{
  "bibcode": "2018GCN.22322....1L",
  "body": "S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU),\nA.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), S.L. Gibson\n(U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai\n(INAF-IASFPA) and A.Y. Lien report on behalf of the Swift-XRT team:\n\nWe have analysed 6.1 ks of XRT data for GRB 180111A (Lien et al. GCN\nCirc. 22318), from 94 s to 23.6 ks after the  BAT trigger. The data\ncomprise 117 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Evans et al. (GCN Circ. 22319).\n\nThe late-time light curve (from T0+4.0 ks) can be modelled with a\npower-law decay with a decay index of alpha=1.46 (+0.38, -0.29).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.48 (+/-0.09). The\nbest-fitting absorption column is  4.0 (+3.0, -2.6) x 10^20 cm^-2, in\nexcess of the Galactic value of 1.1 x 10^20 cm^-2 (Willingale et al.\n2013). The PC mode spectrum has a photon index of 1.66 (+0.21, -0.12)\nand a best-fitting absorption column of 1.17 (+4.88, -0.09) x 10^20\ncm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.8 x 10^-11 (3.9 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.17 (+4.88, -0.09) x 10^20 cm^-2\nGalactic foreground: 1.1 x 10^20 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.66 (+0.21, -0.12)\n\nIf the light curve continues to decay with a power-law decay index of\n1.46, the count rate at T+24 hours will be 9.2 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.5 x\n10^-14 (3.6 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00804692.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 22322,
  "createdOn": 1515720341000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 180111A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 180111A"
}