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    Re: Occultations of stars by the Moon
    From: Geoff Hitchcox
    Date: 2023 Oct 20, 17:00 -0700

    Bonjour Kermit,

    You wrote

    ================== 

    Maybe one last request then if you do not mind ...

    Would you be so kind as to process the "other" Lunar by Donald B. Prentice.

    ==================

    No problem Kermit, but if you want a highly accurate and TRUE Horoscope - that will cost you a King's Ransom ;-)

    If we 'copy and paste' the following line into the online Swiss Ephemeris , into the box called "other options" 

    -ejpl -occult -pf -b01.01.1924 -local -xfRegulus -geopos-71.399794,41.837667,69

    we get:

    ==================

    geo. long -71.399794, lat 41.837667, alt 69.000000

    total(sunrise)   23.10.1924   11:34:49.7 1.000000 2424081.982520

    73 min 27.95 sec   10:58:23.5    10:58:23.5    12:11:51.5    12:11:51.5  dt=23.7

    ==================
    Now this to me is fascinating:
    10:58:23.5 = Swiss Ephemeris (from above)
    10:58:23.0 = Actual timed measurement by  Donald B. Prentice (in 1924), who said "I believe this is within 3/4" of being correct".
    I think the *Gold Standard* for Occultation predictions today would be Dave Herald's OCCULT (Windows based software) which although FREE and very comprehensive - is Windows only, and uses a Microsoft Library. Whereas I assume SWE is treating "Lady Moon" as a perfect sphere - rather than considering actual Lunar topography. 
    The above measurement by Mr Prentice is amazing Kermit - considering how close this was to Sunrise.
    I also did not realise that 'JPL Horizons' and the 'Nautical Almanac' use a slightly 'different reference ecliptic', as mentioned here:

    The Swiss Ephemeris Compared with Astronomical Almanac and JPL Horizons

     
    Regards, Geoff Hitchcox, Christchurch, New Zealand.
       
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