Data Sources

For

JPL's IGS site for GPS data and ephemerides.

USAF Col. T.S. Kelso's Celestrak site for NORAD elements and documentation.

US Coast Guard Navigation Center's Navcen site for NANU messages, current GPS status, and a variety of other information.

IERS for earth orientation parameters. Get "finals.all" for post-processing applications.

NOAA is the place for F10, Ap, ap, & Kp data.

WGS-84 from NIMA.

MSIS/MSISE atmosphere models.

Ionosphere data from JPL.

CDDIS Tracking Data for GPS, GLONASS, SLR, VLBI, DORIS.