{
  "bibcode": "2017GCN.20962....1G",
  "body": "S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo\n(INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), A.\nCholden-Brown (PSU) and  report on behalf of the Swift-XRT team: report\non behalf of the Swift-XRT team:\n\nWe have analysed 7.4 ks of XRT data for GRB 170331A, from 127 s to 19.2\nks after the  BAT trigger. The data comprise 12 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=0.99 (+0.12, -0.10).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.5 (+/-0.3). The\nbest-fitting absorption column is  5.6 (+1.7, -1.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 4.7 x 10^20 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.3 x 10^-11 (7.8 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     5.6 (+1.7, -1.5) x 10^21 cm^-2\nGalactic foreground: 4.7 x 10^20 cm^-2\nExcess significance: 5.8 sigma\nPhoton index:\t     2.5 (+/-0.3)\n\nIf the light curve continues to decay with a power-law decay index of\n0.99, the count rate at T+24 hours will be 1.1 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.7 x\n10^-14 (8.9 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00744791.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20962,
  "createdOn": 1490980827000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 170331A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 170331A"
}