{
  "circularId": 42442,
  "eventId": "GRB 251024A",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "createdOn": 1761415755690,
  "subject": "GRB 251024A: Swift-XRT refined Analysis",
  "submittedHow": "email",
  "bibcode": "2025GCN.42442....1D",
  "body": "S. Dichiara (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.\nLeicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), C.\nSalvaggio (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A.\nEvans report on behalf of the Swift-XRT team:\n\nWe have analysed 4.4 ks of XRT data for GRB 251024A, from 113 s to 56.4\nks after the   trigger. The data comprise 30 s in Windowed Timing (WT)\nmode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode.  The late-time light curve\n(from T0+4.5 ks) is consistent with a constant source of mean count\nrate 4.5e-01 ct/sec. A power-law fit gives an index of -0.14 (+0.15,\n-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 2.06 (+0.16, -0.11). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 3.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.2 x 10^-11 (3.6 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     3.7 (+/-2.8) x 10^20 cm^-2\nGalactic foreground: 3.7 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     2.06 (+0.16, -0.11)\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01406589.\n\nThis circular is an official product of the Swift-XRT team.\n"
}