{
  "bibcode": "2012GCN.13361....1B",
  "body": "D.N. Burrows (PSU), O.M. Littlejohns (U. Leicester), J.P. Osborne (U.\nLeicester), K.L. Page (U. Leicester), V. Mangano (INAF-IASFPA), A.\nMelandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), J.A. Kennea (PSU),\nM.C. Stroh (PSU) and C. Pagani report on behalf of the Swift-XRT team:\n\nWe have analysed 13 ks of XRT data for GRB 120612A (Pagani  et al. GCN\nCirc. 13357), from 144 s to 30.4 ks after the  BAT trigger. The data\ncomprise 91 s in Windowed Timing (WT) mode with the remainder in Photon\nCounting (PC) mode. The enhanced XRT position for this burst was given\nby Evans et al. (GCN. Circ 13359).\n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=3.27 (+0.26, -0.22), followed by a break at T+485 s to\nan alpha of 0.90 (+0.11, -0.10).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.20 (+0.23, -0.22). The\nbest-fitting absorption column is  1.9 (+/-0.6) x 10^21 cm^-2, in\nexcess of the Galactic value of 5.5 x 10^20 cm^-2 (Kalberla et al.\n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 3.5 x 10^-11 (5.5 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     1.9 (+/-0.6) x 10^21 cm^-2\nGalactic foreground: 5.5 x 10^20 cm^-2\nExcess significance: 3.9 sigma\nPhoton index:\t     2.20 (+0.23, -0.22)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00524128.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 13361,
  "createdOn": 1339510684000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 120612A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 120612A"
}