Ancient egyptian dating system
This pre-dates the Julian reform of 46 BCE which Julius Caesar introduced on the advice of the Alexandrian astronomer Sosigenese.Reform did, however, come after the defeat of Cleopatra and Anthony by the Roman General (and soon to be Emperor) Augustus in 31 BCE.(This is most unusual since other civilizations of that era are known to have started months with the first setting of the new crescent!) A thirteenth month was intercalated to maintain a link to the heliacal rising of Serpet. The second calendar, used for administrative purposes, was based on the observation that there was usually 365 days between the heliacal rising of Serpet.In the following year, the Roman senate decreed that the Egyptian calendar should include a leap year, although the actual change to the calendar didn't occur until 23 BCE.The months of the Egyptian civil calendar were further divided into three sections called "decades", each of 10 days.It was based on a period of 25 civil years which was approximately equal 309 lunar months.An attempt to reform the calendar to include a leap year was made at the beginning of the Ptolemaic dynasty (Decree of Canopus, 239 BCE), but the priesthood was too conservative to allow such a change.
The first was a lunar calendar based on 12 lunar months, each of which began on the first day in which the old moon crescent was no longer visible in the East at dawn.These equinoctial hours, so called because they are based on the equal length of day and night at the equinox, split the day into equal periods.