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    Re: Modern Lunars
    From: Paul Hirose
    Date: 2016 Sep 25, 16:44 -0700

    On 2016-09-25 3:08, Antoine Couëtte wrote:
    > BTW, could you *not* perform the Moon "center of mass to center of figure 
    correction" more accurately now since the most recent modern Theories also 
    give Libration angles. *Yes?*
    
    It's true that many (not all) JPL ephemerides include the libration
    angles. No doubt accuracy would improve if they were applied to a
    mathematical model of the limb. But I think even the standard fixed
    corrections of +0.5″ in longitude and -0.25″ can be ignored in most
    lunar distance computations.
    
    My software has an option (by default it's not selected) to apply them
    if the user wants extra accuracy. A sextant is readable to 6″, and my
    goal is 0.6″ accuracy. (There is a rule of thumb in electronics that
    test equipment should be 10x better than the device under test.) I think
    we can hit that target, or get pretty close, with the standard corrections.
    
    I'm surprised that you didn't comment on the 0.0002° systematic
    discrepancy in our topocentric apparent unrefracted Moon position in the
    1855 lunar. That's 0.7″.
    
    > Modern computing power enables to tackle Lunars [much] better than the 
    Classical Methods could and can [ever] do it. The Sextant "Observed Refracted 
    Distances" have now become the main computation variables and benchmarks. No 
    longer need to use the Classical [and formerly unavoidable] intermediate 
    variables - i.e. the "*Cleared Distances*" - which sometimes vary with Time 
    (UT1) in a manner totally different from their Observed Sextant Distances 
    counterparts.
    
    I've never seen any evidence that the "modern lunar" has a significant
    advantage over the traditional solution if you avoid unfavorable
    altitudes and separation angles. I'm open to the possibility, but skeptical.
    
    > *** from "**About Lunars**" by our [very] much regretted George Huxtable who 
    was the first one actually whom I personally contacted about Lunars.
    
    Dear old George, gone but not forgotten.
    
    

       
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