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    Re: David Thomson and his lunar tables
    From: Antoine Couëtte
    Date: 2010 Mar 17, 14:58 -0700

    Interesting Lunar indeed ...

    With the following reasonable assumptions that :

    - the indicated sextant values are corrected for Instrument error, and
    - the observer's height of eye is close to 14 feet, and
    - both Lunar distance and Moon + Sun Altitudes took place at the same instant, and
    - delta T = 12.5 s, then with the following :

    Sun-Moon Distance = 71°56', Sun Height LL = 55°36' , and Moon UL = 38°35',

    and with to-day computing tools, we get an observation date of Sep 15, 1809 (and not Sep 16 th, as seems to be indicated ), a UT time of 09h41m32.9s with an observed position as follows:

    S 27°47'6 and E 048°34'8 for an account longitude equal to 48°40' (he found longitude equal to E048°45'). So this sharp Observer was definitely within 5 minutes in Longitude from his DR.... Whaooo !!!

    Some more examples ? :-)) ....

    Best Regards

    Antoine M. "Kermit" Couëtte
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