{
  "bibcode": "2009GCN..9208....1P",
  "body": "M. Perri and G. Stratta (ASDC) report on behalf of the Swift-XRT Team:\n\nWe have analysed the first 31 ks of Swift-XRT data obtained from\nGRB 090422 (trigger 349931; Ukwatta et al., GCN Circ. 9185), starting\nfrom T+70 s and ending at T+70 ks.\n\nThe best position of the X-ray afterglow is the UVOT-enhanced XRT\nposition given in Beardmore et al. (GCN Circ. 9194).\n\nThe 0.3-10 keV X-ray light curve is well described by a double broken\npower-law model with decay indices alpha1=-1.7+/-0.2, alpha2=-0.2+/-0.3,\nalpha3=-1.0+/-0.1 and temporal breaks t1=421+/-92 s and t2=1.5+/-0.3 ks .\n\nThe X-ray spectrum is well fit by an absorbed power-law model with a\nphoton index of 2.5+/-0.2 and a column density of (2.3+/-0.7)e21 cm**-2\nin excess to the Galactic one in the direction of the source\n(1.7e21 cm**-2, Kalberla et al. 2005). The count-rate to observed\n(unabsorbed) 0.3-10 keV flux conversion factor deduced from this\nspectrum is 3.6(8.7)E-11 erg cm**-2 count**-1.\n\nAssuming the X-ray emission continues to decline at the same rate, we\npredict a 0.3-10 keV XRT count rate of 2e-3 count/s at T+48hr, which\ncorresponds to an observed 0.3-10 keV flux of ~7e-14 erg/cm**2/s.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00349931.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9208,
  "createdOn": 1240498723000,
  "email": "perri@asdc.asi.it",
  "subject": "GRB 090422: Swift-XRT refined analysis",
  "submitter": "Matteo Perri at ISAC/ASDC  <perri@asdc.asi.it>",
  "eventId": "GRB 090422"
}