The Gregorian Lunar Calendar is indirectly specified by the Easter Computus. There are at least two possible variants: the Tabular Gregorian Lunar Calendar adheres stricly to the Computus exceptions and thus sometimes has months of 28 or 31 days, whereas the Regular Gregorian Lunar Calendar restricts the month length to either 29 or 30 days, usually alternating.
Nomenclature[]
- A year whose corresponding Gregorian Solar Calendar year has 29 February is usually also a leap year in the Gregorian Lunar Calendar, i.e. the second month gets an extra leap day.
- Years with a leap month, i.e. 13 months in total instead of the usual 12, are called embolismic years.
- The 13th or leap month is called embolismic month.
- A long month of 30 days is called a full month.
- A short month of 29 days is called a hollow month.
- A year with the Golden number 19 is called a hollow year, i.e. the last one of a Metonic cycle.
- The Dominical letter (DL) is the DOW designator for the Sundays of the year, running from A to G, where 1 January in the corresponding solar year is always A and 1 March is always D – even in leap years.
- The Gregorian epact is a quasi-numeric label (‘1’…‘29’ and ‘25*’) based upon the numeric Julian epact (1–29) with solar and lunar corrections. The Julian epact has a 1:1 mapping to the Golden Number of the year, the Gregorian epact does not.
- A solar correction is subtracted in every centennial year that is a leap year in the Julian Calendar but not in the Gregorian Solar Calendar, i.e. 3 years within a 400-year cycle.
- A lunar correction is added eight times within a 2500-year cycle, in centennial years 2, 5, 8, 11, 14, 18!, 21 and 24.
Months[]
### | Hebrew | Gaulish | Madore | Germanic | EB | Days | Exceptional length | |
---|---|---|---|---|---|---|---|---|
L01 | Tevet | Shevat | Simivisonnios | Terminus | Wintermonth | 丑 | 30 | 29 when previous year was hollow but not embolismic |
L02 | Shevat | Adar I | Equos | Lipidus | Mudmonth | 寅 | 29 | 30 when the Julian year is leap, but for centennial years only when the sum of corrections is negative |
L03 | Adar | Adar II | Elembivios | Venuch | Springmonth | 卯 | 30 | — |
L04 | Nisan | Edrinios | Amber | Eastermonth | 辰 | 29 | — | |
L05 | Iyar | Cantlos | Pook | Joymonth | 巳 | 30 | — | |
L06 | Sivan | Samonios | Jupe | Ploughmonth | 午 | 29 | — | |
L07 | Tammuz | Dumannios | Tibery | Haymonth | 未 | 30 | — | |
L08 | Av | Rivros | Claudy | Harvestmonth | 申 | 29 | — | |
L09 | Elul | Anagantio | Septil | Windmonth | 酉 | 30 | — | |
L10 | Tishrei | Ogronios | Octil | Vintagemonth | 戌 | 29 | — | |
L11 | Cheshvan | Cutios | Novil | Autumnmonth | 亥 | 30 | — | |
L12 | Kislev | Giamonios | Decil | Holymonth | 子 | 29 | — | |
L13 | — | Tevet | Antaran… | Mercuary | Leapmonth | — | 30 | 29 in hollow years |
The ecclesiatical Paschal full moon is usually on L04-14, only for year epacts 24 and 25* it is in L05-14 – Easter is the following Sunday.
Easter[]
Epact | Paschal moon | A | B | C | D | E | F | G |
---|---|---|---|---|---|---|---|---|
24 | 04-18 | 04-23 | 04-24 | 04-25 | 04-19 | 04-20 | 04-21 | 04-22 |
25 | ||||||||
25* | 04-17 | 04-18 | ||||||
26 | ||||||||
27 | 04-16 | 04-17 | ||||||
28 | 04-15 | 04-16 | ||||||
29 | 04-14 | 04-15 | ||||||
0 | 04-13 | 04-14 | ||||||
1 | 04-12 | 04-13 | ||||||
2 | 04-11 | 04-12 | ||||||
3 | 04-10 | 04-11 | ||||||
4 | 04-09 | 04-10 | ||||||
5 | 04-08 | 04-09 | ||||||
6 | 04-07 | 04-08 | ||||||
7 | 04-06 | 04-07 | ||||||
8 | 04-05 | 04-06 | ||||||
9 | 04-04 | 04-05 | ||||||
10 | 04-03 | 04-04 | ||||||
11 | 04-02 | 04-03 | ||||||
12 | 04-01 | 04-02 | ||||||
13 | 03-31 | 04-01 | ||||||
14 | 03-30 | 03-31 | ||||||
15 | 03-29 | 03-30 | ||||||
16 | 03-28 | 03-29 | ||||||
17 | 03-27 | 03-28 | ||||||
18 | 03-26 | 03-27 | ||||||
19 | 03-25 | 03-26 | ||||||
20 | 03-24 | 03-25 | ||||||
21 | 03-23 | 03-24 | ||||||
22 | 03-22 | 03-23 | ||||||
23 | 03-21 | 03-22 |
Tabular[]
DOM | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
January | 0 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
February | 29 | 28 | 27 | 26 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | — | — | — |
March | 0 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
April | 29 | 28 | 27 | 26 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | — |
May | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 |
June | 27 | 26 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | — |
July | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 |
August | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 | 25 | 24 |
September | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 | 24 | 23 | — |
October | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 |
November | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 | 24 | 23 | 22 | 21 | — |
December | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 |
Each day whose label in the table equals the epact of the year marks the start of a lunar month. If the year has an epact of “25” or “25*”, the day label “25” applies where it exists, but since it is skipped every other time between “26” and “24” (marked by a thick border), the replacement then is “24” for “25” and “26” for “25*”.
Regular[]
Suggested leap-month rule: Years with an epact in
- [0, …, 11] are never embolismic,
- [12, …, 15] are embolismic if the following year is not,
- [16, …, 24, 25*] are always embolismic,
- [25, …, 29] are never embolismic.