Coptic calendar
The Coptic calendar, also called the Alexandrian calendar, is a liturgical calendar used by the farming populace in Egypt and used by the Coptic Orthodox and Coptic Catholic churches. It was used for fiscal purposes in Egypt until the adoption of the Gregorian calendar on 11 September 1875. Like the Julian calendar, the Coptic calendar has a leap year every four years invariably; it does not skip leap years three times every 400 years.
Origin
This calendar is based on the ancient Egyptian calendar. This calendar contained only 365 days each year, year after year, so that the date relative to the seasons shifted about one day every four years. To avoid the "creep" of the latter around the seasons, a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III which consisted of adding an extra day every fourth year. However, this reform was opposed by the Egyptian priests, and the reform was not adopted until the Roman Emperor Augustus decreed that Egypt must adopt the system as its official calendar.To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic or Alexandrian calendar and its epoch equates to 29 August 284AD. The neighbouring Ethiopian calendar is very similar to the Coptic calendar, except that it has a different epoch and different names for the days of the week and months of the year.
Coptic year
The Coptic year is the extension of the ancient Egyptian civil year, retaining its subdivision into the three seasons, four months each. The three seasons are commemorated by special prayers in the Coptic Liturgy. This calendar is still in use all over Egypt by farmers to keep track of the various agricultural seasons.The Coptic calendar has 13 months, 12 of 30 days each and one at the end of the year of five days. The Coptic Leap Year follows the same rules as the Julian Calendar so that the extra month always has six days in the year before a Julian Leap Year.
The year starts on the Feast of Neyrouz, the first day of the month of Thout, the first month of the Egyptian year. For 1900 to 2099 it coincides with the Gregorian Calendar's 11 September, or 12 September before a leap year. For any year, it coincides with the Julian Calendar's 29 August, or 30 August before a leap year. Coptic years are counted from 284 AD, the year Diocletian became Roman Emperor, whose reign was marked by tortures and mass executions of Christians, especially in Egypt. Hence, the Coptic year is identified by the abbreviation A.M.. The first day of the first year of the Coptic era was 29 August 284 in the Julian calendar. To obtain the Coptic year number, subtract from the Julian year number either 283 or 284.