{
  "bibcode": "2022GCN.32899....1D",
  "body": "V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D. Gropp (PSU), S.\nDichiara (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester),\nK.L. Page (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai\n(INAF-IASFPA) and A.Y. Lien report on behalf of the Swift-XRT team:\n\nWe have analysed 5.6 ks of XRT data for GRB 221028A (Lien et al. GCN\nCirc. 32874), from 92 s to 28.1 ks after the  BAT trigger. The data\ncomprise 23 s in Windowed Timing (WT) mode (the first 2 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The refined XRT position is RA, Dec = 314.2027, +41.0898 which is\nequivalent to:\n\nRA (J2000): 20 56 48.64\nDec(J2000): +41 05 23.3\n\nwith an uncertainty of 3.5 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with a power-law decay with a decay\nindex of alpha=2.04 (+0.13, -0.12).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.5 (+0.5, -0.4). The\nbest-fitting absorption column is  2.4 (+1.0, -0.8) x 10^22 cm^-2, in\nexcess of the Galactic value of 7.8 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 8.2 x 10^-11 (1.3 x 10^-10) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.4 (+1.0, -0.8) x 10^22 cm^-2\nGalactic foreground: 7.8 x 10^21 cm^-2\nExcess significance: 3.3 sigma\nPhoton index:\t     1.5 (+0.5, -0.4)\n\nIf the light curve continues to decay with a power-law decay index of\n2.04, the count rate at T+24 hours will be 8.3 x 10^-6 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.8 x\n10^-16 (1.1 x 10^-15) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01131910.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 32899,
  "createdOn": 1667201341000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 221028A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 221028A"
}