{
  "submitter": "Phil Evans at U of Leicester <pae9@star.le.ac.uk>",
  "eventId": "GRB 250322A",
  "body": "M. Perri (SSDC & INAF-OAR), J.A. Kennea (PSU), D.N. Burrows (PSU), M.\nA. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.\nLeicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB) and\nP.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 3.7 ks of XRT data for GRB 250322A, from 58 s to 22.2\nks after the  BAT trigger. The data comprise 7 s in Windowed Timing\n(WT) mode (taken while Swift was slewing), with the remainder in Photon\nCounting (PC) mode. \n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=2.28 (+0.18, -0.17).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.09 (+0.49, -0.26). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 2.7 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 3.6 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.7 (+/-2.3) x 10^21 cm^-2\nGalactic foreground: 2.7 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     2.09 (+0.49, -0.26)\n\nIf the light curve continues to decay with a power-law decay index of\n2.28, the count rate at T+24 hours will be 2.2 x 10^-7 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.9 x\n10^-18 (1.2 x 10^-17) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01297832.\n\nThis circular is an official product of the Swift-XRT team.\n",
  "createdOn": 1742748859437,
  "submittedHow": "email",
  "bibcode": "2025GCN.39855....1P",
  "circularId": 39855,
  "subject": "GRB 250322A: Swift-XRT refined Analysis"
}