Dionysian period

Dionysian period, in the Julian calendar, a period of 532 years covering a complete cycle of New Moons (19 years between occurrences on the same date) and of dominical letters—i.e., correspondences between days of the week and of the month, which recur every 28 years in the same order. The product of 19 and 28 is the interval in years (532) between recurrences of a given phase of the Moon on the same day of the week and month. This period is called Victorian for the astronomer Victorius of Aquitaine, its first calculator (c. ad 465); Dionysian for Dionysius Exiguus, who revised Victorius’ figures in the 6th century; and Great Paschal because of its use in determining the date of Easter.