Egyptian priests noticed a link between the appearance of this "dog star" & the flooding of the Nile
Ancient time keepers were usually Sages, Magi, or astrologer-priests who 
... they began to notice the "Dog Star" Sirius rising next to the Sun every 365 days
,... [DOC] [TLE] About Sirius, the brightest star in the night sky - Sirius Digital Archiving [PAR] Sirius is called the Dog Star because of its prominence in the constellation of ... 
the pre-dawn sky signalled the start of the flooding season for the Nile river, ...