{
  "body": "A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai\n(INAF-IASFPA), A. Melandri (INAF-OAR), J. D. Gropp (PSU), S. Dichiara\n(PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester) and P.A. Evans\nreport on behalf of the Swift-XRT team:\n\nWe have analysed 7.9 ks of XRT data for GRB 230802A, from 52 s to 40.1\nks after the  BAT trigger. The data comprise 386 s in Windowed Timing\n(WT) mode (the first 10 s were taken while Swift was slewing) with the\nremainder in Photon Counting (PC) mode. \n\nThe light curve can be modelled with a series of power-law decays. The\ninitial decay index is alpha=0.4 (+/-0.4). At T+345 s  the decay\nsteepens to an alpha of 2.5 (+0.4, -0.3) before breaking again at\nT+1364 s to a final decay with index alpha=1.26 (+0.16, -0.30).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.02 (+/-0.04). The\nbest-fitting absorption column is  6.5 (+/-0.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 3.4 x 10^21 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.66 (+0.22, -0.21)\nand a best-fitting absorption column of 4.5 (+1.5, -1.1) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 4.9 x 10^-11 (6.5 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     4.5 (+1.5, -1.1) x 10^21 cm^-2\nGalactic foreground: 3.4 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.66 (+0.22, -0.21)\n\nIf the light curve continues to decay with a power-law decay index of\n1.26, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.2 x\n10^-14 (9.7 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/01182085.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "createdOn": 1691008109847,
  "bibcode": "2023GCN.34318....1B",
  "subject": "GRB 230802A: Swift-XRT refined Analysis",
  "circularId": 34318,
  "eventId": "GRB 230802A",
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "submittedHow": "email"
}