Jet Propulsion Laboratory Development Ephemeris

The Jet Propulsion Laboratory Developmental Ephemeris (JPL DE) is a product producted by the Jet Propulsion Laboratory in Pasadena, California. It is a system of numerical coefficients (for Tschebyshev polynomials) which can be used to calculate the positions of the major and some minor planets of the solar system both in the past and the future. The positions given represent the best fit between positions of planets measured by radio signals from spacecraft, astronomical observations of planets and small bodies in the solar system, and ancient observations of eclipses, among others.

There are several different versions of the JPL DE, each one with a 3-digit serial number following. They differ according to the year the data was revised and released, and according to the accuracy and time-range that each JPL DE covers.