{
  "bibcode": "2016GCN.20212....1M",
  "body": "A. Melandri (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti\n(INAF-OAB/PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), S.L.\nGibson (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo\n(INAF-OAB), V. D'Elia (ASDC) and D. Kocevski report on behalf of the\nSwift-XRT team:\n\nWe have analysed 7.8 ks of XRT data for GRB 161129A (Kocevski et al.\nGCN Circ. 20210), from 90 s to 17.8 ks after the  BAT trigger. The data\nare entirely in Photon Counting (PC) mode. The enhanced XRT position\nfor this burst was given by Beardmore et al. (GCN Circ. 20211).\n\nThe late-time light curve (from T0+3.9 ks) can be modelled with a\npower-law decay with a decay index of alpha=2.21 (+0.15, -0.14).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.74 (+0.13, -0.12). The\nbest-fitting absorption column is  3.2 (+0.7, -0.6) x 10^21 cm^-2, in\nexcess of the Galactic value of 2.5 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 4.4 x 10^-11 (5.8 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     3.2 (+0.7, -0.6) x 10^21 cm^-2\nGalactic foreground: 2.5 x 10^21 cm^-2\nExcess significance: 2.0 sigma\nPhoton index:\t     1.74 (+0.13, -0.12)\n\nIf the light curve continues to decay with a power-law decay index of\n2.21, the count rate at T+24 hours will be 7.1 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.1 x\n10^-14 (4.1 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/00724438.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20212,
  "createdOn": 1480432512000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 161129A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 161129A"
}