{
  "bibcode": "2018GCN.22808....1D",
  "body": "A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), A. Tohuvavohu (PSU), S.\nJ. LaPorte (PSU), J.A. Kennea (PSU), S.L. Gibson (U. Leicester), Z. Liu\n(NAOC / U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo\n(INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team:\n\nWe have analysed 9.6 ks of XRT data for GRB 180620A (Evans et al. GCN\nCirc. 22798), from 274 s to 23.4 ks after the  BAT trigger. The data\nare entirely in Photon Counting (PC) mode. The enhanced XRT position\nfor this burst was given by Osborne et al. (GCN Circ. 22802).\n\nThe late-time light curve (from T0+6.1 ks) can be modelled with a\npower-law decay with a decay index of alpha=2.16 (+/-0.13).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.46 (+0.10, -0.08). The\nbest-fitting absorption column is  1.76 (+0.43, -0.16) x 10^21 cm^-2,\nconsistent with the Galactic value of 1.6 x 10^21 cm^-2 (Willingale et\nal. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.9 x 10^-11 (5.6 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.76 (+0.43, -0.16) x 10^21 cm^-2\nGalactic foreground: 1.6 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.46 (+0.10, -0.08)\n\nIf the light curve continues to decay with a power-law decay index of\n2.16, the count rate at T+24 hours will be 2.3 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x\n10^-13 (1.3 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/00843122.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 22808,
  "createdOn": 1529514182000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 180620A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 180620A"
}