Beginning in the medieval period the age of the ecclesiastical moon was announced daily in the office of Prime at the reading of the martyrology.
[1] In the Book of Common Prayer of the Protestant Episcopal Church of the United States of America, the dates of the paschal full moons for the 19 years of the Gregorian Easter cycle are indicated by the placement of the Golden Number to the left of the date in March or April on which the paschal full moon falls in that year of the cycle.
The date of Easter is determined as the first Sunday after the "paschal full moon" that falls on or after March 21.
This "full moon" does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, determined from tables.
[6] The motivation for these experiments was a dissatisfaction with the Jewish calendars that Christians had hitherto relied on to fix the date of Easter.
The Christians who began the experiments with independent computations held that the paschal full moon should never precede the equinox.