{
  "bibcode": "2007GCN..6738....1P",
  "body": "K.L. Page, P.A. Evans (U. Leicester), M.M Chester (PSU) and J.R. Cummings \n(NASA/UMBC) report on behalf of the Swift-XRT team:\n\nWe have analysed the first four orbits of Swift-XRT data obtained for GRB \n070810 (Cummings et al., GCN Circ. 6733), totalling 7.9 ks of Photon \nCounting (PC) mode data. The enhanced XRT position was given by Evans et \nal. in GCN Circ. 6736, and is 1.7 arcsec from the fading UVOT source \n(Chester et al., GCN Circ. 6735).\n\nThe X-ray light-curve is almost flat for the first orbit of PC data, with \nalpha = 0.30 +0.18/-0.20. About 1.1 ks after the trigger, the decay \nsteepened to a slope of 1.1 +/- 0.2.\n\nFitting the PC data from the second to fourth orbits (i.e. after the \nbreak; 3.8-17.8 ks after the trigger), the spectrum can be modelled by an \nabsorbed power-law with Gamma = 2.3 +/- 0.3 and NH = (1.3 +/- 0.5)e21 \ncm^-2, in excess of the Galactic value of 1.75e20 cm^-2. The 0.3-10 keV \nobserved (unabsorbed) flux during this time is 2.17e-12 (3.34e-12) erg \ncm^-2 s^-1.\n\nIf the decay continues with a slope of alpha ~ 1.1, the predicted count \nrate at 24 hours is 4.1e-3 count s^-1. Using a flux conversion factor \n(determined from the post-break spectrum described above) of 1 count s^-1 \n~ 4e-11 erg cm^-2 s^-1 (observed) and 5.8e-11 erg cm^-2 s^-1 (unabsorbed), \nthis corresponds to an observed (unabsorbed) flux of 1.6e-13 (2.4e-13) erg \ncm^-2 s^-1.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 6738,
  "createdOn": 1186740077000,
  "email": "kpa@star.le.ac.uk",
  "subject": "GRB 070810: Swift-XRT Team Refined Analysis",
  "submitter": "Kim Page at U.of Leicester  <kpa@star.le.ac.uk>",
  "eventId": "GRB 070810"
}