{
  "bibcode": "2017GCN.21114....1L",
  "body": "S. J. LaPorte (PSU), K.L. Page (U. Leicester), B. Mingo (U. Leicester),\nA.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri\n(INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti\n(INAF-OAB/PSU) and T.N. Ukwatta report on behalf of the Swift-XRT team:\n\nWe have analysed 9.5 ks of XRT data for GRB 170519A (Ukwatta et al. GCN\nCirc. 21106), from 73 s to 23.1 ks after the  BAT trigger. The data\ncomprise 291 s in Windowed Timing (WT) mode (the first 6 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. 21107).\n\nThe late-time light curve (from T0+4.1 ks) can be modelled with a\npower-law decay with a decay index of alpha=0.94 (+/-0.08).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.62 (+/-0.05). The\nbest-fitting absorption column is  1.78 (+0.12, -0.11) x 10^21 cm^-2,\nin excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.98 (+/-0.10) and a\nbest-fitting absorption column of 1.20 (+0.29, -0.27) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.4 x 10^-11 (4.3 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.20 (+0.29, -0.27) x 10^21 cm^-2\nGalactic foreground: 2.4 x 10^20 cm^-2\nExcess significance: 5.8 sigma\nPhoton index:\t     1.98 (+/-0.10)\n\nIf the light curve continues to decay with a power-law decay index of\n0.94, the count rate at T+24 hours will be 0.030 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x\n10^-12 (1.3 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00753445.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 21114,
  "createdOn": 1495210848000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 170519A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 170519A"
}