{
  "bibcode": "2006GCN..5515....1G",
  "body": "D. Grupe (PSU) reports on behalf of the Swift/XRT team\n\n\n\nWe have analyzed the first  orbit with a total observing time\nof 2.06 ks of Swift XRT data of GRB 060904A (Grupe et al., GCN 5502).\n\nThe X-ray light curve displays the end of a giant flare with a\nflattening of the light curve at 200s after the burst. The initial\ndecay slope is 3.8+/-0.2 followed by 1.3+/-0.2.\n\nSpectral fits to the Windowed Timing mode data during the flare phase\nsuggest a significant absorption column density in excess of the\nGalactic value (1.41e20 cm**-2). The spectrum can be fitted by a\nsingle power law with a photon index Gamma=1.93+/-0.04 and an\nabsorption column density NH=1.7+/-0.1e21.\n\nDue to the detection of GRB 060904B (Grupe et al., GCN 5505) about\nabout 1.5 hours after the trigger of GRB 060904A, only one orbit has\nbeen observed on GRB 060904A and the data were only taken in Windowed\nTiming mode. Therefore no photon counting  mode data exist currently\nand no improved position can be given yet.\n\n\n\nThis circular is an official product of the Swift XRT Team.",
  "circularId": 5515,
  "createdOn": 1157367028000,
  "email": "grupe@astro.psu.edu",
  "subject": "GRB 060904A: Swift-XRT refined analysis",
  "submitter": "Dirk Grupe at PSU/Swift-XRT  <grupe@astro.psu.edu>",
  "eventId": "GRB 060904A"
}