{
  "subject": "GRB 260101A: Swift-XRT refined Analysis",
  "createdOn": 1767269505380,
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 260101A",
  "submittedHow": "email",
  "bibcode": "2026GCN.43291....1D",
  "body": "P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), S. Lanava (PSU), S.\nDichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L.\nPage (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi \n(INAF-IASFPA)  and P.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 6.7 ks of XRT data for GRB 260101A, from 100 s to 28.9\nks after the   trigger. The data comprise 165 s in Windowed Timing (WT)\nmode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe late-time light curve (from T0+5.3 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.65 (+/-0.17).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.02 (+0.16, -0.15). The\nbest-fitting absorption column is  2.1 (+/-0.5) x 10^21 cm^-2,\nconsistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et\nal. 2013). The PC mode spectrum has a photon index of 1.91 (+0.16,\n-0.15) and a best-fitting absorption column of 2.2 (+0.6, -0.5) x 10^21\ncm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.8 x 10^-11 (5.1 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.2 (+0.6, -0.5) x 10^21 cm^-2\nGalactic foreground: 1.6 x 10^21 cm^-2\nExcess significance: 1.8 sigma\nPhoton index:\t     1.91 (+0.16, -0.15)\n\nIf the light curve continues to decay with a power-law decay index of\n1.65, the count rate at T+24 hours will be 3.9 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x\n10^-13 (2.0 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttps://www.swift.ac.uk/xrt_products/01429608.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "circularId": 43291
}