{
  "subject": "GRB 100513A: Swift XRT refined analysis",
  "eventId": "GRB 100513A",
  "bibcode": "2010GCN.10754....1M",
  "createdOn": 1273761165000,
  "circularId": 10754,
  "submitter": "Vanessa Mangano at INAF-IASFPA  <vanessa@ifc.inaf.it>",
  "email": "vanessa@ifc.inaf.it",
  "body": "V. Mangano (INAF IASF Pa), B. Sbarufatti (INAF IASF Pa, INAF OAB)\nreport on behalf the Swift XRT team:\n\nWe have analysed the first four orbits of XRT data of GRB 100513A\n(Baumgartner et al. in GCN Circ. 10746),\nconsisting of 154 s exposure in Windowed Timing mode\n(from T+130 s to T+284 s) and 9 ks exposure in Photon Counting\nmode (from T+285 s to T+19 ks).\nThe UVOT-enhanced XRT position was given by Evans et al.\nin GCN Circ. 10751.\n\nAfter an initial flaring activity the light curve can be modelled\nwith a power-law decay with an index of alpha=3.3 +/- 0.15\nfollowed by a break at 714 +/- 40 s to an alpha=0.78 +/- 0.04.\n\nA spectrum formed from the WT[PC] mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.0+/-0.2 [2.3+/-0.2].\nThe best-fitting absorption column at the estimated redshift z=4.8\n(Cenko et al. in GCN Circ. 10752) is 1.9 +/- 1.1 x 10^22 cm^-2,\nin excess of the Galactic value of 4.2 x 10^20 cm^-2 (Kalberla et al. \n2005).\nUncertainties are given at 90% c.l.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from these spectra is 3.4 x 10^-11 (4.3 x 10^-11) erg cm^-2 \ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.78, the count rate at T+24 hours will be 0.004 count s^-1, corresponding\nto an observed (unabsorbed) 0.3-10 keV flux of 1.4 x 10^-13 (1.7 x 10^-13)\nerg cm^2-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00421814.\n\nThis circular is an official product of the Swift-XRT team."
}