LYCOS RETRIEVER 
Julian Calendar: Western Easter
built 807 days ago
While the Julian reform applied originally to the Roman calendar, many of the other calendars then used in the Roman Empire were aligned with the reformed calendar under Augustus. This led to the adoption of several local eras for the Julian calendar, such as the Era of Actium and the Spanish Era, some of which were used for a considerable time. Perhaps the best known is the Era of Martyrs, sometimes ... called Anno Diocletiani (after Diocletian), which was often used by the Alexandrian Christians to number their Easters during the fourth and fifth centuries and continued to be used by the Coptic and Abyssinian churches.
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You can generate a calendar that is valid for most OrthodoxChurches, which still use the Julian Calendar. The current method of calculating Easter was first instituted by the Council of Nicea in AD325.
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[J]ust three Churches decided on that Council to stick to the Julian calendar: Serbian, Russian and Jerusalem (as well as all the monasteries on the Holy Mountain). However, it was agreed that all Orthodox Churches celebrate Easter the old way, regardless of the time difference in celebrating the Fixed Feasts (the biggest being Christmas),.
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Alex ... provided the following algorithm that is based on the algorithm derived by the German mathematician Gauss, the principal simplification is that substitutions have been made for the case of Julian calendars and Orthodox Easters. This algorithm calculates the number of days AFTER March 21 (Julian) that Easter occurs (Note: It is a much simpler calculation than the Western Easter).
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Western Easter