  Let G be a connected reductive group over an algebraically closed field K of
characteristic 0, X an affine symplectic variety equipped with a Hamiltonian
action of G. Further, let * be a G-invariant Fedosov star-product on X such
that the Hamiltonian action is quantized. We establish an isomorphism between
the center of the associative algebra K[X][[h]]^G and the algebra of formal
power series with coefficients in the Poisson center of K[X]^G.
