{
  "bibcode": "2008GCN..8701....1S",
  "body": "M.C. Stroh and E. A. Hoversten (PSU) report on behalf of the Swift-XRT  \nteam:\n\nWe have analyzed the first seven orbits of XRT data from GRB 081221  \n(Hoversten et al., GCN 8687) beginning 73s after the trigger. The  \nSwift-XRT data consists of 803s in Windowed Timing (WT) mode and 5.9ks  \nin Photon Counting (PC) mode. The enhanced XRT position for this burst  \nwas reported by Evans et al. (GCN Circ. 8690).\n\nThe X-ray light curve begins with count rates near 10^3 cts/s and has  \nan early flare reaching 1130 cts/s at T+103s. Following the flare, the  \nlight curve can be modeled with a double broken power-law with initial  \ndecay rate of 5.48 +/- 0.08, initial break time at T+207s, second  \ndecay rate of 0.68 +/- 0.20, second break time at T+896s, and a final  \ndecay rate of 1.35 +/- 0.04. If the light curve follows the same  \ndecline, we predict count rates at T+24hr and T+48hr to be 1.6e-2 and  \n6.4e-3 respectively.\n\nThe time-averaged WT spectrum can be fit with an absorbed power law  \nwith photon index Gamma = 1.994 (+/-0.014) and nH of 3.24 (+/- 0.05)  \ne21 cm^-2 which is in excess of the Galactic value of 2.03e20 cm^-2  \n(Kalberla et al. 2005). The absorbed (unabsorbed) 0.3-10.0 keV flux is  \n2.44 (3.86) e-9 ergs/cm^2/s.\n\nThe time-averaged PC spectrum can be fit with an absorbed power law  \nwith photon index Gamma = 2.37 (+/-0.15) and nH of 3.5 (+/-0.5) e21  \ncm^-2. The absorbed (unabsorbed) 0.3-10.0 keV flux is 1.04 (2.17) e-11  \nergs/cm^2/s.\n\nThis circular is an official product of the Swift-XRT team.",
  "circularId": 8701,
  "createdOn": 1229955967000,
  "email": "stroh@astroh.org",
  "subject": "GRB 081221: Swift-XRT Refined Analysis",
  "submitter": "Michael Stroh at PSU/Swift  <stroh@astroh.org>",
  "eventId": "GRB 081221"
}