{
  "bibcode": "2010GCN.10935....1G",
  "body": "D. Grupe (PSU) reports on behalf of the Swift-XRT team:\n\nWe have analyzed 6162 s of XRT data for GRB 100704A (Grupe  et al.\nGCN Circ. 10929), from 92 s to 18.5 ks  after the  BAT trigger.\nThe data comprise 317 s in Windowed Timing (WT) mode with the\nremainder in Photon Counting (PC) mode. The X-ray light curve displays\na strong flare starting at about 140s and peaking at 190s after the\nburst. As mentioned in GCN Circ. 10929, this flare coincides with a\nflare seen in the BAT. The rest of the light curve can be  modeled\nwith a series of power-law decays. After the flare the afterglow\ndecays with a slope of 0.32 and breaks at about 1 ks after the burst\nfollowed  by a decay slope of 0.76+/-0.06.\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index\tof 1.96 (+/-0.04). The\nbest-fitting absorption column is  3.23 (+/-0.14) x 10^21 cm^-2, in\nexcess of the Galactic value of 1.0 x 10^21 cm^-2 (Kalberla et al.\n2005). With an excess absorption column density of 2.32 x 10^21 cm^-2\nthe NH-redshift relation by Grupe et al. (2007, AJ 133, 2216)\nsuggests a redshift z<3.0.\nThe PC mode spectrum has a photon index of 2.6 (+/-0.3) and a\nbest-fitting absorption column of 3.1 (+0.9, -0.8) x 10^21 cm^-2. The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum  is 3.5 x 10^-11 (8.3 x 10^-11) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.76, the count rate at T+24 hours will be 0.045 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x\n10^-12 (3.7 x 10^-12) erg cm^-2 s^-1 and 0.027 counts s^-1 T+48h.\n\nThe  UVOT-enhanced position of the afterglow has already been reported\nby Osborne et al. (GCN Circ. 10930).\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00426722.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10935,
  "createdOn": 1278260281000,
  "email": "grupe@astro.psu.edu",
  "subject": "GRB 100704A: Swift XRT refined analysis",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <grupe@astro.psu.edu>",
  "eventId": "GRB 100704A"
}