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    Re: A "three dimensional slide-rule" for celestial
    From: Francis Upchurch
    Date: 2016 Feb 3, 06:12 -0000

    Very interesting!

    I would love to know more about how it works . However, I must not try to make a replica! Far too precision engineered for my limited skills. My cylindrical slide rules good for 1-2’ and take 2 mins to get Hc, but then have to plot it to get actual position.

    Francis

     

    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Ed Popko
    Sent: 02 February 2016 20:15
    To: francisupchurch@gmail.com
    Subject: [NavList] A "three dimensional slide-rule" for celestial

     

    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.

    http://www.sdtb.de/January.2290.0.html

    Ed Popko



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