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    Re: Equinox Sun sights tomorrow
    From: Paul Hirose
    Date: 2022 Mar 20, 15:39 -0700

    On 3/20/2022 5:45 AM, David C wrote:
    > Lat 41S
    >
    > Long 175° E
    >
    > An extra question is when will the equinox be at 0027 UT allowing me to
    > take a noon sight at the equinix?
    
    You can get pretty close on 2026 September 23, when the equinox occurs
    at 00:06 UT1. At your local noon,
    
    2026-09-23 12:00:00.00 LAT
    2026-09-23 00:12:32.72 UT1
    2026-09-23 00:13:42.96 TT
    
    Sun topocentric apparent place
      49°00.02' unrefracted center altitude
       0°00.00' azimuth
    
    Sun geocentric apparent place
    180°00.27'  -0°00.12' equinox RA, dec
    180°00.30'  -0°00.00' ecliptic true lon, lat
    
    
    My solstice and equinox page has a table of the phenomena for the next
    10 years. You can find that everywhere, but I also discuss related
    matters. Any of four different angles could plausibly define a solstice
    or equinox. Which is the formally correct angle to use? Difficulties
    with the UT1 and UTC time scales. Why give long term predictions in TAI?
    Attainable accuracy in predictions. Example calculation.
    
    http://sofajpl.com/solstice/
    
    I believe minor discrepancies in solstice and equinox times are usually
    due to differences in computation of Earth orientation: precession,
    nutation, and obliquity. The Sun ephemeris has less effect. At a
    precision of one second of time, the late 1990s JPL DE406 gives results
    virtually identical to recent ephemerides at epochs not far from the
    present.
    
    --
    Paul Hirose
    sofajpl.com
    

       
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