{
  "subject": "GRB 251005C: Swift-XRT refined Analysis",
  "submittedHow": "email",
  "bibcode": "2025GCN.42119....1O",
  "createdOn": 1759725536300,
  "circularId": 42119,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 251005C",
  "body": "J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore\n(U. Leicester), E. Ambrosi  (INAF-IASFPA) , M. Capalbi (INAF-OAR), M.\nPerri (SSDC & INAF-OAR), S. Lanava (PSU), S. Dichiara (PSU), J.A.\nKennea (PSU) and P.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 7.6 ks of XRT data for GRB 251005C, from 129 s to 29.0\nks after the   trigger. The data are entirely in Photon Counting (PC)\nmode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=1.34 (+/-0.06).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.41 (+0.27, -0.25). The\nbest-fitting absorption column is  7.1 (+2.8, -2.2) x 10^21 cm^-2, in\nexcess of the Galactic value of 3.2 x 10^21 cm^-2 (Willingale et al.\n2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 6.4 x 10^-11 (8.2 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     7.1 (+2.8, -2.2) x 10^21 cm^-2\nGalactic foreground: 3.2 x 10^21 cm^-2\nExcess significance: 2.9 sigma\nPhoton index:\t     1.41 (+0.27, -0.25)\n\nIf the light curve continues to decay with a power-law decay index of\n1.34, the count rate at T+24 hours will be 4.2 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x\n10^-14 (3.5 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01401726.\n\nThis circular is an official product of the Swift-XRT team.\n"
}