{
  "bibcode": "2009GCN..9378....1R",
  "body": "B. A. Rowlinson and P. Evans (U Leicester) report on behalf of the\nSwift-XRT team:\n\nWe have analysed 3.0 ks of XRT data for GRB 090516 (Rowlinson et al. GCN\nCirc. 9374), from 170 s to 6.4 ks after the BAT trigger. The data\ncomprise 327 s in Windowed Timing (WT) mode with the remainder in Photon\nCounting (PC) mode. The enhanced XRT position for this burst was given\nby Beardmore et al. (GCN. Circ 9376).\n\nThe light curve can be modelled with a power-law decay with two flares\nsuperimposed on it. The initial decay index is alpha=3.27 (+0.11,\n-0.10). At T+601 (+138, -52) s the decay flattens to an alpha of 0.93\n(+0.11, -0.10).\n\nA spectrum formed from the WT mode data can be fitted with an absorbed\npower-law with a photon spectral index of 2.09 (+/-0.04). The\nbest-fitting absorption column is 1.57 (+0.10, -0.09) x 10^21 cm^-2, in\nexcess of the Galactic value of 4.5 x 10^20 cm^-2 (Kalberla et al.\n2005). The PC mode spectrum has a photon index of 2.09 (+0.13, -0.12)\nand a best-fitting absorption column of 9.6 (+2.6, -2.5) x 10^20 cm^-2.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 3.6 x 10^-11 (4.8 x 10^-11) erg cm^-2\ncount^-1.\n\nIf the light curve continues to decay with a power-law decay index of\n0.93, the count rate at T+24 hours will be 0.03 count s^-1,\ncorresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x\n10^-12 (1.4 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/00352190.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9378,
  "createdOn": 1242504241000,
  "email": "bar7@star.le.ac.uk",
  "subject": "GRB 090516: Swift XRT refined analysis",
  "submitter": "Antonia Rowlinson at U.of Leicester  <bar7@star.le.ac.uk>",
  "eventId": "GRB 090516"
}