{
  "bibcode": "2007GCN..6598....1G",
  "body": "O. Godet (U. Leicester) & T. Sakamoto (GSFC/ISAS) report on behalf the\nSwift/XRT team\n\nWe have analysed the first 8.5ks of Swift XRT PC and WT data of GRB\n070704 (Sakamoto et al., GCN Circ. 6594) taken from T0+153s to T0+3e4s. \nUsing 129 s of overlapping XRT Photon Counting mode and UVOT V-band\ndata, we find an astrometrically corrected X-ray position (using the\nXRT-UVOT alignment and matching UVOT field sources to the USNO-B1\ncatalogue): RA, Dec = 354.69915, +66.25328 which is equivalent to:\n\nRA (J2000):  23 38 47.80\nDec (J2000): +66 15 11.8\n\nwith an uncertainty of 2.7 arcsec (90% confidence). This is 3.7 arcsec\nfrom the initially reported XRT position and 39.4 arcsec from the BAT\nposition (GCN Circ. 6594).\n\nThe XRT light curve exhibits an initial decay on which is superposed a\nlarge flare peaking around T0+300s. We note that between T0+250s and T0\n+410s an emission was also detected in the BAT (Markwardt et al., GCN\nCirc. 6596). The light-curve from T0+600s to T0+3e4s is fit well by a\npower-law with a decay index of 0.87 +0.11/-0.12. \n\nThe spectrum of the WT data from T0+153s to T0+527s is fit well by an\nabsorbed power-law with a photon index of 1.85 +/-0.06 and column\ndensity of N_H = (1.08+/-0.06)e22 cm^-2 in excess of the Galactic value\n(8.6E21 cm^-2; Dickey & Lockman, 1990). The absorbed (unabsorbed)\n0.3-10.0keV flux for that spectrum is (1.57+/-0.05)E-9 (2.85E-9) ergs\ncm^-2 s^-1. The spectrum of the PC data from T0+530s to T0+3e4s is fit\nwell by an absorbed power-law with a photon index of 1.97+/-0.27 with\nN_H fixed at 1.08e22 cm^-2. The absorbed (unabsorbed) 0.3-10.0keV flux\nfor that spectrum is (3.3 +0.6/-0.8)E-12 (6.54E-12) ergs cm^-2 s^-1.\n\nAssuming the source continues to decay at the same rate, we predict an\nXRT count rate of 0.0044 counts/s at T0+24 hours, which corresponds to\nan observed (unabsorbed) flux of 6.2E-13 (2.9E-12) ergs cm^-2 s^-1.\n\nThis circular is an official product of the Swift XRT team.",
  "circularId": 6598,
  "createdOn": 1183635829000,
  "email": "og19@star.le.ac.uk",
  "subject": "GRB 070704: Swift-XRT refined analysis",
  "submitter": "Olivier Godet at U.of Leicester  <og19@star.le.ac.uk>",
  "eventId": "GRB 070704"
}