{
  "bibcode": "2012GCN.14112....1L",
  "body": "O.M. Littlejohns (U. Leicester), B. Sbarufatti (INAF-OAB/PSU), G.\nStratta (ASDC), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J.A. Kennea\n(PSU), M.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.\nLeicester) and H.A. Krimm report on behalf of the Swift-XRT team:\n\nWe have analysed 10 ks of XRT data for GRB 121226A (Krimm  et al. GCN\nCirc. 14105),  from 109 s to 35.4 ks after the\tBAT trigger. The data\nare entirely in Photon Counting (PC) mode. The best available XRT\nposition  (using the promptly downlinked event data, the XRT-UVOT\nalignment and matching UVOT field sources to the USNO-B1 catalogue) is\nRA, Dec = 168.6423, -30.4064 which is equivalent to:\n\nRA (J2000): 11 14 34.14\nDec(J2000): -30 24 23.1\n\nwith an uncertainty of 2.1 arcsec (radius, 90% confidence).\n\nThe light curve can be modelled with  a power-law decay with a decay\nindex of alpha=0.98 (+/-0.06).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.4 (+/-0.4). The\nbest-fitting absorption column is  8.2 (+2.5, -2.1) x 10^21 cm^-2, in\nexcess of the Galactic value of 6.1 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 4.4 x 10^-11 (1.2 x 10^-10) erg\ncm^-2 count^-1. \n\nA summary of the PC-mode spectrum is thus:\nTotal column:\t     8.2 (+2.5, -2.1) x 10^21 cm^-2\nGalactic foreground: 6.1 x 10^20 cm^-2\nExcess significance: 6.0 sigma\nPhoton index:\t     2.4 (+/-0.4)\n\nIf the light curve continues to decay with a power-law decay index of\n0.98, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.7 x\n10^-14 (1.9 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/00544027.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 14112,
  "createdOn": 1356632644000,
  "email": "pae9@leicester.ac.uk",
  "subject": "GRB 121226A: Swift-XRT refined Analysis",
  "submitter": "Phil Evans at U of Leicester  <pae9@leicester.ac.uk>",
  "eventId": "GRB 121226A"
}