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    Re: A "three dimensional slide-rule" for celestial
    From: Brad Morris
    Date: 2016 Feb 2, 18:45 -0500

    The article states that the price was 30,000 marks just when GPS took over.  Call that 1973.  The exchange rate was 3.2 DM/$1 in 1973, yielding 9375USD.  Account for inflation, and this device should sell  for over $58,000 today.

    The claim of 1' without electrons is impressive, yet my high end programmable electronic calculator in 1975 was ~$400, including the printer.  Roughly 1/20th the price and the calculation was accurate to several decimal places, far exceeding the claimed device accuracy.

    I would like to understand how this device functions!


    On Feb 2, 2016 3:14 PM, "Ed Popko" <NoReply_EdPopko@fer3.com> wrote:

    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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