{
  "bibcode": "2009GCN..9449....1S",
  "body": "Sbarufatti B., Mangano V. (INAF-IASFPA) and T. Sakamoto (NASA/UMBC)\nreport on behalf of the Swift Team:\n\nWe have analyzed the first eleven orbits of Swift-XRT data of\nGRB 090529 (trigger 353540; Sakamoto, et al., GCN Circ. 9430),\ncomprising 148 s taken in Windowed Timing (WT) mode, from T+203 s\nto T+352 s, and 8.2 ks in Photon Counting (PC)\nmode from T+353 s to T+46.7 ks.\n\nThe best position for the X-ray afterglow is the XRT UVOT-enhanced\nposition:RA, Dec = 212.46850, +24.45919 which is equivalent\nto:\n\nRA (J2000): 14h 09m 52.44s\nDec (J2000): +24d 27' 33.1\"\n\nwith an uncertainty of 1.8 arcsec (radius, 90% confidence), as given\nby Osborne, et al., GCN Circ 9433.\n\nThe 0.3-10 keV X-ray light curve is best fitted by a broken power-law\nwit early  decay index -3.5+/-0.1, late decay index -0.7+/-0.2 and the\nbreak at (1100+180-140) s after the trigger. Faint flaring activity is\ndetected along the decay. If decaying at the present rate, the\npredicted rate for T+ 48h is 2.8e-3 counts/s. However, we remark that\na second break followed by a steepening of the light-curve is\nexpected. The issue will be clarified when new data from the Swift\nobservations (resumed today at 14:35 UT) will be available.\n\nThe average spectrum of the steep decay part of the afterglow (WT + PC\nfrom T+203s to T+1.1 ks) is best fit by a power-law with indices\n2.5+/-0.12 for the WT data and 2.2+/-0.15 for the PC data. The\nabsorbing column is NH = (2.3-1.5+1.7)E20 cm^-2 slightly in excess\nwith respect to the Galactic value of 1.61E20 cm^-2 (Kalberla et\nal. 2005). The average observed (unabsorbed) fluxes are\n4.5(5.1)E-10 ergs cm^-2 s^-1 for the WT data and 1.5(1.6)E-11 for the\nPC data.\nThe average spectrum of the flat decay part of the afterglow,\nconsisting of 7.5 ks of PC data, observed from T+1.1 ks to T+46.7 ks\n(containing 120 photons) was fitted using Cash statistics with an\nabsorbed power-law model. The absorbing column NH is (9 -7 +9)E20\ncm^-2, consistent with the Galactic value, the photon index is\n2.3+/-0.5. The observed (unabsorbed) flux is 5.3(7.2)E-13 ergs cm^-2\ns^-1. The C-statistic is 66.4 with 101 bins.\nThe count-rate to flux conversion factor is 4.7E-11.\nAll quoted errors are at 90% confidence level.\n\nThe results of the XRT-team automatic analysis are available at\nhttp://www.swift.ac.uk/xrt_products/00353540.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 9449,
  "createdOn": 1243702082000,
  "email": "sbarufatti@ifc.inaf.it",
  "subject": "GRB 090529: Swift-XRT refined analysis",
  "submitter": "Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti@ifc.inaf.it>",
  "eventId": "GRB 090529"
}