heliacal

I do not see how the heliacal rising of Sirius in any one year could help them to determine its length.

From Personal Recollections, from Early Life to Old Age, of Mary Somerville by Mary Somerville

In Egypt, another reason was, that then the Nile began to overflow, at the heliacal rising of Sirius.

From Morals and Dogma of the Ancient and Accepted Scottish Rite of Freemasonry by Albert Pike

Brugsch states that the appearance of the said new moon, which was also associated with the heliacal rising of Sirius, would range from Aug.

From The Fundamental Principles of Old and New World Civilizations by Zelia Nuttall

Swart star: the Dogstar, called swarthy because its heliacal rising in ancient times occurred soon after mid-summer. moist vows: either tearful prayers, or prayers for one at sea.

From The Golden Treasury Of the Best Songs and Lyrical Poems in the English Language by Francis Turner Palgrave

According to an extremely ancient belief it was the goddess Hathor Isis-Sothis who caused the inundation of the Nile which, according to the inscriptions, coincided with the heliacal rising of Sirius.

From The Fundamental Principles of Old and New World Civilizations by Zelia Nuttall