{
  "bibcode": "2018GCN.22530....1O",
  "body": "J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia\n(ASDC), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), D.N. Burrows\n(PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), A.P. Beardmore (U.\nLeicester) and E. Sonbas report on behalf of the Swift-XRT team:\n\nWe have analysed 7.1 ks of XRT data for GRB 180324A (Sonbas et al. GCN\nCirc. 22524), from 80 s to 13.9 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. 22525).\n\nThe late-time light curve (from T0+5.7 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.07 (+/-0.16).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.36 (+0.13, -0.12). The\nbest-fitting absorption column is  9.0 (+1.6, -1.4) x 10^21 cm^-2, in\nexcess of the Galactic value of 3.8 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 6.7 x 10^-11 (8.7 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     9.0 (+1.6, -1.4) x 10^21 cm^-2\nGalactic foreground: 3.8 x 10^21 cm^-2\nExcess significance: 5.9 sigma\nPhoton index:\t     1.36 (+0.13, -0.12)\n\nIf the light curve continues to decay with a power-law decay index of\n1.07, the count rate at T+24 hours will be 0.032 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x\n10^-12 (2.8 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00817345.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 22530,
  "createdOn": 1521886771000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 180324A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 180324A"
}