{
  "createdOn": 1759907856891,
  "submittedHow": "email",
  "subject": "GRB 251007B: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "bibcode": "2025GCN.42160....1B",
  "body": "A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia\n(SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), J.A. Kennea (PSU), D.N.\nBurrows (PSU), S. Lanava (PSU), J.P. Osborne (U. Leicester) and P.A.\nEvans report on behalf of the Swift-XRT team:\n\nWe have analysed 6.4 ks of XRT data for GRB 251007B, from 134 s to 33.2\nks after the   trigger. The data comprise 6 s in Windowed Timing (WT)\nmode (taken while Swift was slewing), with the remainder in Photon\nCounting (PC) mode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.68 (+0.24, -0.26).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.79 (+0.39, -0.25). The\nbest-fitting absorption column is  6.5 (+3.1, -0.5) x 10^21 cm^-2,\nconsistent with the Galactic value of 6.0 x 10^21 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 5.0 x 10^-11 (7.5 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     6.5 (+3.1, -0.5) x 10^21 cm^-2\nGalactic foreground: 6.0 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.79 (+0.39, -0.25)\n\nIf the light curve continues to decay with a power-law decay index of\n1.68, the count rate at T+24 hours will be 3.9 x 10^-5 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x\n10^-15 (2.9 x 10^-15) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01402467.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "circularId": 42160,
  "eventId": "GRB 251007B"
}