The star Regulus is a star that is suspected to be variable and it is the brightest star in the constellation Leo with an apparent magnitude of 1.35, when the Sphinx of Giza was built around 2500 BC Christ, the constellation Leo was at its highest in the sky at midnight on the winter solstice, a precession of the constellation of about one degree per 72 years (due to the precession of the equinoxes or solstices), for 4500 years gives;
(4500 years)/(72 years/degree) = 62.5 years
now the star Regulus is about 30 degrees to the right of the spring equinox, 62.5 degrees + 30 degrees 92.5 degrees to the right of the spring equinox, or almost to the winter solstice, note that (2.5)(72) = 180, maybe the Sphinx of Giza was built in 2320 BC Christ rather than 2500 BC Christ.
Note also that the ancien Egyptians knew the tropical year in 3285 years before Jeus-Christ according the historian Thomas-Henry Martin.
So, why not consider that the star Regulus is a landmark in the sky for the precession of the saisons?
The exact value for right ascension of Regulus is 10 h. 8' 22.311 "
it is about 27.9 degree to right spring equinox, then 27.9 + 62.5 = 90.4
it is close to 90 degrees or to the winter solstice, then 2500 years before Christ is about perfect!
For Sawl, Égypte,
2500 before Christ, 21/12
right ascension : 5h.54'26"
for 2000, right ascension : 10h.9'41.2"