{
  "bibcode": "2016GCN.20198....1D",
  "body": "V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), T.G.R.\nRoegiers (PSU), L.M. McCauley (PSU), J.A. Kennea (PSU), B. Mingo (U.\nLeicester), A.P. Beardmore (U. Leicester) and E. Troja (NASA/GSFC/UMCP)\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 5.9 ks of XRT data for GRB 161117B (Troja et al. GCN\nCirc. 20182), from 65 s to 206.7 ks after the  BAT trigger. The data\ncomprise 178 s in Windowed Timing (WT) mode (the first 7 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 Osborne et\nal. (GCN Circ. 20186).\n\nThe light curve shows an initial bright flare that is part of \nthe prompt GRB emission. At T+95.1 s the decay can be modelled with \na power-law of index alpha of 0.43 (+0.09, -0.07) before breaking at\nT+101 ks to a final decay with index alpha=6.7 (+1.3, -5.2).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.10 (+/-0.05). The\nbest-fitting absorption column is  3.8 (+/-0.4) x 10^21 cm^-2, in\nexcess of the Galactic value of 6.5 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.98 (+0.24, -0.23)\nand a best-fitting absorption column of 5.3 (+1.5, -1.3) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 4.2 x 10^-11 (6.8 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     5.3 (+1.5, -1.3) x 10^21 cm^-2\nGalactic foreground: 6.5 x 10^20 cm^-2\nExcess significance: 5.9 sigma\nPhoton index:\t     1.98 (+0.24, -0.23)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00722642.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 20198,
  "createdOn": 1479647802000,
  "email": "antonino.dai@ifc.inaf.it",
  "subject": "GRB 161117B: Swift-XRT refined Analysis",
  "submitter": "Antonino D'Ai at IASF-PA  <antonino.dai@ifc.inaf.it>",
  "eventId": "GRB 161117B"
}