{
  "bibcode": "2017GCN.20852....1D",
  "body": "A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), A. Cholden-Brown (PSU), S.\nJ. LaPorte (PSU), K.L. Page (U. Leicester), B. Mingo (U. Leicester),\nA.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo\n(INAF-OAB) and\treport on behalf of the Swift-XRT team: report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 6.8 ks of XRT data for GRB 170311A, from 108 s to 35.6\nks after the  BAT trigger. The data comprise 64 s in Windowed Timing\n(WT) mode with the remainder in Photon Counting (PC) mode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.59 (+0.16, -0.17).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.52 (+0.28, -0.26). The\nbest-fitting absorption column is  2.2 (+1.5, -0.9) x 10^21 cm^-2,\nconsistent with the Galactic value of 1.3 x 10^21 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.8 x 10^-11 (5.6 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.2 (+1.5, -0.9) x 10^21 cm^-2\nGalactic foreground: 1.3 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.52 (+0.28, -0.26)\n\nIf the light curve continues to decay with a power-law decay index of\n1.59, the count rate at T+24 hours will be 6.1 x 10^-5 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.9 x\n10^-15 (3.4 x 10^-15) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00741965.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20852,
  "createdOn": 1489289378000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 170311A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 170311A"
}