Space Operations Center (SpOC), formerly Air Force Space Command (AFSPC), approved the public release of the unclassified Simplified General Perturbations #4 (SGP4) propagator. SGP4 is an analytic method based on a general perturbation theory for generating ephemerides for satellites in earth-centered orbits. It is the proper means for correctly propagating a Combined Space Operations Center (CSpOC) Two Line Element (TLE).

The intent of the public release of SGP4 is to ensure all organizations which operate space systems have a propagator compatible with data products produced by CSpOC and to foster interoperability with our partners and allies. Below you will find links to download SGP4 (Windows and Linux, 32 and 64 bit). Users downloading the software must comply with the terms and conditions of the SGP4 license agreement.