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    Re: Using Polaris and the Sunrise or Sunset to determine Lat/Long with the "time sight"
    From: Andrés Ruiz
    Date: 2010 Nov 25, 08:54 +0100

    Recently I have written the “Time section” in Wikipedia, see Longitude by chronometer at http://en.wikipedia.org/wiki/Longitude_by_chronometer, also you have a chart flow for the calculation.

     

    For past methods, using tables or other pre-formatted formulae, you can consult Chauvenet, or old Bowditch, available for free at google books.

     

    Regards

    --

    Andrés Ruiz

    Navigational Algorithms

    http://sites.google.com/site/navigationalalgorithms/

     


    De: navlist-bounce@fer3.com [mailto:navlist-bounce@fer3.com] En nombre de Doug MacPherson
    Enviado el: jueves, 25 de noviembre de 2010 8:12
    Para: NavList@fer3.com
    Asunto: [NavList] Using Polaris and the Sunrise or Sunset to determine Lat/Long with the "time sight"

     

    Chuck: thanks for the great clarification. I like to play around with the time sight method.

    Recently I have been getting latitude from polaris, and then using the exact time the sun rises or sets (no sextant required)to get the altitude of the sun for the "time sight" and subsequently the longitude. Although the sun is not at the exact PVC crossing, it is (for my latitude of 38 degrees) close to bearing due East or West.

    I have a copy of the 1938 Bowditch and use the time sight method described in Chapter XII.

    This seems to provide latitude and longitude with a minimum of calculation and work. Was this method ever used in the past?

    Any thoughts?

    Doug MacPherson

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