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Dear Geoff,

Thank you very much for the time you spent on working the "other" Lunar by Donald B. Prentice.

Yes ... it is absolutely amazing to see with modern astronomy tools that, one Century ago, he did observe this Regulus occultation within half a second of UT time !

Thank you very much also for the Swiss Ephemeris document which - among many other interesting subjects - deals with long term differences between various Ephemeris, a subject which I have always studied with great attention. Definitely yes ! : under the cover of serving Astrology the best they can, both co-Founders are true Modern Astronomers who use Astrology as a pretext to fulfill their passion for reliable Ephemeris over the widest possible time span. As an example, in "2.1.6.  Solar Ephemeris in the remote past" , they demonstrate excellent knowledge of this often overlooked fact which constitutes a solid independent tool to check the quality of a numerical integration : the Moon Mean Orbital Plan lies [exactly] in the Mean Equator of Date - it could be even said that it actually defines it - which MEoD is an inertially moving plan in reference to the various 2000.0 "fixed" plans. Why so ? Simply because Numerical Integrations are carried out in a fixed plan [currently 2000.0]. As an immediate consequence of this Moon trajectory, the Ecliptic of Date Sun Latitude remains bounded within the [-1.2" / +1.2"] limits even in the remote periods, e.g. 10,000 BC. *****

So much for me to read and learn here ... in this 67 page document.

Thanks again to you Geoff, and congratulations to you Mr Donald B. Prentice for your exceptional observing skills.

Best Astronomical Regards

Kermit

***** And by the way, DE431 - covering years -13,200 to +17,191 - does remain an outstanding long term planetary theory.