{
  "bibcode": "2010GCN.11144....1M",
  "body": "V. Mangano (INAF IASF-PA) and B. Sbarufatti (INAF OAB/INAF IASF-PA)\nreport on behalf of the Swift-XRT team:\n\nWe have analyzed 8.7 ks of XRT data for GRB 100823A (Mangano  et al. GCN\nCirc. 11135), from 59 s to 22 ks after the  BAT trigger. The data\ncomprise 68 s in Windowed Timing (WT) mode (the first 8 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC) mode.\nThe light curve can be modeled with a broken power-law decay with an\ninitial decay index of alpha1=2.9 (+/-0.2) , a break at T+163 (+/-11) s\nand a final decay index of alpha2=1.19 (+/-0.03).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index    of 3.6 (+0.8, -0.6). The\nbest-fitting absorption column is  2.8 (+1.2, -0.9) x 10^21 cm^-2,\nin excess of the Galactic value of 3.7 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum (extracted from T+137.5 s to T+22.3 ks, 8.65 ks\nexposure) has a photon index of 2.2 (+0.3, -0.2) and a best-fitting \nabsorption\ncolumn of 2.1 (+0.6, -0.5) x 10^21 cm^-2. The counts to observed \n(unabsorbed)\n0.3-10 keV flux conversion factor deduced from this spectrum is\n4.0 x 10^-11 (6.6 x 10^-11) erg cm^-2 count^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.87, the count rate at T+48 hours will be 9.0 x 10^-4 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of\n3.6 x 10-14 (5.9 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/00432420.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 11144,
  "createdOn": 1282658394000,
  "email": "vanessa@ifc.inaf.it",
  "subject": "GRB 100823A: Swift XRT refined analysis",
  "submitter": "Vanessa Mangano at INAF-IASFPA  <vanessa@ifc.inaf.it>",
  "eventId": "GRB 100823A"
}