Hi Nephele,
The ancient Greek poet Hesiod wrote The Works and Days, and listed days on which it is best to pursue various activities, such as harvesting grapes and defined them according to the rising of a particular star:- "When Orion and Sirius shall have reached mid-heaven, then oh Perses, gather your grapes and bring them home".
Here is something interesting, in looking at the start of the Julian Calendar, Pliny had something to say about Julius Caesar, which is as follows:- "There were three main schools, the Chaldeans, the Egyptians and the Greeks, and to these a fourth was added in our country by Julius Caesar during his dictatorship, who with the assistance of the learned astronomer, Sosigenes, brought the separate years back into conformity with the course of the Sun!"
Obviously Pliny was talking about the events starting the Julian calendar, but more interestingly, did he mean Caesar had started a new mystery school dedicated to the Isis star, Sirius?
Sosigenes was Cleopatra's astronomer and had spent his time studying in the great library in Alexandria, sadly burned down in later centuries. He had a good grasp of astronomy, as the Julian Calendar was only out of true by 11 minutes, not bad for over 2,000 years ago, considering until quartz watches, we were unlikely to own a watch that was accurate to 11 minutes in a year!
Without going into the politics of the meeting of Cleopatra and Julius Caesar, which all the learned members know, lets pick out a few points in a general way.
1)Cleopatra was extremely political and saw that having babies with important Romans could see her children on the throne of Rome, she threw the dice and lost!
2)It seems that Julius Caesar was interested in the god kings that he vanquished in his military career, and especially interested in Cleopatra, who he had a son by, named Caesarion.
The senate suspected that he wanted to be a god king, which obviously they would find dangerous, in fact it was one of the reasons that he was assassinated.
3)The Greek ploemaic rulers had seen that the Egyptian calendar was nearly exact in around 238 BC, and had tried to add a leap day every four years, however the secretive priests of Thoth and the Egyptian populance didn't want their sacred calendar messed with, so it was put on hold till Julius Caesar arrived in Egypt.
4)The Egyptian New Year was governed by the Sothic Cycle, didn't have a leap day every 4 years, thus was a wandering year, so the First of Thoth being New Year only occured with the heliacal rising of the Isis star once in 1460 years, however if a new calendar was introduced i would expect it to start with an alignment between Sirius and the Sun, involving Egyptian beliefs!
5)Julius Caesar chose 1st January as New Year, probably as since 0153 BC that Roman consuls had taken office on that date, however Sosigenes was CLEOPATRA'S ASTRONOMER, therefore tuned to her beliefs. The Roman calendar was hopeless, and it was difficult to know where 1st January fell in it, indeed Sosigenes had to make 0046 BC 445 days long, so he could have tinkered with this to promote Egyptian beliefs, whether Julius Caesar know what he was doing, i cannot say!
6)Both Sosigenes and Cleopatra were Greek, the last pharoah was very involved with the Egyptian religion, she often dressed as Isis, and was thought of as Isis on Earth by her subjects. She was clever as she spoke nine lanquages.
7) Midnight wasn't used as the start of the day, that early as it was difficult to measure using water clocks, Romans and Egyptians used Sunrise, Babylonians and Greeks used Sunset as the start of the day....indeed Israel uses Sunset even today.
8) As Cleopatra was Greek perhaps she used Sunset to start the Julian calendar, to leave an alignment for the Isis Cults, so we wouldn't be looking at sunrise on 1st January 0045 B.C., we would be looking for the location in Egypt that Sosigenes picked to view the stars from at Sunset on 31st December 0046 B.C.
9)The three main locations in Egypt at that time were Alexandria, Memphis or the ancient capital Thebes now called Luxor which is 25*N41' 32*E39'
There is only one place where Sirius has any connection during this date in history, Being Thebes/Luxor, the ancient Capital of Egypt, near the sacred temples of Karnak, and not far from the Valley of the Kings!
Ask an astronomer, exactly at 17:19pm on 31st December 0046 BC, the Sun set at the location of Thebes, as it set, Sirius the Isis star was rising in the East along the horizon!
I have no idea if Julius Caesar knew this, the calendar he brought back to Rome was set to sunrise, so this alignment was secret, joining Egyptian and Greek mythology at the start of the day valued by the Greeks!
Web-link to Greek start of day, please scroll down.
www.wikipedia.org/wiki/Ancient_Greek_weights_and_measures