Universal formulation of quasi-Keplerian motion, and its applications

We derive the universal solution to the Kepler-Coulomb problem with an additional inverse-square potential, valid for any type of orbit, and describe three prominent applications in astrodynamics: the relativistic precession of the apsides, the numerical integration of perturbed Kepler-Coulomb problems with a generalized leapfrog, and the averaged motion of earth-orbiting satellites with the J2 perturbation. The modified orbital elements and Delaunay variables are presented as well.