{
  "bibcode": "2007GCN..6118....1B",
  "body": "A.P. Beardmore (U. Leicester), M. Stamatikos (NASA/ORAU), P.A. Evans,\nM.R. Goad, O. Godet, K.L. Page, (U. Leicester), M. Capalbi (ASDC),\nJ.P. Osborne, R.L.C. Starling (U. Leicester) report on behalf of the \nSwift-XRT team:\n\nWe have analysed the first two orbits of Swift-XRT data available for\nGRB 070220 (Stamatikos et al., GCN 6114), which were obtained prior to\nthe satellite entering the Malindi Gap.  The data consist of 217s\nexposure in Windowed Timing (WT) mode and 4090s in Photon Counting\n(PC) mode.\n\nUsing the PC data, we find a refined XRT position, which has been\nastrometrically corrected by matching the UVOT images with the\nUSNO-B1 catalogue, of:\n\nRA(J2000)  =  02h 19m 06.83s\nDEC(J2000) = +68d 48' 16.1\"\n\nwith an uncertainty of 2.0 arcseconds (90% confidence). This position\nis 72.0 arcseconds and 3.0 arcseconds away from the original BAT and\nXRT positions quoted in GCN 6114.\n\nThe 0.3-10.0 keV X-ray light curve out to T+7.6ks (where T is the BAT\ntrigger time) can be fit by a broken powerlaw, with an initial decay\nslope of 1.76+/-0.06, a break time of 417+/-43s, and a post-break\nslope of 0.99+/-0.04.\n\nThe WT spectrum from T+85s to T+294s can be modelled by an absorbed\npowerlaw, with a photon index of 1.55+/-0.08 and a column density of\n(4.9+/-0.5)e21 cm^-2 (compared with the Galactic value in this\ndirection of 3.8e21 cm^-2).  The 0.3-10.0 keV observed flux over this\ntime interval is (1.21+/-0.05)e-9 ergs cm^-2 s^-1, which corresponds\nto an unabsorbed flux of (1.65+/-0.10)e-9 ergs cm^-2 s^-1.\n\nWhile the temporal decay parameters are uncertain based on such\nlimited data, assuming the source continues to fade at the same rate\nwe predict an X-ray count rate of 0.019 count/s at T+24 hours, which\ncorresponds to an observed (unabsorbed) 0.3-10.0 keV flux of 1.4e-12\n(1.9e-12) ergs cm^2 s^-1.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 6118,
  "createdOn": 1171976683000,
  "email": "apb@star.le.ac.uk",
  "subject": "GRB 070220: Swift-XRT Refined Analysis",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 070220"
}