{
  "bibcode": "2007GCN..6963....1P",
  "body": "K.L. Page (U Leicester), N. Gehrels (NASA/GSFC) and T. Sakamoto \n(NASA/UMBC) report on behalf of the Swift-XRT team:\n\nWe have analysed three orbits of Swift-XRT data obtained for GRB 071021 \n(Sakamoto et al. GCN Circ. 6958), totalling 1.7 ks of Windowed Timing (WT) \ndata and 5.3 ks of Photon Counting (PC) data. Using the PC data we derive \na refined position of RA, Dec = 340.64311, +23.71808, which is equivalent \nto\n\nRA(J2000)  =  22 42 34.35\nDec(J2000) = +23 43 05.1\n\nwith an estimated error radius of 3.9 arcsec (90 percent containment). \nThis is 4.8 arcsec from the onboard XRT position given by Sakamoto et al. \nin GCN Circ. 6958). The position is also 15.1 arcsec from the Faulkes \nTelescope South optical candidate (Guidorzi et al., GCN Circ. 6959) and \ntherefore not consistent with it.\n\nThe X-ray light-curve is initially quite flat, remaining at around 40-50 \ncount s^-1 until 230 seconds after the trigger. There follows a very steep \ndecay, until about 700 seconds post-trigger, when a series of strong \nflares are seen; this behaviour continues into the second orbit, with the \nthird orbit showing the afterglow emission has decayed further.\n\nThere is spectral evolution during the initial light-curve, although the \nWT data before the steep decay (135-245 seconds) can be modelled as an \nabsorbed power-law, with Gamma = 2.12 +/- 0.09 and a total absorbing \ncolumn of NH = (1.8 +/- 0.2)e21 cm^-2, considerably in excess of the \nGalactic value of 4.8e20 cm^-2. The 0.3-10 keV observed (unabsorbed) flux \nduring this time is 1.3e-10 (1.9e-10) erg cm^-2 s^-1.\n\nBecause of the flaring activity, it is not feasible accurately to predict \na count-rate at 24 hours.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 6963,
  "createdOn": 1192987132000,
  "email": "kpa@star.le.ac.uk",
  "subject": "GRB 071021: Swift-XRT Team refined analysis",
  "submitter": "Kim Page at U.of Leicester  <kpa@star.le.ac.uk>",
  "eventId": "GRB 071021"
}