{
  "bibcode": "2005GCN..3128....1D",
  "body": "GRB 050315: Variability Analysis of Swift BAT Time History\n\nT. Q. Donaghy, T. Sakamoto, D. Q. Lamb, E. E. Fenimore, D. E. Reichart, \non behalf of the Swift BAT Team report:\n\nWe have calculated the variability measure V (Fenimore and Ramirez-Ruiz\n2000; Reichart et al. 2001) for GRB 050315 (Parsons et al., GCN Circular\n3094), using the Swift BAT time history data for this burst.  We find\nvalues V = 0.017 +/- 0.027, 0.068 +/- 0.022, 0.086 +/- 0.041, and 0.064\n+/- 0.016 (68 percent confidence regions) in the 15-25 keV, 25-50 keV,\n50-100 keV, and 25-100 keV energy bands, respectively.  These values of\nV are the same within the statistical uncertainties; this is consistent\nwith the results of Reichart et al. (2001), who found no significant\ntrend of V with energy for BATSE bursts.\n\nAnalyzing the Swift BAT spectral data for GRB 050315, we find a peak \nphoton energy flux in 1 s of (9.2 +/- 0.6) x 10-8 erg cm-2 s-1 (68%\nconfidence region) in the 33.9 - 339.1 keV energy band [which\ncorresponds to the 100-1000 keV energy band in the rest frame of the\nsource for a redshift of z = 1.949 (Kelson and Berger, GCN Circular\n3101)].  This peak photon energy flux corresponds to an isotropic-\nequivalent peak luminosity in the 100-1000 keV energy band in the rest\nframe of the source of L_obs = (3.2 +/- 0.2) x 10^51 erg s-1.\n\nUsing V in the 25-100 keV energy band as a luminosity (and therefore a\nredshift) estimator, we estimate an isotropic-equivalent luminosity in\n100-1000 keV in the rest frame of the source of log L_V (erg s-1) =\n51.46 +/- 0.747 and a redshift z_V = 1.94 (+2.02/-0.97) for the burst.\nThese values are consistent with the observed values log L_obs (erg s-1) \n= 51.51 (+0.02/-0.04) (90% confidence region) and z = 1.949 (Kelson and \nBerger, GCN Circular 3101).\n\nThese results are encouraging.  They suggest that analyses of the Swift\nBAT time history data for a large sample of bursts will provide a\ndecisive test of the validity of the variability measure V as a\nluminosity (and therefore a redshift) estimator, and if the analyses\nconfirm its validity, they will make possible a better calibration of\nthe estimator.",
  "circularId": 3128,
  "createdOn": 1111363098000,
  "email": "lamb@oddjob.uchicago.edu",
  "subject": "GRB 050315: Variability Analysis of Swift BAT Time History",
  "submitter": "Don Lamb at U.Chicago  <lamb@oddjob.uchicago.edu>",
  "eventId": "GRB 050315"
}