section_path: Abstract
section_name: Abstract
paragraph_text: 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 (1st Thout 1592 AM). This calendar is based on the ancient Egyptian calendar. To avoid the calendar creep of the latter (which contained only 365 days each year, year after year, so that the seasons shifted about one day every four years), a reform of the ancient Egyptian calendar was introduced at the time of Ptolemy III (Decree of Canopus, in 238 BC) 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 25 BC, when the Roman Emperor Augustus imposed the Decree upon Egypt as its official calendar (although initially, namely between 25 BC and AD 5, it was unsynchronised with the original implementation of the Julian calendar which was erroneously intercalating leap days every third year due to a misinterpretation of the leap year rule so as to apply inclusive counting). 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. Its years and months coincide with those of the Ethiopian calendar but have different numbers and names.
  
  Unlike the Gregorian calendar, the Coptic calendar does not skip leap years three times every 400 years, and therefore it stays synchronised with the Julian calendar over a four-year leap year cycle.