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  2. American Ephemeris and Nautical Almanac - Wikipedia

    en.wikipedia.org/wiki/American_Ephemeris_and...

    The American Ephemeris and Nautical Almanac was published for the years 1855 to 1980, containing information necessary for astronomers, surveyors, and navigators. It was based on the original British publication, The Nautical Almanac and Astronomical Ephemeris, with which it merged to form The Astronomical Almanac, published from the year 1981 to the present.

  3. Astronomical Almanac - Wikipedia

    en.wikipedia.org/wiki/Astronomical_Almanac

    The Astronomical Almanac [1] is an almanac published by the United Kingdom Hydrographic Office; it also includes data supplied by many scientists from around the world.On page vii, the listed major contributors to its various Sections are: H.M Nautical Almanac Office, United Kingdom Hydrographic Office; the Nautical Almanac Office, United States Naval Observatory; the Jet Propulsion Laboratory ...

  4. Earth-centered, Earth-fixed coordinate system - Wikipedia

    en.wikipedia.org/wiki/Earth-centered,_Earth...

    The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.

  5. Time to first fix - Wikipedia

    en.wikipedia.org/wiki/Time_to_first_fix

    Many receivers can use as many as twelve channels simultaneously, allowing quicker fixes (especially in a cold case for the almanac download). [1] Many cell phones reduce the time to first fix by using assisted GPS (A-GPS): they acquire almanac and ephemeris data over a fast network connection from the cell-phone operator rather than over the ...

  6. Ephemeris - Wikipedia

    en.wikipedia.org/wiki/Ephemeris

    In astronomy and celestial navigation, an ephemeris (/ ɪ ˈ f ɛ m ər ɪ s /; pl. ephemerides / ˌ ɛ f ə ˈ m ɛr ɪ ˌ d iː z /; from Latin ephemeris 'diary', from Ancient Greek ἐφημερίς (ephēmerís) 'diary, journal') [1] [2] [3] is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position ...

  7. Minor Planet Center - Wikipedia

    en.wikipedia.org/wiki/Minor_Planet_Center

    The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to astrometric data, the MPC

  8. The Nautical Almanac - Wikipedia

    en.wikipedia.org/wiki/The_Nautical_Almanac

    Two sample pages of the 2002 Nautical Almanac. The Nautical Almanac has been the familiar name for a series of official British almanacs published under various titles since the first issue of The Nautical Almanac and Astronomical Ephemeris, for 1767: [1] this was the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea.

  9. JPL Horizons On-Line Ephemeris System - Wikipedia

    en.wikipedia.org/wiki/JPL_Horizons_On-Line...

    JPL Horizons On-Line Ephemeris System provides access to key Solar System data and flexible production of highly accurate ephemerides for Solar System objects. Osculating elements at a given epoch (such as produced by the JPL Small-Body Database ) are always an approximation to an object's orbit (i.e. an unperturbed conic orbit or a " two-body ...