{
  "submittedHow": "email",
  "body": "V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C. Salvaggio\n(INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara (PSU),\nJ.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 6.5 ks of XRT data for GRB 251007A, from 58 s to 39.2\nks after the   trigger. The data comprise 362 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 late-time light curve (from T0+11.9 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.46 (+/-0.13).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.92 (+/-0.04). The\nbest-fitting absorption column is  1.79 (+0.15, -0.14) x 10^21 cm^-2,\nin excess of the Galactic value of 4.0 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.82 (+/-0.12) and a\nbest-fitting absorption column of 1.6 (+/-0.4) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.9 x 10^-11 (4.9 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.6 (+/-0.4) x 10^21 cm^-2\nGalactic foreground: 4.0 x 10^20 cm^-2\nExcess significance: 5.1 sigma\nPhoton index:\t     1.82 (+/-0.12)\n\nIf the light curve continues to decay with a power-law decay index of\n1.46, the count rate at T+24 hours will be 0.052 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x\n10^-12 (2.5 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01402466.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "createdOn": 1759912451639,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "bibcode": "2025GCN.42162....1D",
  "subject": "GRB 251007A: Swift-XRT refined Analysis",
  "circularId": 42162,
  "eventId": "GRB 251007A"
}