Measuring the polarization of the prompt \gamma -ray emission from GRBs can significantly improve our understanding of both the GRB emission mechanisms , as well as the underlying engine driving the explosion .
We searched for polarization in the prompt \gamma -ray emission of GRB 041219a with the SPI instrument on INTEGRAL .
Using multiple-detector coincidence events in the 100–350 keV energy band , our analysis yields a polarization fraction from this GRB of 98 \pm 33 % .
Statistically , we can not claim a polarization detection from this source .
Moreover , different event selection criteria lead to even less significant polarization fractions , e.g .
lower polarization fractions are obtained when higher energies are included in the analysis .
We can not strongly rule out the possibility that the measured modulation is dominated by instrumental systematics .
Therefore , SPI observations of GRB 041219a do not significantly constrain GRB models .
However , this measurement demonstrates the capability of SPI to measure polarization , and the techniques developed for this analysis .