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    A "three dimensional slide-rule" for celestial
    From: Ed Popko
    Date: 2016 Feb 2, 05:59 -0800

    Now here is an interesting navigation slide rule - and 3D too...     The Astra-Plot a "three dimensional slide-rule" for celestial navigation, 1969

    According to the writeup:

    Five specific data to specify the location of a ship

    The device specifies the location of a ship to within one nautical mile without the need of any paper calculations. Five specific data are required: First, the approximate position of the ship as determined by the compass bearing and travel time; second, the height of a star above the horizon, preferably the sun, as measured by a sextant; third, the exact compass direction of that star as determined by an amplitude compass; fourth, its hour angle as determined by the time of day and a nautical chart and, fifth, the angular distance of the star to the celestial equator as determined by the nautical chart or the star map.


    Ed Popko


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