accuracy of the Gregorian ecclesiastical lunar calendar is remarkable. It will be in error by one day in about 73 500 years while the error with respect to the tropical year will be one day in about 3320 years. The following table gives the ecclesiastical new moon used for determining Easter (in the Gregorian system) for a range of years. References External links U.S. Naval Observatory Data Services Gregorian ecclesiastical new moons Oxford, Bodleian Library MS. Lat. liturg. e. 6. (14th century) Easter date New moon