{
  "bibcode": "2008GCN..8522....1B",
  "body": "A.P. Beardmore (U. Leicester), D.N. Burrows (PSU), J.R. Cummings (NASA/UMBC) \nreport on behalf of the Swift-XRT team.\n\nThe Swift-XRT reobserved the field of the Swift-BAT and IPN localisation \nGRB 081105 (Cummings et al., GCN 8484) for a further 9.8 ks starting at \n2008-11-12T04:15:51(UT), 6.62 days after the trigger.\n\nUsing a 10 pixel radius extraction region we detect 9 counts at the \nposition of the XRT source reported in GCN 8487 (Beardmore & Cummings) \ncompared with 1.28+/-0.20 estimated background counts. The Bayesian method \nof Kraft et al. (1991 ApJ 374 344) produces a 3 sigma confidence level on \nthe expected source counts of S_min = 1.40 to S_max = 20.08, suggesting \nthe source is detected. (The lower limit on the expected source counts, \nS_min, approaches zero when the confidence level reaches 4.4 sigma.) The \nestimated source count rate is (1.07+/-0.40)e-3 count/s (where the quoted \nerror is 1 sigma), compared with a value of 0.0065 +/-0.0015 count/s from \nthe earlier observation.\n\nBy fitting the low counts per bin data using Cash statistics, we find\nthe source has faded with a decay slope of 1.01 +0.38-0.32. Both the\nsource intensity and decay is comparable to those seen in other long GRBs \nat this stage of their outburst (e.g. see \nhttp://www.swift.ac.uk/xrt_curves/allcurves.php).\n\nWe suggest the X-ray source reported in GCN 8487 was the counterpart to \nthe BAT/IPN localisation and its decaying nature gives further weight to a \nGRB interpretation.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 8522,
  "createdOn": 1226798146000,
  "email": "apb@star.le.ac.uk",
  "subject": "Further Swift-XRT observations of the probable GRB 081105.",
  "submitter": "Andy Beardmore at U Leicester  <apb@star.le.ac.uk>",
  "eventId": "GRB 081105"
}