{
  "bibcode": "2007GCN..6659....1P",
  "body": "K.L Page (U. Leicester) and H. Ziaeepour (UCL-MSSL) report on behalf of \nthe Swift-XRT team:\n\nWe have analysed the first three orbits of Swift-XRT data obtained for GRB \n070724 (Ziaeepour et al., GCN Circ. 6654), which includes ~60 s of \nWindowed Timing (WT) mode data and ~5.2 ks of Photon Counting (PC) data.\n\nUsing 399 s of overlapping XRT PC mode and UVOT V-band data, we find an \nastrometrically corrected X-ray position (using the XRT-UVOT alignment and \nmatching UVOT field sources to the USNO-B1 catalogue) of RA, Dec (J2000) = \n27.80815, -18.59448 which is equivalent to:\n\nRA (J2000):   01 51 13.96\nDec (J2000): -18 35 40.1\n\nwith an uncertainty of 2.2 arcsec (radius, 90% confidence). This is 2.7 \narcsec from the initial XRT position (GCN Circ. 6654) and 77.8 arcsec from \nthe ground-calculated BAT position (Parsons et al., GCN Circ. 6656).\n\nThe first orbit of XRT data shows flaring activity, with the underlying \npower-law decay asserting itself from about 500 seconds after the trigger. \nThis decay slope is poorly constrained with the data currently available: \nalpha ~ 0.4 +0.3/-0.2\n\nFitting the PC data from the second and third orbits (~4-12 ks after the \ntrigger) in order to avoid any spectral evolution during the flares, the \nspectrum can be modelled by a power-law of Gamma = 1.3 +0.8/-0.6, absorbed \nby the Galactic column in this direction of 1.43e20 cm^-2. The 0.3-10 keV \nobserved (unabsorbed) flux during this time is 5.18e-13 (5.27e-13) erg \ncm^-2 s^-1.\n\nIf the decay continues with a slope of alpha ~ 0.4, the count rate at 24 \nhours is predicted to be 4e-3 count s^-1; this ranges between 2e-3 and \n8e-3 count s^-1, taking into account the uncertainties on the slope. Using \nthe spectral fit detailed above, this corresponds to an observed flux of \n(2 +7/-1)e-13 erg cm^-2 s^-1 (over 0.3-10 keV).\n\nThis circular is an official product of the XRT team.",
  "circularId": 6659,
  "createdOn": 1185298198000,
  "email": "kpa@star.le.ac.uk",
  "subject": "GRB 070724: Swift-XRT Team refined analysis",
  "submitter": "Kim Page at U.of Leicester  <kpa@star.le.ac.uk>",
  "eventId": "GRB 070724"
}