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Compressed Ephemeris Data


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1968-11-08 to 1972-04-16


This data set which contains complete trajectory information was generated at NSSDC by taking the most accurate information from each ephemeris tape and eliminating overlap. The data set consists of one IBM 7094, binary magnetic tape. Each logical record contains 89 words, and each physical record contains 20 logical records. The following information is available in intervals of 1 day (except for periods when the spacecraft is close to the earth, when the interval may be shorter) -- (1) date, (2) time, (3) distance from the earth to the probe, (4) distance from the earth to the sun, (5) distance from the earth to the moon, (6) distance from the sun to the probe, (7) geocentric right ascension and declination of probe, sun, moon, (8) geocentric latitude, longitude, and altitude above the earth, (9) earth-sun-probe angle, (10) earth-probe-sun angle, (11) sun-probe-near limb of earth angle (sun-probe-earth angle minus the angular semi-diameter of earth where the angular semi-diameter would be the probe-centered angle between earth limb and center of earth), (12) moon-earth-probe angle, (13) moon-probe-sun angle, (14) earth-probe-moon angle, (15) Canopus-probe-earth angle, (16) Canopus-probe-sun angle, (17) angle made by the sun to probe vector and the ecliptic plane of date, (18) X, Y, Z components of spacecraft in the sun-earth line coordinate system (sun-centered system, X axis is along the sun-to-earth vector, Z axis is toward ecliptic north pole), (19) longitude of spacecraft in the sun-earth line coordinate system, (20) X, Y, Z components of spacecraft in geocentric, selenocentric, heliocentric Venus-centered, Mars-centered, Saturn-centered, and Jupiter-centered inertial coordinate (X points to vernal equinox, Z points along the north pole vector with the reference plane being the earth's true equator of date), (21) magnitude of the velocity vector and X, Y, Z components of the velocity vector in geocentric inertial coordinates, (22) geocentric inertial path angle (angle made by probe velocity vector and plane normal to earth-to-probe vector), (23) geocentric inertial azimuth angle (angle between the plane defined by the earth-to-probe vector and the geocentric inertial velocity vector), (24) heliocentric inertial velocity, (25) heliocentric inertial path angle (angle made by the heliocentric velocity vector and the plane normal to the sun-to-probe vector), (26) celestial longitude of probe (angular distance measured counterclockwise along the ecliptic plane of date from the vernal equinox to the projection of the sun-probe vector on a plane as viewed from the ecliptic north pole), (27) celestial longitude of earth, (28) celestial latitude of earth, and (29) various clock angles and hinge and swivel angles which are described in the documentation.

Alternate Names


    • Ancillary: Ephemeris/Orbit/Attitude


    • 68-100A-00E

    Additional Information


    Questions and comments about this data collection can be directed to: Coordinated Request and User Support Office



    NameRoleOriginal AffiliationE-mail

    Selected References

    • Holdridge, D. B., Space trajectories program for the IBM 7094 computer, JPL, Calif. Inst. Technol., TR 32-233, Pasadena, CA, Mar. 1962.
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