{
  "bibcode": "2015GCN.18617....1P",
  "body": "C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.\nLeicester), A. D'ai (INAF-IASFPA), A. Maselli  (INAF-IASFPA), A.\nMelandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),\nD.N. Burrows (PSU) and A. Amaral-Rogers report on behalf of the\nSwift-XRT team:\n\nWe have analysed 7.4 ks of XRT data for GRB 151118A (Amaral-Rogers et\nal. GCN Circ. 18611), from 52 s to 22.7 ks after the  BAT trigger. The\ndata comprise 22 s in Windowed Timing (WT) mode (the first 7 s were\ntaken while Swift was slewing) with the remainder in Photon Counting\n(PC) mode. The enhanced XRT position for this burst was given by Evans\net al. (GCN Circ. 18614).\n\nThe late-time light curve (from T0+4.9 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.07 (+/-0.26).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.93 (+0.23, -0.22). The\nbest-fitting absorption column is  1.07 (+0.25, -0.21) x 10^22 cm^-2,\nin excess of the Galactic value of 4.5 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 5.1 x 10^-11 (9.2 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.07 (+0.25, -0.21) x 10^22 cm^-2\nGalactic foreground: 4.5 x 10^21 cm^-2\nExcess significance: 4.7 sigma\nPhoton index:\t     1.93 (+0.23, -0.22)\n\nIf the light curve continues to decay with a power-law decay index of\n1.07, the count rate at T+24 hours will be 4.6 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.4 x\n10^-13 (4.2 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00664078.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 18617,
  "createdOn": 1447850691000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 151118A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 151118A"
}