{
  "bibcode": "2013GCN.14403....1P",
  "body": "K.L. Page (U. Leicester) and M. De Pasquale (UCL-MSSL) report on behalf\nof the Swift-XRT team:\n\nWe have analysed 2.7 ks of XRT data for GRB 130418A (De Pasquale  et\nal. GCN Circ. 14377),  from 119 s to 15.6 ks after the\tBAT trigger.\nThe data comprise 262 s in Windowed Timing (WT) mode (the first 9 s\nwere taken while Swift was slewing) with the remainder in Photon\nCounting (PC) mode. The enhanced XRT position for this burst was given\nby Evans et al. (GCN. Circ 14383).\n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=0.72 (+/-0.11), followed by a break at T+801 s to an\nalpha of 1.51 (+0.54, -0.30).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.24 (+/-0.06). The\nbest-fitting absorption column is  2.9 (+7.3, -2.9) x 10^20 cm^-2, at a\nredshift of 1.218, in addition to the Galactic value of 2.7 x 10^20\ncm^-2 (Kalberla et al. 2005). The PC mode spectrum has a photon index\nof 1.70 (+0.24, -0.23) and a best-fitting absorption column of 2.6\n(+3.0, -2.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10\nkeV flux conversion factor deduced from this spectrum  is 4.2 x 10^-11\n(4.8 x 10^-11) erg cm^-2 count^-1.\n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 2.7 x 10^20 cm^-2\nIntrinsic column:    2.6 (+3.0, -2.5) x 10^21 cm^-2 at z=1.218\nPhoton index:\t     1.70 (+0.24, -0.23)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00553847.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 14403,
  "createdOn": 1366434340000,
  "email": "klp5@leicester.ac.uk",
  "subject": "GRB 130418A: Swift-XRT refined Analysis",
  "submitter": "Kim Page at U.of Leicester  <klp5@leicester.ac.uk>",
  "eventId": "GRB 130418A"
}