{
  "bibcode": "2013GCN.15523....1B",
  "body": "A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), B.P. Gompertz\n(U. Leicester), A. Maselli  (INAF-IASFPA), A. Melandri (INAF-OAB), B.\nSbarufatti (INAF-OAB/PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.A.\nKennea (PSU) and C.B. Markwardt report on behalf of the Swift-XRT team:\n\nWe have analysed 6.5 ks of XRT data for GRB 131127A (Markwardt\tet al.\nGCN Circ. 15516),  from 84 s to 24.3 ks after the  BAT trigger. The\ndata comprise 62 s in Windowed Timing (WT) mode (the first 8 s were\ntaken while Swift was slewing) with the remainder in Photon Counting\n(PC) mode. The enhanced XRT position for this burst was given by Evans\net al. (GCN. Circ 15520).\n\nThe late-time light curve (from T0+4.5 ks) can be modelled with  a\npower-law decay with a decay index of alpha=1.55 (+0.26, -0.22).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 3.8 (+0.4, -0.3). The\nbest-fitting absorption column is  3.9 (+0.7, -0.6) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.2 x 10^21 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 2.22 (+/-0.15) and a\nbest-fitting absorption column of 2.5 (+0.5, -0.4) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.6 x 10^-11 (6.1 x 10^-11) erg cm^-2\ncount^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.5 (+0.5, -0.4) x 10^21 cm^-2\nGalactic foreground: 1.2 x 10^21 cm^-2\nExcess significance: 5.1 sigma\nPhoton index:\t     2.22 (+/-0.15)\n\nIf the light curve continues to decay with a power-law decay index of\n1.55, 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 8.0 x\n10^-14 (1.4 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/00579571.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 15523,
  "createdOn": 1385591583000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 131127A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 131127A"
}