{
  "bibcode": "2016GCN.20298....1M",
  "body": "B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.\nLeicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia\n(ASDC), L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti\n(INAF-OAB/PSU) and A. D'Ai report on behalf of the Swift-XRT team:\n\nWe have analysed 7.7 ks of XRT data for GRB 161219B (D'Ai et al. GCN\nCirc. 20296), from 92 s to 22.7 ks after the  BAT trigger. The data\ncomprise 238 s in Windowed Timing (WT) mode (the first 9 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Beardmore\net al. (GCN Circ. 20297).\n\nThe late-time light curve (from T0+4.7 ks) can be modelled with a\npower-law decay with a decay index of alpha=0.75 (+/-0.07).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.05 (+/-0.08). The\nbest-fitting absorption column is  1.21 (+0.21, -0.20) x 10^21 cm^-2,\nin excess of the Galactic value of 3.1 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.82 (+/-0.07) and a\nbest-fitting absorption column of 1.64 (+0.23, -0.22) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.9 x 10^-11 (4.8 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.64 (+0.23, -0.22) x 10^21 cm^-2\nGalactic foreground: 3.1 x 10^20 cm^-2\nExcess significance: 9.8 sigma\nPhoton index:\t     1.82 (+/-0.07)\n\nIf the light curve continues to decay with a power-law decay index of\n0.75, the count rate at T+24 hours will be 0.22 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.3 x\n10^-12 (1.0 x 10^-11) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00727541.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20298,
  "createdOn": 1482208561000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 161219B: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 161219B"
}