{
  "bibcode": "2010GCN.10691....1G",
  "body": "D. Grupe (PSU) reports on behalf of the Swift-XRT team:\n\nWe have analyzed 14.2 ks of XRT data for GRB 100425A (Grupe et al.\nGCN Circ. 10673), from 85 s to 81 ks after the BAT trigger. The\ndata consist of 106s in Windowed Timing mode (WT) and 14.1 ks\nin  Photon Counting (PC) mode. The current XRT light curve can be\nfit by a broken power law model with an initial decay slope of\n5.3+/-0.3 with a beak at 330+/-20 s followed by a shallow decay\nslope of 0.55+/- 0.05. The last data point at 77 ks after the\nburst suggests a break at about 60ks. However, this is based on\none data point. Therefore, a prediction on the future behavior of\nthe  X-ray afterglow can not be given at this point.\n\n\nA spectrum formed from the WT mode data can be fitted with an\nabsorbed power-law with a photon spectral index of 4.00 (+/-0.15).\nThe best-fitting absorption column density is\n1.49 (+0.18, -0.17) x 10^22 cm^-2, at a redshift of 1.755\n(Goldini et al. GCN Circ 10684), in addition to the Galactic value\nof 8.6 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum\nhas a photon index of 2.30+/-0.13 and a best-fitting\nabsorption column density consistent with the Galactic value.\nBased on this spectrum, the counts to observed (unabsorbed)\n0.3-10 keV flux conversion  factor deduced from this spectrum is\n3.77 x 10^-11 (5.17 x 10^-11) erg cm^-2 count^-1.\n\nSwift will continue observing the X-ray afterglow of GRB 100425A\nover the next few days.\n\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00420398.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10691,
  "createdOn": 1272302773000,
  "email": "grupe@astro.psu.edu",
  "subject": "GRB 100425A: Swift XRT refined analysis",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <grupe@astro.psu.edu>",
  "eventId": "GRB 100425A"
}