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    How close without a good Lunar?
    From: Mark Coady
    Date: 2018 Jul 23, 19:39 -0700

    I've been mulling this one for the last few weeks without real time to play. I'm afraid I'm about to make an ass of myself...but what the heck...never stopped me before...

    Careful Lunars does a fine job of ocean navigation.  I've had success with a good sextant.

    Lets say my clock goes amuck..I sleep unaware for some crazy hours....and its just that time of month when Lunars just aren't happening.  So I wake up...make a guess and reset my clock...I should have a dead reckoning Longitude.  

    I do have cues that I am right or wrong. If I know my latitude, thats a start. Lets say I know I am North of the equator, somewhere approaching the east coast of North America. To be absurd:If it's dark out..and my assumed local time is noon...well...ok time to guess agian...

    let's say I'm lucky, and I have four planet's visible at one time...... and a good compass...

    my mind keeps saying well...I can take bearings on four planets, and altitudes, and I certainly can get latitude and some good stars.

    My mind keeps saying if I know exactly the altitude and bearing of enough bodies simultaneously..and plot on a known latitude line...then surely I can use this set of relationships can help me zero up my clock.to some proximity without a Lunar....there must be only one geographic position (longitude) and instant in time the multiple bearings and altitudes could all exist. 

    I mean, even more complex is based on the relative near proximity of planets and distant star field....the relative positon of planets to background stars ...  if looked at simultaneously...would provide a unique position plot...

    Then my mind says to me..Dummy.....If that were so very true....the Harrison wouldn't have needed to spend so much time building those lovely little timepieces of his....  except maybe he didn't have a handy little silcon brain to run the umpteen zillion iterations for a single calculation of position. 

    Are my visualization skills that bad, or is it just that the math gets so daunting nobody would attempt it without a dedicated computer?

       
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