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    Re: Latitude and Longitude by "Noon Sun"
    From: Lu Abel
    Date: 2005 Jun 5, 20:45 -0700

    To all who have commented on this thread (noon sights vs LOP sights):
    
    Aren't we forgetting something *very* fundamental?
    
    A good navigator uses ALL available sources of input to ensure good
    navigation!!
    
    I don't see noon sights vs LOP sights as an either-or proposition -- at
    least not for a "good" navigator (which I hope all on this list would
    claim they either are or aspire to).   Instead, a good navigator would
    take noon sights "if appropriate," and LOP sights "if appropriate" --
    where "if appropriate" depends entirely on the particular situation of
    the boat.  If the sun almost surely comes out at noon on overcast days
    (as one distinguished member of this list claimed), grab a noon shot --
    and worry about whether one can observe the sun for long enough to get a
    rough longitude.  If one is blessed with clear weather and a quarter
    moon, why rely on days-old DR, get the world's easiest two-body fix!
    And so on...
    
    Navigation is a very conservative profession, as it should be.  But it's
    important to understand the whys and wherefores of our conservative
    methods to understand their appropriateness in a current context.
    
    Noon sights occupied an important spot in the historical constellation
    of celestial techniques not because they somehow yielded superior
    navigational information, but because they were extremely simple to
    reduce.  In the days when it was very hard to reduce LOP sights, the
    simplicity of noon sight reduction might have been a good tradeoff
    versus the great difficulty in squeezing longitude from it.  Today --
    whether one favors pocket calculators or HO249 (or even HO229!) -- sight
    reduction is much simpler.  IMHO (your mileage may vary) that means the
    traditional noon sight has little advantage (other than "the sun always
    comes out at noon") and maybe some disadvantage over LOP sights.
    
    But, again -- the good navigator will use "appropriate" sights.
    
    Lu Abel
    
    Robert Eno wrote:
    > An old friend of mine, who passed away a few years ago, and who was an
    > experienced navigator for over 60 years, once told me that the noon sun
    > shot
    > was overrated; that all you had to do was to take a few shots with an
    > interval of 2 - 3 hours then transfer one of the LOPs. Fred and a number of
    > other list members seem to agree, and so too, do I.
    >
    > Mind you the noon sun shot is fun to do and very simple to calculate. For
    > this reason, it should remain as one of the basic mainstays of
    > astro-navigation, however, taking and reducing a sun shot at any other time
    > is painfully easy with calculators and with HO 249 (AP3270 in Britain and
    > Canada).
    >
    > George has a very good point about crossing the ocean without GPS and with
    > someone who only knows how to take a noon sight. This is something I
    > harp on
    > when discussing GPS with the uninitiated. The argument that some students
    > will be detracted from learning astro-navigation if things become too
    > complex has merit, however, my response would be that I would not bother
    > wasting my time in trying to train someone who is not committed to learning
    > it properly. No pain, no gain.
    >
    > I won't delve into the "what ifs" (what if my watch went overboard etc.).
    >
    > Robert
    >
    
    
    

       
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