{
  "bibcode": "2007GCN..6955....1B",
  "body": "A.P. Beardmore, K.L. Page, P.A. Evans (U. Leicester) and S.T. Holland\n(CRESST/USRA/GSFC) report on behalf of the Swift-XRT team:\n\nThe Swift-XRT began observing the BAT GRB 071020 (trigger #294835) at\n07:03:28 UT, 61 seconds after the BAT trigger.  In a 1.23ks\nexposure Photon Counting mode image obtained during the first orbit\nwe find a refined XRT position of RA, Dec (J2000) = 119.66521, 32.86079 \nwhich is\n\nRA(J2000)  =  07:58:39.65\nDec(J2000) = +32:51:38.8\n\nwith an estimated uncertainty of 4.0 arcsec (radius, 90 percent\ncontainment).  This is 13.9 arcsec from the refined BAT position\n(Tueller et al., GCN 6954), 4.1 arcsec from the position\nof the ROTSE-IIIb afterglow (Schaefer et al., GCN 6948), and\n2.3 arcsec from the PAIRITEL position (Bloom et al., GCN 6953).\n\nDue to a high CCD operating temperature caused by the unfavourable sky\nposition of the burst, along with bright Earth activated hot-pixels,\nthe XRT remained in Windowed Timing mode for orbits 2 to 5 at which\npoint the initial Swift observations were halted for today. However,\nusing the XRT data available at these times, the 0.3-10.0keV X-ray\nlight curve from T+68s to T+17.6ks shows a powerlaw decline with a\ndecay index of 1.11+/0.02.\n\nThe Windowed Timing mode spectrum from the first orbit (T+68s to\nT+315s) is well fit by an absorbed powerlaw with a photon index of\n1.86+/-0.07 and a redshifted column density of (4.3+/-1.7)e21 cm^-2\n(at z=2.145, Jakobsson et al., GCN 6952), in addition to the 5.1e20\ncm^-2 galactic column density in this direction. The observed 0.3-10.0\nkeV flux during this time is (6.1+/-0.2)e-10 erg cm^-2 s^-1.\n\nAssuming the X-ray light curve decays at the same rate we predict an\nXRT count rate of 0.014 count s^-1 at T+24 hours, which corresponds to an\nobserved 0.3-10keV flux of 6.0e-13 erg cm^-2 s^-1.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 6955,
  "createdOn": 1192907018000,
  "email": "apb@star.le.ac.uk",
  "subject": "GRB 071020: Swift-XRT refined analysis",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 071020"
}