JPL Horizons On-Line Ephemeris System
JPL Horizons On-Line Ephemeris System provides easy access to key Solar System data and flexible production of highly accurate ephemerides for Solar System objects.
Osculating elements at a given epoch are always an approximation to an object's orbit. The real orbit considers perturbations by all planets, a few of the larger asteroids, a few other usually small physical forces, and requires numerical integration.
Jet Propulsion Laboratory ephemerides do not use things such as periods, eccentricities, etc. Instead, JPL integrates the equations of motion in Cartesian coordinates, and adjusts the initial conditions in order to fit modern, highly accurate measurements of planetary positions.
As of August 2015, Horizons now uses ephemeris DE431.There are 3 ways to use the system and all of them can be automated:
The Horizons system was intended to be easy to use and should have a step-function learning curve.
