{
  "bibcode": "2019GCN.23858....1B",
  "body": "A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne\n(U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P.\nD'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU),\nA. Tohuvavohu (PSU) and A.Y. Lien report on behalf of the Swift-XRT\nteam:\n\nWe have analysed 6.5 ks of XRT data for GRB 190203A (Lien et al. GCN\nCirc. 23845), from 103 s to 50.0 ks after the  BAT trigger. The data\ncomprise 669 s in Windowed Timing (WT) mode (the first 8 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Goad et al.\n(GCN Circ. 23848).\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=1.73 (+/-0.08).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.69 (+/-0.04). The\nbest-fitting absorption column is  7.2 (+/-0.5) x 10^21 cm^-2, in\nexcess of the Galactic value of 4.0 x 10^21 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.63 (+0.21, -0.20)\nand a best-fitting absorption column of 6.9 (+2.0, -1.7) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 5.4 x 10^-11 (7.6 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     6.9 (+2.0, -1.7) x 10^21 cm^-2\nGalactic foreground: 4.0 x 10^21 cm^-2\nExcess significance: 2.8 sigma\nPhoton index:\t     1.63 (+0.21, -0.20)\n\nIf the light curve continues to decay with a power-law decay index of\n1.73, the count rate at T+24 hours will be 0.012 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.4 x\n10^-13 (8.9 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/00887512.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 23858,
  "createdOn": 1549282155000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 190203A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 190203A"
}