{
  "bibcode": "2010GCN.10829....1L",
  "body": "O. Littlejohns, P. A. Evans, J. P. Osborne (U. Leicester) and S. R.\nOates (UCL-MSSL) report on behalf of the Swift-XRT team:\n\nWe have analysed 4.9 ks of XRT data for GRB 100606A (Oates et al. GCN\nCirc. 10824), from 86 s to 19.1 ks after the BAT trigger. The data\ncomprise 313 s in Windowed Timing (WT) mode (the first 9 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Evans et al.\n(GCN. Circ 10825).\n\nThe light curve can be modelled with a series of power-law decays. The\nlight curve initially shows some flaring with an underlying decay index\nof 1.69 (+0.14, -0.10) from T+138 s to T+455 s. The light curve then\nbreaks at T+455 s to a decay with alpha=0.88 (+0.15, -0.26), flares may\nalso be present in this interval, before a final break at T+1641 s after\nwhich the decay index is 2.09 (+1.28, -0.16).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.61 (+/-0.08). The\nbest-fitting absorption column is 2.06 (+0.29, -0.28) x 10^21 cm^-2, in\nexcess of the Galactic value of 2.4 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 1.91 (+0.15, -0.14)\nand a best-fitting absorption column of 2.2 (+0.5, -0.4) x 10^21 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 4.4 x 10^-11 (6.2 x 10^-11) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n2.09, the count rate at T+24 hours will be 2.9 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x\n10^-14 (1.8 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00424031.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10829,
  "createdOn": 1275901786000,
  "email": "oml2@star.le.ac.uk",
  "subject": "GRB 100606A Swift-XRT refined analysis",
  "submitter": "Owen Littlejohns at U of Leicester  <oml2@star.le.ac.uk>",
  "eventId": "GRB 100606A"
}