On a first integral of the Kepler problem

A quadratic first integral of the Kepler problem, obtained by Benenti (''Orthogonal separable dynamical systems,'' 5th International Conference on Differential Geometry and its Applications, 24-28 August 1992, Silesian University at Opava) through separation in elliptic coordinates, is shown to be intimately connected with the pre-quantization of the Kepler manifold, thus acquiring a physical interpretation. (C) 1997 American Institute of Physics.