{
  "bibcode": "2019GCN.25851....1S",
  "body": "B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P.\nOsborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U.\nLeicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB) and A.\nMelandri report on behalf of the Swift-XRT team:\n\nWe have analysed 10 ks of XRT data for GRB 190926A (Melandri et al. GCN\nCirc. 25848), from 140 s to 23.8 ks after the  BAT trigger. The data\ncomprise 685 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Goad et al. (GCN Circ. 25850).\n\nThe late-time light curve (from T0+4.1 ks) can be modelled with an\ninitial power-law decay with an index of alpha=0.661 (+0.053, -0.030),\nfollowed by a break at T+677 s to an alpha of 3.34 (+0.30, -0.12).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.804 (+/-0.023). The\nbest-fitting absorption column is  3.00 (+/-0.11) x 10^21 cm^-2, in\nexcess of the Galactic value of 7.5 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 4.1 x 10^-11 (5.5 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     3.00 (+/-0.11) x 10^21 cm^-2\nGalactic foreground: 7.5 x 10^20 cm^-2\nExcess significance: 33.3 sigma\nPhoton index:\t     1.804 (+/-0.023)\n\nIf the light curve continues to decay with a power-law decay index of\n3.34, the count rate at T+24 hours will be 3.2 x 10^-6 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x\n10^-16 (1.7 x 10^-16) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00926515.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 25851,
  "createdOn": 1569527130000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 190926A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 190926A"
}