{
  "bibcode": "2010GCN.10987....1S",
  "body": "B. Sbarufatti (INAF OAB/INAF IASF-PA) , V. Mangano (INAF/IASF_PA)\nand C. B. Markwardt (CRESST/GSFC/UMD) report on behalf of the\nSwift-XRT team:\n\nWe have analysed 4.3 ks of XRT data for GRB 100725A (Markwardt\tet al.\nGCN Circ. 10979), from 82 s to 11.0 ks after the  BAT trigger. The data\ncomprise 177 s in Windowed Timing (WT) mode with the remainder in\nPhoton Counting (PC) mode. The light curve can be modelled with an\ninitial power-law decay with an index of alpha=1.1 (+/-0.1), followed\nby a break at T+270 s to an alpha of 6.5 (+/-0.5). After a second break\nat T+590 s the decay follows an index of alpha=0.9 (+0.3 -0.4).\n\nThe spectrum formed from the WT mode data can be fitted with an\nabsorbed power-law with a photon spectral index of 1.18 (+/-0.08).\nThe best-fitting absorption column is  1.2 (+/-0.3) x 10^21 cm^-2,\nin excess of the Galactic value of 4.6 x 10^20 cm^-2 (Kalberla et al.\n2005). The spectrum formed from the PC mode data can be fitted with\nan absorbed power-law with a photon spectral index of 1.20 (+/-0.09).\nThe best-fitting absorption column is 8.9 (+10.0 -0.8) x 10^20 cm^-2,\nmarginally in excess of the Galactic value. The counts to observed\n(unabsorbed) 0.3-10 keV flux conversion factor is 6.2 x 10^-11\n(6.7 x 10^-11) ergcm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.9, the count rate at T+24 hours will be 2.4 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.4 x\n10^-14 (1.6 x 10^-14) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00429954.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10987,
  "createdOn": 1280070121000,
  "email": "boris.sbarufatti@brera.inaf.it",
  "subject": "GRB 100725A: Swift XRT refined analysis",
  "submitter": "Boris Sbarufatti at INAF-OAB/IASFPA  <boris.sbarufatti@brera.inaf.it>",
  "eventId": "GRB 100725A"
}