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    Re: Compare Methods: Lat/Lon Near Noon
    From: Frank Reed
    Date: 2021 Sep 13, 03:55 -0700

    Antoine, you asked:
    "is this Book title not  Latitude and Longitude by the Noon Sight ?
    From here I have identified one such Book - a "ring-bound" copy as you recommend it to be"

    That's the book. Since I originally mentioned Hewitt Schlereth's book in this thread, I feel I should explain what it is and what it is not.

    WHAT IT IS: Hewitt's book is an introductory celestial navigation manual detailing how beginners can get latitude and longitude using sights at and near noon. This is quite similar to the case that I proposed here recently (the example set up for May 22, 2022, originally outlined in this post two weeks ago, in case anyone wants to go back to the basic setup). Only basic sextant skills are required. Almost no math is required. Hewitt spells out the method and provides a basic method for the critical correction for vessel motion which can shift the longitude substantially. The book is a streamlined and well-written practical account of this technique. It also included some almanac data which, of course, has long since expired.

    WHAT IT ISN'T: This is not a theoretical book. It's not a math book. You won't find any formal justification for the methods outlined in the book because none is necessary for a practical navigator. The book is short and succinct, and it will add little to an experienced navigator's understanding of this topic. 

    So do you need it? Maybe not...

    I bought a copy for my collection of navigation books some fifteen years ago. Back when I first described a complete method of getting longitude by sights near noon (fifteen or more years ago) in NavList messages, it was slammed, as was so common back then, by a couple of NavList members who have since passed away. They had not tried it, of course. They only knew that no real navigator would ever employ such a cheap and easy method of celestial navigation. Celestial navigation cannot be easy. Celestial navigation must be hard, and it must remain so to ensure that the community is not polluted by the un-mathed, incapable of solving a spherical triangle! That was the unfortunate attitude for some armchair navigators back then. I bought and recommended Hewitt Schelereth's book at that time because it was simple evidence that practical navigators could benefit directly from such a method. I can still recommend it today for a quick read, but you may not find it worth the current going price. On the other hand, if this specific topic has long-term interest for you, then you may well want a copy for your collection, too, simply because it's part of the history of the topic from thirty years ago.

    Frank Reed

       
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