{
  "bibcode": "2012GCN.13249....1S",
  "body": "B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo\n(INAF-OAB), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU),\nJ.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.\nLeicester) and E. Troja report on behalf of the Swift-XRT team:\n\nWe have analysed 13 ks of XRT data for GRB 120422A (Troja  et al. GCN\nCirc. 13243), from 101 s to 30.1 ks after the  BAT trigger. The data\ncomprise 307 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The enhanced XRT position for this burst was\ngiven by Beardmore et al. (GCN. Circ 13247).\n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=6.22 (+0.30, -0.28), followed by a break at T+373 s to\nan alpha of 0.30 (+0.11, -0.14).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 4.5 (+0.4, -0.3). The\nbest-fitting absorption column is  2.5 (+0.5, -0.4) x 10^21 cm^-2, in\nexcess of the Galactic value of 3.7 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 1.9 x 10^-11 (1.7 x 10^-10) erg\ncm^-2 count^-1. \n\nA summary of the WT-mode spectrum is thus:\nTotal column:\t     2.5 (+0.5, -0.4) x 10^21 cm^-2\nGalactic foreground: 3.7 x 10^20 cm^-2\nExcess significance: 8.5 sigma\nPhoton index:\t     4.5 (+0.4, -0.3)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00520658.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 13249,
  "createdOn": 1335122585000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 120422A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 120422A"
}