{
  "bibcode": "2007GCN..6902....1S",
  "body": "B. Sbarufatti, V. Mangano, V. La Parola, E. Troja (INAF-IASFPA),\nP. Evans, A. Beardmore (U Leicester), D. N. Burrows (PSU),\nF. E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team\n\nWe have analysed the first orbits of Swift-XRT data obtained for\nGRB 071011 (trigger=293924, GCN 6882). The observation consists\nof 6.6 ks exposure in Photon Counting (PC) mode, starting 2.7 ks\nafter the trigger. The GRB afterglow is clearly detected inside\nthe XRT field of view (FoV) at a large off axis angle only in the\ninitial 1.6 ks. During the following 5 ks the source was outside\nthe FoV because of an incorrect spacecraft pointing.\nUsing an improved algorithm that takes into account the presence\nof the underlying hot column we obtain a refined position of:\n\nRA, Dec= 8.38816, 61.13327 (degrees)\n\n    RA(J2000)=    00h 33m 33.1s\n    Dec(J2000)=  +61d 07' 59.77\"\n\n\nwith an estimated uncertainty radius of 4.1 arcsec (90% containment\nradius). This is 2.7 arcsec away from the previous XRT position\n(GCN 6891) and 5.5 arcsec away from the optical afterglow reported\nby Cenko (GCN 6895) and Perley et al. (GCN 6898). We note that the\nposition uncertainty of 4.1 arcseconds includes both systematic and\nstatistical uncertainty, but the systematic component may be\nunderestimated for a source this close to the edge of the field of\nview.\n\nThe light curve shows a behavior consistent with a powerlaw decay\nwith slope -1 +/- 0.7. Due to the large uncertainty we need more\ndata to constrain the afterglow evolution.\n\nThe spectrum extracted from the initial 1.6 ks PC data can be\nmodelled with an absorbed  power-law with photon index\nGamma = 2.6 +/- 0.5, and an absorbing column of\nNH = (1.5 +/- 0.7)E22 cm-2, in excess with respect to the Galactic\nvalue of 5.18E21 cm-2. The observed (unabsorbed) flux is\n1.26 (6.00)E-11 ergs cm-2 s-1.\n\nAll errors are quoted at 90% confidence level.\n\nAdditional X-ray observations planned for Oct 14-15 should help\nimprove both the counterpart position accuracy and the measurement\nof the decay rate and spectral parameters.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 6902,
  "createdOn": 1192201679000,
  "email": "sbarufatti@ifc.inaf.it",
  "subject": "GRB 071011: Swift-XRT refined analysis",
  "submitter": "Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti@ifc.inaf.it>",
  "eventId": "GRB 071011"
}