (+/-0.7) x 10^21 cm^-2\nGalactic foreground: 1.5 x 10^20 cm^-2\nExcess significance: 17.8 sigma\nPhoton index:\t     2.07 (+/-0.11)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00456939.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 12141,
  "createdOn": 1310317885000,
  "email": "stratta@asdc.asi.it",
  "subject": "GRB 110709A: Swift-XRT refined Analysis",
  "submitter": "Giulia Stratta at ASDC  <stratta@asdc.asi.it>",
  "eventId": "GRB 110709A"
}