{
  "bibcode": "2010GCN.10975....1M",
  "body": "V. Mangano (INAF IASF-PA), B. Sbarufatti (INAF OAB/INAF IASF-PA) and\nC. B. Markwardt (CRESST/GSFC/UMD) report on behalf of the Swift-XRT team:\n\nWe have analysed 10 ks of XRT data for GRB 100724A (Markwardt  et al.\nGCN Circ. 10968), from 96 s to 25.1 ks after the BAT trigger. The data\nare entirely in Photon Counting (PC) mode. The light curve can be\nmodelled with  a broken power-law decay with an initial decay index of\nalpha1=0.3 (+/-0.1) , a break at T+525 (+/-90) s and a final decay index of\nalpha2=1.07 (+/-0.03).\n\nA spectrum formed from the PC mode data can be fitted with an absorbed\npower-law with a photon spectral index of 1.98 (+0.20, -0.19).\nThe best-fitting absorption column is consistent with the Galactic value\nof 3.4 x 10^20 cm-2 (Kalberla et al. 2005).  The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum  is 4.8 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n1.1, the count rate at T+24 hours will be 2.4e-3 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of\n1.1 x 10^-13 (1.3 x 10^-13) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00429868.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10975,
  "createdOn": 1279996349000,
  "email": "boris.sbarufatti@brera.inaf.it",
  "subject": "GRB 100724A: Swift XRT refined analysis",
  "submitter": "Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>",
  "eventId": "GRB 100724A"
}