  Let SU_X(3) be the moduli space of semi-stable vector bundles of rank 3 and
trivial determinant on a curve X of genus 2. It maps onto P^8 and the map is a
double cover branched over a sextic hypersurface called the Coble sextic. In
the dual P^8 there is a unique cubic hypersurface, the Coble cubic, singular
exactly along the abelian surface of degree 1 line bundles on X. We give a new
proof that these two hypersurfaces are dual. As an immediate corollary, we
derive a Torelli-type result.
