{
  "bibcode": "2005GCN..3915....1R",
  "body": "D. Reichart reports on behalf of the UNC team of the FUN GRB Collaboration.\n\nWe have computed preliminary error bars on the temporal and spectral\nindexes of Haislip et al. (GCN 3914).  The temporal index is -1.20 +/- 0.17\nand the spectral index is -0.35 +/- 0.33.  This disfavors the ISM-RED and\nWIND-RED cases at the 2.2 sigma confidence level, the ISM-BLUE case at the\n1.3 sigma confidence level, and the WIND-BLUE case only at the 0.3 sigma\nconfidence level (e.g., Sari, Piran & Narayan 1998; Chevalier & Li 2000).\nIf the WIND-BLUE case is borne out by further observations, this suggests\nan electron-energy distribution index of p = 1.9 +/- 0.2, as well as a\nmassive-star origin.\n\nIf the NIR afterglow is strongly extinguished, and the intrinsic spectrum\nis even shallower than -0.35, or even positive, then none of the standard\ncases hold.  This also suggests that the afterglow is probably not strongly\nextinguished, and supports the conclusion of Haislip et al. (GCN 3914) that\nthe sharp spectral break between the J and i bands is likely due to\ndropout.\n\nFurthermore, given that the K to J spectral index is so shallow, and the J\nto i spectral index is so steep, the redshift range is probably narrower\nthan that implied by the J and i filter centers (5.3 < z < 9.0), and is\nprobably between 6 and 8.  Careful modeling will better constrain this, but\nz, Z and/or Y observations, preferably contemporaneous with addition NIR\nobservations would be most useful.",
  "circularId": 3915,
  "createdOn": 1125844567000,
  "email": "reichart@physics.unc.edu",
  "subject": "GRB 050904: Environmental Constraints",
  "submitter": "Daniel E. Reichart at U.North Carolina  <reichart@physics.unc.edu>",
  "eventId": "GRB 050904"
}