  We show that the natural S^1-bundle over a projective special Kaehler
manifold carries the geometry of a proper affine hypersphere endowed with a
Sasakian structure. The construction generalizes the geometry of the
Hopf-fibration $\Sr^{2n+1} \longrightarrow \CP^n$ in the context of projective
special Kaehler manifolds. As an application we have that a natural circle
bundle over the Kuranishi moduli space of a Calabi-Yau threefold is a
Lorentzian proper affine hypersphere.
