{
  "eventId": "GRB 261017A",
  "circularId": 45979,
  "subject": "GRB 261017A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "body": "T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), J.J. DeLaunay (PSU), S.\nLanava (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page\n(U. Leicester), M.G. Bernardini (INAF-OAB) and P.A. Evans report on\nbehalf of the Swift-XRT team:\n\nWe have analysed 6.3 ks of XRT data for GRB 261017A, from 70 s to 43.9\nks after the   trigger. The data comprise 98 s in Windowed Timing (WT)\nmode (the first 9 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=1.7 (+0.5, -0.4). At T+100 s  the decay\nsteepens to an alpha of 5.0 (+0.7, -0.3) before breaking again at T+260\ns to a final decay with index alpha=1.12 (+0.30, -0.26).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.16 (+0.08, -0.07). The\nbest-fitting absorption column is  4.7 (+3.5, -1.5) x 10^20 cm^-2,\nconsistent with the Galactic value of 3.2 x 10^20 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 5.4 x 10^-11 (5.5 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     4.7 (+3.5, -1.5) x 10^20 cm^-2\nGalactic foreground: 3.2 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.16 (+0.08, -0.07)\n\nIf the light curve continues to decay with a power-law decay index of\n1.12, the count rate at T+24 hours will be 8.1 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.4 x\n10^-14 (4.5 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01519536.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "createdOn": 1792310231333,
  "submittedHow": "email"
}