3 Re - Analysis of Polarization in the γ - ray flux of GRB 021206

A previous analysis of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI ) observation of GRB 021206 found that the gamma-ray flux was 80±20% polarized. We have re-examined this data, and we detect no signal which can be interpreted as due to polarization for GRB 021206. First, we find the number of scattering events capable of measuring polarization, due to a photon scattered from one detector to another with a count produced in both, is considerably lower than previously estimated, by a factor of ≈10 (830±150, vs. 9840±96). Nonetheless, we develop a polarization detection analysis limited in sensitivity only by Poisson noise, and which does not require a space-craft mass model to produce the simulated un-polarized lightcurve as in the previous analysis. We find no signal which might be interpreted as due to polarization in GRB 021206. The non-detection of a polarization signal is at variance with the previous analysis of Coburn and Boggs (2003). While we do not determine the cause of this discrepancy, we suggest it may be due to uncertainties related to using the mass model to estimate the zero-polarization (“null”) lightcurve. We also describe how a particular filtering of the data produces a signal which might be interpreted as due to polarization, but is actually due to detector-related effects.