{
  "bibcode": "2021GCN.30192....1B",
  "body": "D.N. Burrows (PSU), J. D. Gropp (PSU), A.P. Beardmore (U. Leicester),\nP.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), T. Sbarrato\n(INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J.A.\nKennea (PSU) and K.L. Page report on behalf of the Swift-XRT team:\n\nWe have analysed 7.1 ks of XRT data for GRB 210610A (Page et al. GCN\nCirc. 30160), from 97 s to 45.9 ks after the  BAT trigger. The data are\nentirely in Photon Counting (PC) mode. The enhanced XRT position for\nthis burst was given by Goad et al. (GCN Circ. 30165).\n\nThe late-time light curve (from T0+4.1 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.05 (+/-0.10).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.84 (+0.12, -0.10). The\nbest-fitting absorption column is  2.6 (+9.0, -2.6) x 10^21 cm^-2, at a\nredshift of 3.54, in addition to the Galactic value of 2.2 x 10^20\ncm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed)\n0.3-10 keV flux conversion factor deduced from this spectrum  is 3.5 x\n10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nGalactic foreground: 2.2 x 10^20 cm^-2\nIntrinsic column:    2.6 (+9.0, -2.6) x 10^21 cm^-2 at z=3.54\nPhoton index:\t     1.84 (+0.12, -0.10)\n\nIf the light curve continues to decay with a power-law decay index of\n1.05, the count rate at T+24 hours will be 9.7 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.4 x\n10^-13 (3.6 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/01054627.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 30192,
  "createdOn": 1623392476000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 210610A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 210610A"
}