{
  "bibcode": "2019GCN.23857....1K",
  "body": "J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.\nLeicester), P.A. Evans (U. Leicester), V. D'Elia (ASDC), A. D'Ai\n(INAF-IASFPA), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU),\nD.N. Burrows (PSU) and A.Y. Lien report on behalf of the Swift-XRT\nteam:\n\nWe have analysed 6.4 ks of XRT data for GRB 190204A (Lien et al. GCN\nCirc. 23852), from 81 s to 13.0 ks after the  BAT trigger. The data\ncomprise 926 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The refined XRT position is RA, Dec =\n351.4775, +54.8766 which is equivalent to:\n\nRA (J2000): 23 25 54.59\nDec(J2000): +54 52 35.7\n\nwith an uncertainty of 3.6 arcsec (radius, 90% confidence).\n\nThe late-time light curve (from T0+4.8 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.36 (+/-0.16).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.740 (+0.022, -0.018). The\nbest-fitting absorption column is  consistent with the Galactic value\nof 4.4 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has\na photon index of 1.83 (+0.12, -0.11) and a best-fitting absorption\ncolumn of 5.4 (+0.8, -0.7) x 10^21 cm^-2. The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 4.6 x 10^-11 (6.8 x 10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     5.4 (+0.8, -0.7) x 10^21 cm^-2\nGalactic foreground: 4.4 x 10^21 cm^-2\nExcess significance: 2.4 sigma\nPhoton index:\t     1.83 (+0.12, -0.11)\n\nIf the light curve continues to decay with a power-law decay index of\n1.36, the count rate at T+24 hours will be 9.9 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x\n10^-13 (6.8 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/00887579.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 23857,
  "createdOn": 1549280754000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 190204A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 190204A"
}