{
  "bibcode": "2003GCN..2076....1B",
  "body": "GRB030328: Full Observation, X-ray Fading and Spectrum Measured with Chandra\n\nN. R. Butler, H. L. Marshall, P. G. Ford, R. K. Vanderspek, G. R.\nRicker (MIT), J. G. Jernigan (U.C. Berkeley), and D. Q. Lamb (U. Chicago)\n\nreport:\n\nWe have analyzed the full 94.0 ksec (livetime) Chandra LETGS \nobservation of GRB030328 (Villasenor et al, GCN1978), lasting from \nMarch 29.112 (t[burst] + 15.33 hr) until March 30.278 (t[burst] + \n43.32 hr).  The mean counting rate for the X-ray afterglow (Butler et \nal. GCN2007) is 0.012 counts/s (summed over the dispersed signal from \nthe LETGS, and including the 0th order flux).  We observe that the \nbrightness over the full observation decays with a slope -1.5 +/- \n0.1, consistent with the value reported by Ford et al. (GCN2027). \n(The chi^2 is 34.27 for 30 degrees of freedom, and the fit is \nrejectable at only 73% confidence.)  We see no evidence for a \ntemporal break.  We fit the dispersed LETGS counts (+/-1 orders \nsummed) and the counts in 0th order jointly by minimizing chi^2, \nrequiring 12 or more counts per spectral bin.  In the 0.5 to 3.0 keV \nband, the data are well fit (chi^2/nu=48.45/48, rejectable at 54% \nconfidence) by an absorbed power-law:\n\ndN/dE = A * E^ (-gamma) * exp(-NH * sigma[E]) ,\n\nwhere NH = ( 5 +/- 3 ) x 10^20 cm^(-2) is the line of sight column \ndensity, which is consistent with the anticipated galactic absorption \nin the source direction; A = ( 6.8 +/- 0.9 ) x 10^(-5) ph cm^(-2) \ns^(-1) keV^(-1); and gamma = 1.7 +/- 0.2 .  These are 1 parameter \n1-sigma confidence intervals.\n\nIntegrating the above model over the 0.5 to 3.0 keV band, the mean \nflux for the duration of the Chandra observation is ~1.9 x 10^(-13) \nergs cm^(-2) s^(-1).\n\nOur analyses are continuing, and more detailed results will be posted at:\n\nhttp://space.mit.edu/HETE/\n\nWe thank Harvey Tananbaum for his generous allocation of Director's \nDiscretion Time to this observation, and the Chandra X-ray \nObservatory Operations personnel for the impressive promptness with \nwhich this observation was planned and carried out.\n\nThe preliminary results reported here may be cited.",
  "circularId": 2076,
  "createdOn": 1049329376000,
  "email": "grr@space.mit.edu",
  "subject": "GRB030328: Full Observation, X-ray Fading and Spectrum Measured",
  "submitter": "George Ricker at MIT  <grr@space.mit.edu>",
  "eventId": "GRB 030328"
}