{
  "circularId": 34995,
  "createdOn": 1699764444685,
  "body": "J.P. Osborne (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti\n(INAF-OAB), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp\n(PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) and P.A. Evans\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 7.3 ks of XRT data for GRB 231111A, from 93 s to 39.7\nks after the  BAT trigger. The data comprise 296 s in Windowed Timing\n(WT) mode (the first 5 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe late-time light curve (from T0+16.2 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.03 (+/-0.23).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 2.47 (+0.10, -0.06). The\nbest-fitting absorption column is  1.297 (+0.206, -0.027) x 10^21\ncm^-2, consistent with the Galactic value of 1.3 x 10^21 cm^-2\n(Willingale et al. 2013). The PC mode spectrum has a photon index of\n1.98 (+0.19, -0.18) and a best-fitting absorption column of 1.6 (+0.6,\n-0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV\nflux conversion factor deduced from this spectrum  is 3.5 x 10^-11 (4.6\nx 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.6 (+0.6, -0.3) x 10^21 cm^-2\nGalactic foreground: 1.3 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.98 (+0.19, -0.18)\n\nIf the light curve continues to decay with a power-law decay index of\n1.03, the count rate at T+24 hours will be 0.029 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 10.0 x\n10^-13 (1.3 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/01195887.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "subject": "GRB 231111A: Swift-XRT refined Analysis",
  "bibcode": "2023GCN.34995....1O",
  "submittedHow": "email",
  "eventId": "GRB 231111A"
}