{
  "bibcode": "2010GCN.10622....1P",
  "body": "C. Pagani (U. Leicester), A. P. Beardmore (U. Leicester)�� and F. E.\nMarshall (NASA/GSFC) report on behalf of the Swift-XRT team:\n\nWe have analysed 3.7 ks of XRT data for GRB 100418A (Marshall et al. GCN\nCirc. 10612), from 70 s to 7.3 ks after the BAT trigger. The data\ncomprise 97 s in Windowed Timing (WT) mode (the first 7 s were taken\nwhile Swift was slewing) with the remainder in Photon Counting (PC)\nmode. The enhanced XRT position for this burst was given by Osborne et\nal. (GCN. Circ 10614).\n\nThe light curve can be modelled with an initial power-law decay with an\nindex of alpha=4.23 (+0.17, -0.16), followed by a break at T+474 s to an\nalpha of 0.21 (+0.22, -0.24).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index of 4.29 (+0.33, -0.30). The\nbest-fitting absorption column is 2.1 (+/-0.4) x 10^21 cm^-2, in excess\nof the Galactic value of 4.8 x 10^20 cm^-2 (Kalberla et al. 2005). The\ncounts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 2.0 x 10^-11 (1.3 x 10^-10) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.21, the count rate at T+24 hours will be 0.012 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x\n10^-13 (1.6 x 10^-12) erg cm^-2 s^-1.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00419797.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 10622,
  "createdOn": 1271678700000,
  "email": "cp232@star.le.ac.uk",
  "subject": "GRB 100418A: Swift-XRT Refined Analysis",
  "submitter": "Claudio Pagani at U of Leicester  <cp232@star.le.ac.uk>",
  "eventId": "GRB 100418A"
}