The portent began on April 17 of 6 BCE (with the heliacal rising
of Jupiter that morning, followed, at noon, by its lunar occultation in the constellation Aries) and lasted until December 19 of 6 BCE (when Jupiter stopped moving to the west, stood still briefly, and began moving to the east, as compared with the fixed background stars).
And yet, the heliacal rising
of Sirius that occurred on or about a certain specific date every year would actually move forward one day every four years with the clerical 365-day calendar of the Egyptians, so that by the time of the post-Alexandrian pharaohs it was deemed so badly in need of reform that, once and for all, the ecclesiastic year was decreed that it should conform with the civil year.
The Dog Days and the heliacal rising
. The term "Dog Days," used since at least the period of Ancient Greece, refers to the hottest and sultriest part of the summer.
Luft's analysis shows that this festival was dated by the lunar calendar and occurred before the heliacal rising
Egyptians therefore held their New Year celebration at the time of this heliacal rising
Julius Caesar held that the heliacal rising
of the Pleiades (meaning the first date each year when they could be seen in the east before sunrise) marked the beginning of summer.
(In traditional Maori society, a watchful eye is kept on the evening sky following the heliacal rising
of Matariki to spot the appearance of the next new Moon.
The line coincides with summer solstice on Mars 500,000 years ago, and the same vista incorporates the heliacal rising
The ancient Egyptians marked the start of their new year by the heliacal rising
(first appearance in the glow of sunrise) of Sirius.
Because the count was roughly a quarter-day short of the true length of the year, the heliacal rising
of Sirius drifted through the solar calendar and did not recur on the first day of the year until 1,461 of those 365-day years had elapsed.
the heliacal rising
(in the eastern skies) to an astrologer.