  The elliptic restricted three body problem has been well studied. However,
the previous formulations of the problem have used a rotating coordinate system
to keep the positions of the primary and secondary on the x-axis. This requires
the rotation rate of the rotating coordinate system to speed up and slow down.
The approach here uses a rotating coordinate system with constant rotation
rate. This formulation allows one to conveniently compare solutions of the
elliptic problem with solutions of the circular restricted three body problem.
