{
  "bibcode": "2012GCN.12797....1L",
  "body": "O.M. Littlejohns (U. Leicester), G. Stratta (ASDC), P. D'Avanzo\n(INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), J.A. Kennea (PSU),\nM.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester)\nand F.E. Marshall report on behalf of the Swift-XRT team:\n\nWe have analysed 12 ks of XRT data for GRB 120102A (Marshall  et al.\nGCN Circ. 12794), from 119 s to 34.6 ks after the  BAT trigger. The\ndata comprise 240 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 12795).\n\nThe late-time light curve (from T0+4.5 ks) can be modelled with an\ninitial power-law decay with an index of alpha=1.99 (+0.27, -0.11),\nfollowed by a break at T+13.0 ks to an alpha of 0.97 (+0.27, -0.22).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.04 (+/-0.08). The\nbest-fitting absorption column is  2.59 (+0.26, -0.25) x 10^21 cm^-2,\nin excess of the Galactic value of 1.0 x 10^21 cm^-2 (Kalberla et al.\n2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion\nfactor deduced from this spectrum  is 4.0 x 10^-11 (6.2 x 10^-11) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     2.59 (+0.26, -0.25) x 10^21 cm^-2\nGalactic foreground: 1.0 x 10^21 cm^-2\nExcess significance: 10.3 sigma\nPhoton index:\t     2.04 (+/-0.08)\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00510922.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 12797,
  "createdOn": 1325514484000,
  "email": "pae9@star.le.ac.uk",
  "subject": "GRB 120102A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@star.le.ac.uk>",
  "eventId": "GRB 120102A"
}