{
  "bibcode": "2012GCN.13326....1K",
  "body": "J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), A.P. Beardmore\n(U. Leicester), P.A. Evans (U. Leicester), O.M. Littlejohns (U.\nLeicester), V. D'Elia (ASDC), A. Maselli  (INAF-IASFPA), V. Mangano\n(INAF-IASFPA) and M.M. Chester report on behalf of the Swift-XRT team:\n\nWe have analysed 4.3 ks of XRT data for GRB 120521A (Chester  et al.\nGCN Circ. 13302), from 83 s to 11.3 ks after the  BAT trigger. The data\nare entirely in Photon Counting (PC) mode. The enhanced XRT position\nfor this burst was given by Goad et al. (GCN. Circ 13304).\n\nThe light curve can be modelled with  a power-law decay with a decay\nindex of alpha=anf (+/anf).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.81 (+0.36, -0.29). The\nbest-fitting absorption column is  2.6 (+1.4, -0.5) x 10^21 cm^-2,\nconsistent with the Galactic value of 2.1 x 10^21 cm^-2 (Kalberla et\nal. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux\nconversion factor deduced from this spectrum  is 4.6 x 10^-11 (6.3 x\n10^-11) erg cm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.6 (+1.4, -0.5) x 10^21 cm^-2\nGalactic foreground: 2.1 x 10^21 cm^-2\nExcess significance: <1.6 sigma\nPhoton index:\t     1.81 (+0.36, -0.29)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00522578.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 13326,
  "createdOn": 1337670900000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 120521A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 120521A"
}