{
  "bibcode": "2009GCN..8847....1G",
  "body": "D. Grupe (PSU) reports on behalf of the Swift-XRT team:\n\nWe have analyzed 7.7 ks of XRT data for GRB090123 (Grupe et al. GCN \nCirc. 8842),\nbeginning 106 s after the BAT trigger. The data comprise 334 s in Windowed\nTiming (WT) mode with the remainder in Photon Counting (PC) mode.\nThe enhanced XRT position for this burst was given by Osborne et al.\n(GCN. Circ 8843).\n\nThe light curve can be modeled with an initial power-law decay with an\nindex of alpha=1.78 (+0.06, -0.08), followed by a break at T+1530 \n(+720,-220) s to\nan alpha of 1.20 (+0.08, -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 1.65+/-0.05 with an absorption \ncolumn fixed to the Galactic\nvalue of 1.79 x 1020 cm-2 (Kalberla et al. 2005). The PC mode spectrum \nhas a\nphoton index of 1.81+/-0.08 and an absorption column density also \nconsistent\nwith the Galactic value.\nThe counts to observed (unabsorbed) 0.3-10 keV flux conversion factor\ndeduced from this spectrum is 4.2 x 10-11 (4.5 x 10-11) erg cm-2 count-1.\n\n\nIf the light curve continues to decay with a power-law decay index of 1.20,\nthe count rate at T+24 hours will be 0.0031 counts/s, corresponding to an\nobserved (unabsorbed) 0.3-10 keV flux of 1.3 x 10-13 (1.4 x 10-13) erg cm-2\ns-1.",
  "circularId": 8847,
  "createdOn": 1232738496000,
  "email": "grupe@astro.psu.edu",
  "subject": "GRB 090123: Swift XRT refined analysis",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <grupe@astro.psu.edu>",
  "eventId": "GRB 090123"
}