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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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