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    Ocean Navigator - June 2010
    From: Andrés Ruiz
    Date: 2010 Jun 3, 08:03 +0200

    Ocean Navigator - June 2010

    Two articles from our friends John Karl and Greg Rudzinski!!!

     

    Celestial Navigation

    by David Berson

     

    The benefits of using H.O. 249 for Selected Stars

    There is no greater thrill for the evolving celestial navigator than in obtaining a fix from a star sight. This is the navigational sine qua non and the goal to which navigators aspire. The most difficult aspect of taking star sights — especially if you are older than age 50 — is finding the stars, recording the time, and getting a sextant altitude observation (Hs) in dim light. With or without glasses it can still be a chore. The stars, it might be said, are for young eyes, but with a good red-light flashlight and some practice the physical act of shooting stars can be learned!
        The easiest and most fool-proof method requires the use of H.O. 249 Vol. 1, Selected Stars. This volume is published in 10-year editions called epochs — the latest version having come out in 2010. The table is laid out with latitude pages from 89° North to 89° South. The local hour angle (LHA) of Aires for seven stars is listed from 0° to 359°. The seven stars have been chosen for their magnitudes (brightness) and for their ability to give the navigator good cuts — they are positioned about 45° relative to each other. 
    Continue reading…

     

    About the Author:
    Contributing Editor David Berson writes the Nav Problem page in every issue of Ocean Navigator. He is also the owner and operator of Glory, an electrically powered excursion boat, in Greenport, N.Y.

     

    Questions or comments for Dave? editors@oceannavigator.com

     

     

    More Ocean Navigator articles:

     

    The sextant's compromising views
    by John Karl
    When it comes to celestial navigation, a prime question from both experienced navigators and celestial-navigator wannabes is this: What’s the best sextant? This question leads to a compromise among four possible combinations of horizon mirrors and telescopes. In writing my recent book, Celestial Navigation in the GPS Age, I’ve studied these four combinations using nine different sextants, giving me definitive but compromising views. Continue reading…

     

    Star finder tip
    by Greg Rudzinski
    There is more than one way to spin a Rude star finder. Try the following technique the next time you shoot a round of stars. Continue reading…

     

     

    How bright is bright
    by Tim Queeney
    At one time or another, virtually all celestial navigators have looked at the data for the navigational planets and puzzled at the cryptic numbers alongside the names. Some numbers are positive, and some are negative, and they change over the course of the year. When he asks about these labels, the navigator is told that the numbers represent "magnitude," or the apparent brightness of the planets. And it helps not at all to be further informed that the larger the negative number, the brighter the object. Continue reading…

     

       
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