In this paper we regularize the Kepler problem on $S^3$ in several
different ways. First, we perform a Moser-type regularization. Then, we
adapt the Ligon-Schaaf regularization to our problem. Finally, we show
that the Moser regularization and the Ligon-Schaaf map we obtained can be
understood as the composition of the corresponding maps for the Kepler problem
in Euclidean space and the gnomonic transformation.
Kepler problem on the sphere, Ligon-Shaaf regularization, geodesic flow on the sphere
70Fxx - Dynamics of a system of particles, including celestial mechanics