Calendar Systems

Ab Urbe Condita (See Roman Calendar)

Aztec Day Count (See Aztec Calendar – Tonalpohualli)

Aztec Calendar – Tonalpohualli

Other Names: Also called the Tonalpohualli, Tonalpohualli Calendar, Day Count.

Origin: The Aztec Tonalpohualli Calendar is very similar to the Mayan Tzolkin Calendar (see Mayan Calendar – Tzolkin). It was the sacred calendar of the Aztecs.

Method: 260-day cycle. The Tonalpohualli Calendar used two independent cycles which advanced simultaneously – a thirteen-day count and a twenty-name cycle. The names are as follows:

� Cipactli (Crocodile) (protected by Tonacatecuhtli),

� Ehecatl (Wind) (protected by Quetzalcoatl),

� Calli (House) (protected by Tepeyollotl),

� Cuetzpalin (Lizard) (protected by Huehuecoyotl),

� Coatl (Snake) (protected by Chalchihuitlicue),

� Miquiztli (Death) (protected by Tecciztecatl),

� Mazatl (Deer) (protected by Tlaloc),

� Tochtli (Rabbit) (protected by Mayahuel),

� Atl (Water) (protected by Xiuhtecuhtli),

� Itzcuintli (Dog) (protected by Mictlantecuhtli),

� Ozomahtli (Monkey) (protected by Xochipili),

� Malinalli (Grass) (protected by Patecatl),

� Acatl (Reed) (protected by Tezcatlipoca),

� Ocelotl (Jaguar) (protected by Tlazolteotl),

� Cuauhtli (Eagle) (protected by Xipe Totec),

� Cozcacuauhtli (Vulture) (protected by Itzpapalotl),

� Ollin (Movement) (protected by Xolotl),

� Tecpatl (Stone Knife) (protected by Chalchihuihtotolin),

� Quiahuitl (Rain) (protected by Tonatiuh), and

� Xochitl (Flower) (protected by Xochiquetzal).

The count and names advance independently, thus 13 Tecpatl is followed by 1 Quiahuitl, which is followed by 2 Xochitl, which is followed by 3 Cipactli, etc. This results in 260 distinct dates.

Mathematics: 13×20=260

Years: At the end of its cycle, the Tonalpohualli Calendar merely resets; there is no system (analogous to counting years) for distinguishing one Tonalpohualli Calendar cycle from another.

Days: A day is called a tonal.

Correlation to Gregorian: On NS January 1, 1997 CE, the trecenas (13-day period) was Xochitl, and

the tonal (day) was 8 Mazatl.

Other Cycles: The Tonalpohualli Calendar also recognized 13-day trecenas, which began each time the day number cycled to 1 and the names of which corresponded to the day name of that first day of the

trecenas:

� 1-Cipactli (Crocodile) (protected by Tonacatecuhtli & Tonacacihuatl),

� 1-Ocelotl (Jaguar) (protected by Quetzalcoatl),

� 1-Mazatl (Deer) (protected by Tepeyollotl & Tlazolteotl),

� 1-Xochitl (Flower) (protected by Huehuecoyotl & Ixnextli),

� 1-Acatl (Reed) (protected by Chalchihuitlicue),

� 1-Miquiztli (Death) (protected by Tonatiuh & Tecciztecatl),

� 1-Quiahuitl (Rain) (protected by Tlaloc),

� 1-Malinalli (Grass) (protected by Mayahuel & Xochipilli),

� 1-Coatl (Snake) (protected by Xiuhtecuhtli & Tlahuizcalpantecuhtli),

� 1-Tecpatl (Stone Knife) (protected by Mictlantecuhtli & Tonatiuh),

� 1-Ozomahtli (Monkey) (protected by Patecatl),

� 1-Cuetzpalin (Lizard) (protected by Itzlacoliuhqui & Tezcatlipoca),

� 1-Ollin (Movement) (protected by Tlazolteotl),

� 1-Itzcuintli (Dog) (protected by Xipe Totec & Quetzalcoatl),

� 1-Calli (House) (protected by Itzpapalotl),

� 1-Cozcacuauhtli (Vulture) (protected by Xolotl & Tlalchitonatiuh),

� 1-Atl (Water) (protected by Chalchihuitotolin),

� 1-Ehecatl (Wind) (protected by Chantico),

� 1-Cuauhtli (Eagle) (protected by Xochiquetzal), and

� 1-Tochtli (Rabbit) (protected by Xiuhtecuhtli & Xipe Totec).

Aztec Calendar – Xiuhpohualli

Other Names: Also called the Xiuhpohualli, Xiuhpohualli Calendar.

Origin: The Aztec Xiuhpohualli Calendar is very similar to the Mayan Haab Calendar (see Mayan Calendar – Haab). Some of their systems of reckoning are identical, but their years do not always coincide.

Method: Solar.

Mathematics: 18×20+5=365

Years: The Xiuhpohualli counts days and months, but years are only designated only as Xihuitl or

"Agricultural Years." The name of the Xihuitl is taken from the Aztec Tonalpohualli (see Aztec Calendar – Tonalpohualli) day that corresponds to the last day of the last month of the Aztec Xiuhpohualli Calendar, for example 1 Calli. Thus, the number comes from the number of the day in that calendar – between 1 and 13 inclusive. The day, likewise, comes from the name of the day in that calendar; in practice, however, only four names are possible:

� Calli, � Tochtli, � Acatl, and

� Tecpatl.

Months: The Aztec Xiuhpohualli Calendar has 18 months of 20 days each, along with a 5-day period to complete the year.

Days: A day is called a tonal.

Conformity to Solar Year: A 5-day period was added at the end of the year to bring it up to 365 days.

Intercalary/Leap System: The Aztec Xiuhpohualli Calendar year was 365 days; no effort was made to add a day to prevent its slow drift backward through the seasons.

Correlation to Gregorian: On NS January 1, 1997 CE, the Xihuitl (agricultural year) was 11 Calli.

Other Cycles: A cycle of 52 years is called a bundle.

Holidays: Holidays occurred at the end of each month.

Babylonian Calendar

Method: Solar.

Months: The Babylonian Calendar used lunar months, and added extra months when necessary to keep the calendar in line with the solar year.

Correlation to Gregorian: Year 2745 of the Babylonian Calendar began on NS April 24, 1996 CE.

Badí Calendar (See Bahá'i Calendar)

Bahá'i Calendar

Other Names: Also Called the Badí Calendar.

Origin: The Bahá'i Calendar is based on the number 19 (the number of years between which the Báb foretold the prophet, and Bahá'u'lláh's announcement of his mission). The Bahá'i Era began in 1844 CE (AH 1260), the year of the Báb's prophecy.

Method: Solar. Nineteen months of nineteen days each, with a period of 4 days (5 days in leap years) to bring the calendar to 365 days.

Mathematics: 19×19+4=365 (common year) 19×19+5=366 (leap year)

New Year: The beginning of the year (Naw Rúz) corresponds to NS March 21. (Some sources indicate that the year begins on the vernal equinox rather than correlating exactly to the date of NS March 21.)

Years: Years in the Bahá'i Calendar are followed by the abbreviation BE (for "Bahá'i Era").

Months: The year consists of 19 months of 19 days each. The names for the months are drawn from the nineteen names of God invoked in a prayer said during the month of fasting in Shí'ih Islam. Respectively, they are:

� (1) Bahá (Splendor),

� (2) Jalál (Glory),

� (3) Jamál (Beauty),

� (4) 'Azamat (Grandeur),

� (5) Núr (Light),

� (6) Rahmat (Mercy),

� (7) Kalimát (Words),

� (8) Kamál (Perfection),

� (9) Asmá' (Names),

� (10) 'Izzat (Might),

� (11) Mashíyyat (Will),

� (12) 'Ilm (Knowledge),

� (13) Qudrat (Power),

� (14) Qawl (Speech),

� (15) Masá'il (Questions),

� (16) Sharaf (Honor),

� (17) Sultán (Sovereignty),

� (18) Mulk (Dominion), and

� (19) 'Alá (Loftiness) (month of fasting from sunrise to sunset).

Days: Days run from sunset to sunset, and each day of the month is given a name in the same sequence as the names of the months, so the first day of the new year can be know as either 1 Bahá or the Bahá day of the Bahá month.

Additionally, the Bahá'i Calendar follows a seven-day week, the days of which are:

� Jalál (Glory) (Saturday),

� Jamál (Beauty) (Sunday),

� Kamál (Perfection) (Monday),

� Fidál (Grace) (Tuesday),

� 'Idál (Justice) (Wednesday),

� Istijlál (Majesty) (Thursday), and

� Istiqlál (Independence) (Friday) (day of rest).

Therefore, each day has two names, one for its sequence in the month and the other for its sequence in the 7-day week.

Conformity to Solar Year: In order to bring the year up to 365 days (or 366 days in leap years), a period

is inserted before 'Alá (the month of fasting), called Ayyám-i-Há. Literally this means "Days of 'Há,'" because in the abjad system the letter Há has the numerical value of 5.

Intercalary/Leap System: Ayyám-i-Há has 4 days in ordinary years and 5 days in leap years, which

correspond to the Gregorian Calendar insofar as to make Naw Rúz fall on NS March 21. (Presumably for those who fix the Bahá'i Calendar to begin on the actual vernal equinox rather than NS March 21, the leap year would not, in fact, correspond to the Gregorian Calendar system.)

Correlation to Gregorian: The Bahá'i year 152 BE began (1 Bahá, 152 BE) at sunset the night before NS March 21, 1995 CE.

Other Cycles: Each cycle of nineteen years is called a Váhid. The names of the years of the Váhid are:

� (1) Alif (The Letter "A"),

� (2) Bá (The letter "B"),

� (3) Ab (Father),

� (4) Dál (The letter "D"),

� (5) Báb (Gate),

� (6) Váv (The letter "V"),

� (7) Abad (Eternity),

� (8) Jád (Generosity),

� (9) Bahá (Splendor),

� (10) Hubb (Love),

� (11) Bahháj (Delightful),

� (12) Javáb (Answer),

� (13) Ahad (Single),

� (14) Vahháb (Bountiful),

� (15) Vidád (Affection),

� (16) Badí (Beginning),

� (17) Bahí (Luminous),

� (18) Abhá (Most Luminous), and

� (19) Váhid (Unity).

Nineteen cycles of the Váhid constitute a period called a Kull-i-Shay.

Holidays: Holidays in the Bahá’i Calendar are:

� Naw-Rúz (New year) (1 Bahá),

� Ridván–First Day (13 Jalál),

� Ridván–Ninth Day (2 Jamál),

� Ridván–Twelfth Day (5 Jamál),

� The Báb’s Declaration of His Mission (7 ’Azamat),

� Passing of Bahá’u’lláh (13 ’Azamat),

� Martyrdom of the Báb (16 Rahmat),

� Birth of the Báb (5 ’Ilm), and

� Birth of Bahá’u’lláh (9 Qudrat).

Balinese Calendar - Pawukon

Other Names: Also called the Pawukon Calendar.

Origin: The Pawukon Calendar is indigenous to the Balinese; it may be rooted in the ancient rice-growing cycle on Bali.

Mathematics: 6×35=210

New Year: The new year is referred to as Galungan.

Years: Years are 210 days long.

Months: For each year of the Pawukon Calendar there are 6 months, each of which is divided into 35 days.

Other Divisions: Each month is divided into shorter cycles, called weeks, which run concurrently. The most important of these are the 3-day, 5-day, and 7-day weeks.

Balinese Calendar - Sasih

Other Names: Also called the Sasih Cycle.

Origin: The Sasih Cycle is a 12 lunar month calendar system.

New Year: The new year is referred to as Nyepi.

Months: Each month begins the day after a new moon.

Days: The beginning of the month is tilem; the middle of each month (full moon) is purnama.

Byzantine Calendar

Correlation to Gregorian: Year 7505 of the Byzantine Calendar began on NS September 14, 1996 CE.

Calendar of the Martyrs (See Coptic Calendar)

Calendar Round (See Mayan Calendar)

Chinese Calendar

Other Names: Also called the Japanese Calendar (except that the Japanese Calendar counts its years differently).

Origin: The Chinese Calendar has its roots in the middle years of the Shang dynasty (c.1300 BCE), when the Chinese began using a cyclical system to count days.

Method: Lunisolar.

Years: An ordinary year of 12 months is between 353 and 355 days (inclusive); a leap year of thirteen months is between 383 and 385 days (inclusive). Various sets of rules exist for calculating the Chinese Calendar (because the calendar is based on the false assumption that the sun's motion is uniform, and because some calculations are based on mean or simplified sun and moon motions). The rules used by Purple Mountain Observatory are as follows: (1) The first day of the month is the day on which the new moon occurs. (2) An ordinary year has twelve lunar months; a leap year has thirteen lunar months. (3) The Winter Solstice (Principal Term 11) always falls in Month 11. (4) In a leap year, a month in which there is no Principal Term is the intercalary month; it is assigned the number of the preceding month, with the further designation of intercalary; if two months of a leap year contain no Principal Term, only the first such month after the Winter Solstice is considered intercalary. (5) Calculations are based on the meridian 120° East.

Years are also counted by succession within eras as proclaimed by emperors, or by the installation of the current civil government. The accession of an emperor begins a new era, but the emperor (or current government) can also establish a new era at any point within the reign. The Japanese Calendar uses this system of eras for counting years, but the eras are different, as they are declared by Japanese emperors.

Months: Months are numbered from 1 to 12 and begin on the date of the astronomical New Moon (conjunction). An intercalary month takes the number of the previous month, but is designated to be intercalary.

Days: Days run from midnight to midnight.

Other Divisions: The tropical year is marked by 24 Solar Terms, in 15° segments of solar longitude.

These Solar Terms are further divided into alternating Sectional Terms (Jieqi) and Principal Terms

(Zhongqi). These terms are as follows (S indicates Sectional; P indicates Principal) (Principal Terms are followed with an indication of how many days they last):

� (S-1) Lichun (Beginning of Spring) (315°) (~NS February 4),

� (P-1) Yushui (Rain Water) (330°) (~NS February 19) (29.8 days),

� (S-2) Jingzhe (Waking of Insects) (345°) (~NS March 6),

� (P-2) Chunfen (Spring Equinox) (0°) (~NS March 21) (30.2 days),

� (S-3) Qingming (Pure Brightness) (15°) (~NS April 5),

� (P-3) Guyu (Grain Rain) (30°) (~NS April 20) (30.7 days),

� (S-4) Lixia (Beginning of Summer) (45°) (~NS May 6),

� (P-4) Xiaoman (Grain Full) (60°) (~NS May 21) (31.2 days),

� (S-5) Mangzhong (Grain in Ear) (75°) (~NS June 6),

� (P-5) Xiazhi (Summer Solstice) (90°) (~NS June 22) (31.4 days),

� (S-6) Xiaoshu (Slight Heat) (105°) (~NS July 7),

� (P-6) Dashu (Great Heat) (120°) (~NS July 23) (31.4 days),

� (S-7) Liqiu (Beginning of Autumn) (135°) (~NS August 8),

� (P-7) Chushu (Limit of Heat) (150°) (~NS August 23) (31.1 days),

� (S-8) Bailu (White Dew) (165°) (~NS September 8),

� (P-8) Qiufen (Autumnal Equinox) (180°) (~NS September 23) (30.7 days),

� (S-9) Hanlu (Cold Dew) (195°) (~NS October 8),

� (P-9) Shuangjiang (Descent of Frost)

(210°) (~NS October 24) (30.1 days),

� (S-10) Lidong (Beginning of Winter) (225°) (~NS November 8),

� (P-10) Xiaoxue (Slight Snow) (240°) (~NS November 22) (29.7 days),

� (S-11) Daxue (Great Snow) (255°) (~NS December 7),

� (P-11) Dongzhi (Winter Solstice) (270°) (~NS December 22) (29.5 days),

� (S-12) Xiaohan (Slight Cold) (285°) (~NS January 6), and

� (P-12) Dahan (Great Cold) (300°) (~NS January 20) (29.5 days),

Intercalary/Leap System: The years are based on solar longitude, and a leap year is any year in which thirteen rather than twelve lunar months begin.

Correlation to Gregorian: The Chinese year 4695 began at sunset on NS February 7, 1997 (this would seem to reflect a system of counting years independent of that by counting from the accession of the

emperor or civil government). The current cycle of years (jia-zi, see below) began on NS February 2, 1984 CE.

Other Cycles: The Chinese Calendar follows a 60-year cycle, pairing the names of the Celestial Stems

and the Earthly Branches. The Celestial Stems, the names for which have no English translation, are:

� (1) jia,

� (2) yi, � (3) bing,

� (4) ding,

� (5) wu,

� (6) ji, � (7) geng,

� (8) xin,

� (9) ren, and

� (10) gui.

The Earthly Branches are:

� (1) zi (rat),

� (2) chou (ox),

� (3) yin (tiger),

� (4) mao (hare),

� (5) chen (dragon),

� (6) si (snake),

� (7) wu (horse),

� (8) wei (sheep),

� (9) shen (monkey),

� (10) you (fowl),

� (11) xu (dog), and

� (12) hai (pig).

They are paired together, cycling independently, as follows:

� (1) jia-zi, � (2) yi-chou,

� (3) bing-yin,

� (4) ding-mao,

� (5) wu-chen,

� (6) ji-si, � (7) geng-wu,

� (8) xin-wei, � (9) ren-shen,

� (10) gui-you,

� (11) jia-xu,

� (12) yi-hai, � (13) bing-zi, � (14) ding-chou,

� (15) wu-yin,

� (16) ji-mao,

� (17) geng-chen,

� (18) xin-si, � (19) ren-wu,

� (20) gui-wei, � (21) jia-shen,

� (22) yi-you,

� (23) bing-xu,

� (24) ding-hai, � (25) wu-zi, � (26) ji-chou,

� (27) geng-yin,

� (28) xin-mao,

� (29) ren-chen,

� (30) gui-si, � (31) jia-wu,

� (32) yi-wei, � (33) bing-shen,

� (34) ding-you,

� (35) wu-xu,

� (36) ji-hai, � (37) geng-zi, � (38) xin-chou,

� (39) ren-yin,

� (40) gui-mao,

� (41) jia-chen,

� (42) yi-si, � (43) bing-wu,

� (44) ding-wei, � (45) wu-shen,

� (46) ji-you,

� (47) geng-xu,

� (48) xin-hai, � (49) ren-zi, � (50) gui-chou,

� (51) jia-yin,

� (52) yi-mao,

� (53) bing-chen,

� (54) ding-si, � (55) wu-wu,

� (56) ji-wei, � (57) geng-shen,

� (58) xin-you,

� (59) ren-xu, and

� (60) gui-hai.

The current cycle began (jia-zi) on NS February 2, 1984 CE. A day count, using the same terms, has fallen into disuse, but this day of NS February 2, 1984 CE corresponded to the third day (bing-yin) of the cycle.

Christian Calendar (See Gregorian Calendar)

Coptic Calendar

Other Names: Also called the Calendar of the Martyrs.

Origin: Identical to the Ethiopian Calendar, except that the names are different (See Ethiopian Calendar).

Method: Solar.

Mathematics: 30×12+5=365 (common year) 30×12+6=366 (leap year)

New Year: The new year begins on NS September 11 (or on NS September 12 in Coptic Calendar years that follow Coptic Calendar leap years).

Months: Each month of the Coptic Calendar has 30 days. The months are:

� Thouot, � Paopi, � Athor, � Khoiak,

� Tobi, � Mekhir, � Famenot, � Farmout, � Pakhons,

� Paony,

� Epep,

� Mesori, and

� Nasie (period of 5 days, or 6 days in leap years).

Days: Days begin at sunrise; in contrast to the hours of the Gregorian Calendar, sunrise is always considered to be 1:00 by the Coptic Calendar.

Conformity to Solar Year: To bring the calendar to 365 days, the Coptic Calendar appends a month

called Nasie, lasting for 5 days in common years and 6 days in leap years.

Intercalary/Leap System: The Coptic Calendar adds a day to Nasie to track the leap years of the Gregorian Calendar. Leap years by the Coptic Calendar are those that end in a Gregorian Calendar year preceding a Gregorian Calendar leap year.

Correlation to Gregorian: The Coptic Calendar begins on NS September 11 (or on NS September 12 in Coptic Calendar years that follow Coptic Calendar leap years). The Coptic Calendar year 1989 began in 1996 CE.

Diocletian Calendar

Correlation to Gregorian: Year 1713 of the Diocletian Calendar began on NS September 11, 1996 CE.

Divine Calendar (See Mayan Calendar - Tzolkin)

Ethiopian Calendar

Other Names: Also called the Julian Calendar (not to be confused with the entirely different Julian Calendar from which the Gregorian Calendar was modified).

Origin: Identical to the Coptic Calendar, except that the names are different (See Coptic Calendar).

Method: Solar.

Mathematics: 30×12+5=365 (common year) 30×12+6=366 (leap year)

New Year: The new year begins on NS September 11 (or on NS September 12 in Ethiopian Calendar years that follow Ethiopian Calendar leap years).

Months: Each month of the Ethiopian Calendar has 30 days. The months are:

� Meskerem (or Maskerem),

� Tikemet (or Tikimit),

� Hidar, � Tahesas (or Tahsas),

� Tir, � Yekatit, � Megabit, � Miyaza (or Miazia),

� Ginbot (or Guenbot),

� Sene,

� Nehase (or Nahassie), and

� Pagume (or Pagumen) (period of 5 days, or 6 days in leap years).

Days: Days begin at sunrise; in contrast to the hours of the Gregorian Calendar, sunrise is always considered to be 1:00 by the Ethiopian Calendar.

Conformity to Solar Year: To bring the calendar to 365 days, the Ethiopian Calendar appends a

month called Pagume, lasting for 5 days in common years and 6 days in leap years.

Intercalary/Leap System: The Ethiopian Calendar adds a day to Pagume to track the leap years of the Gregorian Calendar. Leap years by the Ethiopian Calendar are those that end in a Gregorian Calendar year preceding a Gregorian Calendar leap year.

Correlation to Gregorian: The Ethiopian Calendar begins on NS September 11 (or on NS September 12 in Ethiopian Calendar years that follow Ethiopian Calendar leap years). The Ethiopian Calendar year 1989 began in 1996 CE.

Fasli Calendar (See Zoroastrian Calendar - Fasli)

French Republican Calendar (See Republican Calendar)

Friends Calendar (See Quaker Calendar)

Goddess Lunar Calendar

Origin: The Goddess Lunar Calendar was devised by Peter Meyer, and dates in this calendar are

followed with the abbreviation GLC. It is designed to stay tightly in synch with the moon’s phases over time (to five decimal places for several millennia, in fact), although there may be occasional brief fluctuations when the moon is "fast" or "slow."

Method: Lunar.

Mathematics: 30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30=738 (common year) 30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+29+30+30+30=739 (leap year)

Years: Years begin with 0. In that the Goddess Lunar Calendar year is more than twice as long as a solar year, dates in the Goddess Lunar Calendar will slowly move backward through the seasons, back to the original relation to the seasons in approximately 93.9 years. The base (zero) year of the Goddess Lunar Calendar was chosen with the considerations that it must (1) be sufficiently distant that most referenced dates are positive and (2) that it must maximize the number of new moons on the first of the month and the number of full moons on the night between the 14th and 15th of the month. Thereby the base Goddess Lunar Calendar date of Artemis 1, 0 GLC was chosen to be NS January 10, 4061 BCE.

Months: The 25 months of the Goddess Lunar Calendar are named after goddesses of the Greek, Hindu, Roman, Egyptian, Yoruba, Celtic, Phrygian, Maya, Aztec, Shinto, Chinese Buddhist, Indian Buddhist, German, And Sumerian cultures. The months alternate between 29 and 30 days, with odd-numbered months having 30 days and even-numbered months having 29 days. They are numbered 1 to 25 and also carry names which begin, in sequence, with the first 25 letters of the English alphabet:

� (1) Artemis (30 days),

� (2) Bast (29 days),

� (3) Cybele (30 days),

� (4) Durga (29 days),

� (5) Eris (30 days),

� (6) Freya (29 days),

� (7) Gaea (30 days),

� (8) Hathor (29 days),

� (9) Ix Chel (30 days),

� (10) Juno (29 days),

� (11) Kali (30 days),

� (12) Luna (29 days),

� (13) Maat (30 days),

� (14) Nisaba (29 days),

� (15) Oya (30 days),

� (16) Persephone (29 days),

� (17) Quan Yin (30 days),

� (18) Rhiannon (29 days),

� (19) Saraswati (30 days),

� (20) Tara (29 days),

� (21) Usha (30 days),

� (22) Venus (29 days),

� (23) Waka-Hiru-Me (30 days),

� (24) Xochiquetzal (29 days, or 30 days in leap years), and

� (25) Yemaya (30 days).

Days: Days of the week are the same as in the Gregorian Calendar:

� Sunday,

� Monday,

� Tuesday,

� Wednesday,

� Thursday,

� Friday, and

� Saturday.

Conformity to Solar Year: No attempt is made to conform to the solar year, and, in fact, the Goddess Lunar Calendar year is a little more that double a solar year.

Intercalary/Leap System: Leap years are years that are divisible by 4 or by 51. In a leap year, the 24th

month, Xochiquetzal, has an extra day. This was chosen because the Aztecs held a festival in honor of the goddess Xochiquetzal every eight years, and the duration of eight years by the Aztec Calendar (see Aztec Calendar – Tonalpohualli) approximately corresponds to the four years of the Goddess Lunar Calendar.

Correlation to Gregorian: The date NS January 1, 1997 CE corresponds to the Goddess Lunar Calendar date Bast 22, 2997 GLC (which can also be rendered as 2997-02-22 GLC).

Holidays: One holiday in the Goddess Lunar Calendar is:

� Xochiquetzal Festival (Xochiquetzal 30, which occurs only in leap years),

Grecian Calendar

Origin: The Grecian Calendar was based on the Metonic Cycle (see "Metonic Cycle" in the "Calendar Calculations" section). It showed that 235 lunar months made up almost exactly 19 solar years.

Method: Lunar.

Intercalary/Leap System: The Metonic Cycle required the intercalation of a 7 leap months over the course of the 19-year cycle; these were inserted in years 3, 5, 8, 11, 13, 16, and 19 of the cycle. Around

325 BCE, Callipus modified the calendar by applying the longer Callipic Cycle. Later Hipparchus

proposed the even longer Hipparchic Cycle. Neither the Callipic nor the Hipparchic systems, however, were widely used.

Correlation to Gregorian: Year 2308 of the Grecian Calendar began on NS September 14, 1996 CE or NS October 14, 1996 CE.

Gregorian Calendar

Other Names: Also Called the New Style Calendar, Christian Calendar.

Origin: The Gregorian Calendar is the most common modern calendar. It was a modification of the Julian Calendar, undertaken because the Julian Calendar year averaged 11 minutes and 14 seconds longer than the solar year, causing a discrepancy that accumulated over the centuries.

Both the Gregorian Calendar and the Julian Calendar date back to the presumed birth of Jesus Christ. Yet, because of calendar reform, they do not originate on the same date (and both beginning points differ from historical evidence as to the year of Jesus's birth). Additionally, the celebrated date of Jesus's birth is taken to be December 25 (although there is strong historical evidence against this), but neither calendar marks its New Year from this date (however, some communities using the Julian Calendar once did).

The Gregorian Calendar resulted from a decree from Pope Gregory XIII, dropping 10 days from the calendar and modifying the system of leap years to make the vernal equinox occur on March 21, as it had in 325 CE (the year of the First Council of Nicaea).

When the Gregorian Calendar was adopted in Great Britain in 1752, the discrepancy had increased to 11 days, and the correction had to reflect this: For British record keeping, the day after (OS) September 2, 1752 became (NS) September 14, 1752. The British also adopted January 1 as the day when a new year begins. Previously, in some areas, the new year began on March 1 or April 1.

Method: Solar. Twelve months of varying days to bring the calendar to 365 days (or 366 days in leap years).

Mathematics: 31+28+31+30+31+30+31+31+30+31+30+31=365 (common year) 31+29+31+30+31+30+31+31+30+31+30+31=366 (leap year)

New Year: The beginning of the year is January 1.

Years: In Christian religious contexts, dates according to the Gregorian Calendar are preceded by AD

(for "anno Domini," [the year of the Lord]) or followed by BC (for "before Christ"); in other contexts, the

dates are followed respectively with CE (for "Common [or Christian] Era") or BCE (for "Before the

Common [or Christian] Era"). In English, AD is often replaced - especially in speaking - with the phrase,

"The Year of Our Lord." In referring to centuries, AD and BC come after the reference (e.g., "the fourth century AD"). It is not unusual, although not strictly correct, to see years and dates followed, rather than

preceded, by AD.

Because the Julian Calendar uses the same AD/BC/CE/BCE designators as the Gregorian Calendar, various systems are employed for distinguishing between the two. Most commonly, Gregorian

Calendar dates are preceded by the abbreviation NS (New Style), and Julian Calendar dates are

preceded by the abbreviation OS (Old Style). Alternately dates in the Gregorian Calendar are distinguished from the Julian Calendar by dropping the designators altogether and using positive year

numbers for CE and negative year numbers for BCE; for example, the Gregorian Calendar dates NS October 13, 1914 CE and NS July 6, 45 BCE would be October 13, 1914, and July 6, -45 respectively.

It should also be noted that according to most reckoning systems, the Gregorian Calendar differs from the Julian Calendar insofar as it has a year 0.

Months: The months of the Gregorian Calendar are named differently in different languages. In English they are:

� January (31 days)

(named for Roman Calendar month Januarius [or Ianuarius], for Janus, god of beginnings and doorways),

� February (28 days, 29 days in leap years)

(named for Roman Calendar month Februarius, for Februa, feast of purification),

� March (31 days)

(named for Roman Calendar month Martius, for Mars),

� April (30 days)

(named for Roman Calendar month Aprilis [Romans considered the month sacred to Venus, and Aprilis may be from Venus's Greek equivalent, Aphrodite]),

� May (31 days)

(named for Roman Calendar month Maius, probably for Maia),

� June (30 days)

(named for Roman Calendar month Junius [or Iunius], for Juno),

� July (31 days)

(named for Roman Calendar month Julius [or Iulius], for Julius Caesar),

� August (31 days)

(named for Roman Calendar month Augustus, for the emperor Augustus),

� September (30 days)

(named for Roman Calendar month september, from septem, meaning seven, as this was the seventh month of the Roman Calendar),

� October (31 days)

(named for Roman Calendar month october, from octo, meaning eight, as this was the eighth month of the Roman Calendar),

� November (30 days)

(named for Roman Calendar month november, from nove, meaning nine, as this was the ninth month of the Roman Calendar), and

� December (31 days)

(named for Roman Calendar month december, from decem, meaning ten, as this was the tenth month of the Roman Calendar).

Several rhymes have been employed to remind which months have what number of days:

"Junius, Aprilis, Septémq; Nouemq; tricenos, Vnum plus reliqui, Februs tenet octo vicenos, At si bissextus fuerit superadditur vnus."

"Thirty dayes hath Nouember, Aprill, June, and September, February hath xxviii alone, And all the rest have xxxi."

"Thirty days hath September, April, June, and November, February has twenty-eight alone, All the rest have thirty-one; Excepting leap year,-that's the time When February's days are twenty-nine."

"Thirty days hath September, April, June, and November; All the rest have thirty-one, Excepting February alone, Which hath but twenty-eight, in fine, Till leap year gives it twenty-nine."

"Thirty days hath September, April, June, and November; All the rest have thirty-one, Except February alone, Which has twenty-eight days clear, And twenty-nine in each leap year."

Days: The Gregorian calendar follows a seven-day week that cycles independently of the months and years. The names of the days, in English, are:

� Sunday (named for the Sun),

� Monday (named for the Moon),

� Tuesday (named for Tiw, god of war),

� Wednesday (named for Woden),

� Thursday (named for Thor),

� Friday (named for Freya), and

� Saturday (named for Saturn).

In most settings, including virtually all religious calendars, Sunday is the first day. Some business settings will show Monday as the first day. Days begin at midnight.

The Gregorian Calendar improved on the Julian Calendar by establishing the way days are counted in the month - from 1 up to 28, 29, 30, or 31 (depending on the month). The Julian Calendar had used a more complicated system of counting down to one of three divisions in each month (see Julian Calendar).

Common systems for writing a date (for example, the fifth day of April of the year 1996) include the following: 4/5/1996, 5/4/1996, 1996/4/5, 5.4.1996, and 05APR1996; in each of these, the year is sometimes truncated to the last two digits. The international standard for writing dates is year-month-day, and this date would be written as 19960405; the hyphens can be omitted (19960405) and the year can be truncated (960405).

Other Divisions: Days are divided into 24 hours, which are divided into 60 minutes, which are divided into 60 seconds. In the U.S., hours are divided into two 12-hour blocks, with those after midnight and

before noon (not inclusive) designated as A.M. (or ante meridiem) - for example, 3:58 A.M. - and those

after noon and before midnight (not inclusive) designated as P.M. (or post meridiem). Noon is designated

12:00 N. and midnight is designated 12:00 M. (Where A.M. and P.M. are the only choices, such as in

setting digital clocks, noon is considered P.M. and midnight is considered A.M.) These hours flow as follows over the course of a day:

� 12:00 M. (0:00 or 24:00) (preceded by 11:59:59 P.M.) (followed by 12:00:01 A.M.),

� 1:00 A.M. (1:00),

� 2:00 A.M. (2:00),

� 3:00 A.M. (3:00),

� 4:00 A.M. (4:00),

� 5:00 A.M. (5:00),

� 6:00 A.M. (6:00),

� 7:00 A.M. (7:00),

� 8:00 A.M. (8:00),

� 9:00 A.M. (9:00),

� 10:00 A.M. (10:00),

� 11:00 A.M. (10:00),

� 12:00 N. (12:00) (preceded by 11:59:59 A.M.) (followed by 12:00:01 P.M.),

� 1:00 P.M. (13:00),

� 2:00 P.M. (14:00),

� 3:00 P.M. (15:00),

� 4:00 P.M. (16:00),

� 5:00 P.M. (17:00),

� 6:00 P.M. (18:00),

� 7:00 P.M. (19:00),

� 8:00 P.M. (20:00),

� 9:00 P.M. (21:00),

� 10:00 P.M. (22:00), and

� 11:00 P.M. (23:00).

In other parts of the world - and in the U.S. military - a 24-hour clock is used, running from 0:00 at midnight to 23:59 (or from 0:01 at midnight to 24:00, depending on the counting system). In U.S. military settings, the colon is omitted and the hours always use two digits, for example 0358 (spoken as "oh-three-fifty-eight hours") or 0700 (spoken as "oh-seven-hundred hours"). February 4 at 24:00 and February 5 at 0:00 refer to the same time; 0:00, however, is the preferred representation of midnight.

Appending a Z to the time indicates that it refers to the Universal Time (UTC) at Greenwich in London,

England. "Z" refers to the "zero meridian," which passes through Greenwich, and references to it are often spoken as "Zulu time" ("Zulu" being the designation for the letter Z in the NATO spoken alphabet). For example, 17:30Z is spoken as "Seventeen, thirty Zulu time," and refers to that time of day in Greenwich.

Intercalary/Leap System: The Gregorian Calendar retained the Julian Calendar's system of adding a day to February in every year evenly divisible by 4. But to prevent further drift, the Gregorian Calendar instituted a system whereby century years divisible evenly by 400 should be leap years and that all other century years should be common years. (Thus, 1600 was a leap year, but 1700 and 1800 were common years.)

Other Cycles: A cycle of 10 years is called a decade; a cycle of 100 years is called a century; a cycle of

1000 years is called a millennium. A generation refers to an indefinite period (but typically viewed as ~30 years) that corresponds to the time between the birth of parents and the birth(s) of their offspring. Also, because calendar months are longer (usually) than the moon cycle, a second full moon during a calendar

month is referred to as a blue moon.

Holidays: Insofar as the Gregorian Calendar is in worldwide usage, almost every political division has its own set of holidays according to it. Additionally, as it is used by virtually all Christian sects (except

the Orthodox churches), they too each have sets of holidays and saint's days on this calendar. To document all these would be far beyond the scope of this document. However, some basic Christian holidays (the Gregorian Calendar having been created as a timekeeping mechanism for Christianity) are:

� Septuagesema (63 days before NS Easter),

� Quinquagesema (49 days before NS Easter),

� Ash Wednesday (46 days before NS Easter),

� Palm Sunday (7 days before NS Easter),

� Good Friday (2 days before NS Easter),

� Easter (first Sunday after full moon that occurs on or after the vernal equinox, see below),

� Rogation Sunday (35 days after NS Easter),

� Ascension (39 days after NS Easter),

� Pentecost (49 days after NS Easter),

� Trinity Sunday (56 days after NS Easter),

� Corpus Christi (60 days after NS Easter),

� Solemnity of Mary (NS January 1),

� Epiphany (NS January 6),

� Presentation of the Lord (NS February 2),

� Annunciation (NS March 25),

� Transfiguration of the Lord (NS August 6),

� Assumption of Mary (NS August 15),

� Birth of Virgin Mary (NS September 8),

� Celebration of the Holy Cross (NS September 14),

� Mass of the Archangels (NS September 29),

� All Saints' Day (NS November 1),

� All Souls' Day (NS November 2), and

� Christmas (NS December 25).

For the purposes of computing Easter, a convention has been established of assuming the vernal equinox to be on March 21, rather that the actual moment of the equinox; similarly, this full moon (often referred

to as the Pascal Full Moon) is identified using the Metonic Cycle (see "Metonic Cycle" under the "Calendar Calculations" section) rather than astronomical calculations. Some systems for calculating Easter (with varying degrees of accuracy) are as follows:

Comparing Epacts and Dominical Letters:

For the current year, find the Epact (see "Epact" in "Calendar Calculations" section) and the Dominical Letter (see "Dominical Letter" in "Calendar Calculations" section). Then compare the results with the following chart:

Epact Dominical Letter

A B C D E F G

0 16 17 18 19 20 14 15

1 16 17 18 19 13 14 15

2 16 17 18 12 13 14 15

3 16 17 11 12 13 14 15

4 16 10 11 12 13 14 15

5 9 10 11 12 13 14 15

6 9 10 11 12 13 14 8

Dates followed by the cross "†" are in March; the rest are in April. The Epact "25*" indicates a different set of calculations for certain years, including 1916, 1935, 1954, 1973, and 1992.

Oudin's Algorithm (works with dates after 1583 CE):

Take the integer of all results.

Century = Year/100

G = Year MOD 19

K = (Century - 17)/25

I = (Century - Century/4 - (Century - K) / 3 + 19 × G + 15) MOD 30

I = I - (I/28) × (1 - (I/28) × (29/(I + 1)) × ((21 - G)/11))

J = (Year + Year/4 + I + 2 - Century + Century/4) MOD 7

7 9 10 11 12 13 7 8

8 9 10 11 12 6 7 8

9 9 10 11 5 6 7 8

10 9 10 4 5 6 7 8

11 9 3 4 5 6 7 8

12 2 3 4 5 6 7 8

13 2 3 4 5 6 7 1

14 2 3 4 5 6 31† 1

15 2 3 4 5 30† 31† 1

16 2 3 4 29† 30† 31† 1

17 2 3 28† 29† 30† 31† 1

18 2 27† 28† 29† 30† 31† 1

19 26† 27† 28† 29† 30† 31† 1

20 26† 27† 28† 29† 30† 31† 25†

21 26† 27† 28† 29† 30† 24† 25†

22 26† 27† 28† 29† 23† 24† 25†

23 26† 27† 28† 22† 23† 24† 25†

24 23 24 25 19 20 21 22

25 23 24 25 19 20 21 22

25* 23 24 18 19 20 21 22

26 23 24 18 19 20 21 22

27 23 17 18 19 20 21 22

28 16 17 18 19 20 21 22

29 16 17 18 19 20 21 15

L = I - J

Easter Month = 3 + (L + 40) / 44

Easter Day = L + 28 - 31 × (Easter Month / 4)

Carter's Algorithm (works with dates between 1900 CE and 2099 CE):

Take the integer of all results.

B = 225 - 11 (Year MOD 19)

D = ((B - 21) MOD 30) + 21

If D > 48, subtract 1 from it.

E = (Year + (Year/4) + D + 1 MOD 7

Q = D + 7 - E

If Q < 32, Easter is in March on Q day.

Otherwise, Easter is in April on Q-31 day.

John Conway's Algorithm:

G = Golden Number (see "Metonic Cycle" in "Calendar Calculations" section)

H = Century number (for 1996, H = 19).

C = INT(H/4) + INT(8(H + 11) / 25) - H

S = (11G + C) MOD 30

The Pascal Full Moon is April 19 - S days.

If this renders a date of April 19, the Pascal Full Moon is April 18.

If this renders a date of April 18 and G 12, the Pascal Full Moon is April 17.

Easter is the Sunday after, not on, the Pascal Full Moon.

Haab Calendar (See Mayan Calendar - Haab)

Hebrew Calendar (See Jewish Calendar)

Hegira Calendar (See Islamic Calendar)

Hindu Calendar - Civil

Other Names: Also called the Indian Calendar, Saka Calendar.

Origin: Established in 1957 CE by the Calendar Reform Committee, the Hindu Civil Calendar counts its years from the vernal equinox of 79 CE, and refers to itself as the Saka Era.

Method: Solar.

Mathematics: 30+31+31+31+31+31+30+30+30+30+30+30=365 (common year) 31+31+31+31+31+31+30+30+30+30+30+30=366 (leap year)

New Year: The New Year is on Caitra 1.

Years: Years in the Hindu Civil Calendar are preceded by the words "Saka Era."

Months: The months of the Hindu Civil Calendar are:

� Caitra (30 days) (NS March 22) (or 31 days and starting on NS March 21 in leap years),

� Vaisakha (31 days) (NS April 21),

� Jyaistha (31 days) (NS May 22),

� Asadha (31 days) (NS June 22),

� Sravana (31 days) (NS July 23),

� Bhadra (31 days) (NS August 23),

� Asvina (30 days) (NS September 23),

� Kartika (30 days) (NS October 23),

� Agrahayana (30 days) (NS November 22),

� Pausa (30 days) (NS December 22),

� Magha (30 days) (NS January 21), and

� Phalguna (30 days) (NS February 20).

Days: Days run from sunrise to sunrise.

Intercalary/Leap System: Leap years conform to leap years of the Gregorian Calendar.

Correlation to Gregorian: Saka Era 1918, Caitra 1 fell on NS March 21, 1996 CE.

Hindu Calendar - Lunar

Other Names: Also called the Indian Calendar, Indian Religious Calendar.

Origin: Hindu calendar calculations are extremely complex due to the age and diversity of the Hindu culture as well as its early and long-standing contacts with outside cultures. The Surya Siddhanta has influenced Hindu calendar calculation from its creation in the 4th century CE to the present.

Method: Lunisolar.

Years: Various starting points are recognized in the Hindu Calendar, and, to complicate matters, each can be reckoned as having started in year 0 (counting elapsed years) or year 1 (counting current years). A

common epoch is the Kali Yuga (Iron Age), which began on NS January 23, 3101 BCE (at the time of the most recent conjunction of all the visible planets); dates for this epoch are followed by the abbreviation

KY.

Months: There is significant variation in how the months are reckoned in the Lunar Hindu Calendar: Different systems begin with different months. Additionally, the amânta system of calculating between

new moons is common in southern India while the pûrnimânta system of calculating between full moons is prevalent in northern India. The months of the Lunar Hindu Calendar are:

� Chaitra (or Caitra) (353°15') (30.3 days) (~NS March 14),

� Vaisakha (23°15') (30.9 days) (~NS April 13),

� Jyaishtha (or Jyestha) (53°15') (31.3 days) (~NS May 14),

� Ashadha (or Asadha) (83°15') (31.5 days) (~NS June 14),

� Sravana (113°15') (31.4 days) (~NS July 16),

� Bhadrapada (143°15') (31.0 days) (~NS August 16),

� Asvina (173°15') (30.5 days) (~NS September 16),

� Karttika (or Kartika) (203°15') (30.0 days) (~NS October 17),

� Margasira (or Margasirsa) (233°15') (29.6 days) (~NS November 16),

� Pausha (or Pausa) (263°15') (29.4 days) (~NS December 15),

� Magha (293°15') (29.5 days) (~NS January 14), and

� Phalguna (or Phalgura) (323°15') (29.9 days) (~NS February 12).

The months are named after the solar month in which the new moon begins. On rare occasions a short solar month will not contain a new moon, and the name of that month is dropped from the calendar for that year; this will, however, result in two new moons in a later month, so the calendar will remain at 12

months. These lost months are referred to as ksaya ("decayed") months. As few as 19 years, and as many as 141 years, may pass between ksaya months.

Days: Although solar days are used to establish their number, months of the Lunar Hindu Calendar are

divided not into days, but rather into 30 tithis. Each tithi is described as the time required for the moon to increase by 12° over the longitude of the sun; they may last for between ~20 hours and ~27 hours. The

first fifteen tithis are referred to as suddha (or Sukla) ("bright" or "waxing") and are counted 1 to 15, while

the last fifteen are referred to as bahula (or Krsna) ("dark" or "waning") and are also counted 1 to 15. The date of the lunar month corresponds to the tithi at sunrise - and there are lost dates when a tithi begins and ends between sunrises as well as long dates when the date number is carried over to the next day. The Calendar Reform Committee established that solar days run from sunrise to sunrise.

Intercalary/Leap System: A lunar month is intercalated whenever two new moons occur within one

sign of the zodiac. The two months take the same name, but the first is called adhika ("added") while the

second is called nija ("regular").

Hindu Calendar - Solar

Other Names: Also called the Indian Calendar.

Origin: The Solar Hindu Calendar is used primarily in Southern India, with the Lunar Hindu Calendar being used predominantly in other areas.

Method: Solar. Current Hindu calendars base themselves on the true time of the sun's entrance into the signs of the zodiac; historically, however, mean times were used instead.

New Year: The new year is called Mesha samkranti. It is the date of the first sunrise after the sun enters

Mesha.

Years: Various starting points are recognized in the Hindu Calendar, and, to complicate matters, each can be reckoned as having started in year 0 (counting elapsed years) or year 1 (counting current years). A

common epoch is the Kali Yuga (Iron Age), which began on NS January 23, 3101 BCE (at the time of the most recent conjunction of all the visible planets); dates for this epoch are followed by the abbreviation

KY. While most calendars use the tropical year (the time it takes the sun to circle back to the same apparent position), the Hindu Calendar counts sidereal years (the time it takes the sun to circle back to its same celestial longitude).

Months: Months begin on the day of the first sunrise after the sun enters their sign, hence the lengths of the months vary from year to year. The months of the Solar Hindu Calendar are:

� Mesha (Aries),

� Vrshabha (Taurus),

� Mithuna (Gemini),

� Karka (Cancer),

� Simha (Leo),

� Kanya (Virgo),

� Tula (Libra),

� Vrischika (Scorpio),

� Dhanus (Sagittarius),

� Makara (Capricorn),

� Kumbha (Aquarius), and

� Mina (Pisces).

Days: The Kali Yuga era began at midnight, indicating that days ran in that calculation from midnight to midnight. The Calendar Reform Committee indicated that solar days run from sunrise to sunrise.

Inca Calendar

Origin: While some people are of the opinion that the Incas had no calendar, most believe that an Inca Calendar existed, based on the sun and the moon.

Method: Lunisolar?

Months: Work was organized on the basis of a nine-day week, and three of these weeks would have made up 27 days - approximately the time of the lunar cycle.

Other Cycles: With every third year having 13 moons instead of the regular 12, a cycle of 37 moons was recognized. Twenty of these cycles made a period of 60 years.

Indian Calendar (See Hindu Calendar)

Indian Religious Calendar (See Hindu Calendar - Lunar)

Indonesian Calendar

Other Names: Also called the Javanese Calendar.

Origin: The Javanese Calendar was decreed by Sultan Agung Hanyokrokosumo in 1663. It dates from the Gregorian Calendar year 78.

Months: The Months of the Indonesian Calendar are:

� Ruwah,

� Pasa,

� Sawal, � Hapit, � Besar, � Sura,

� Sapar, � Mulud,

� Bakdomulud,

� Jumadilawal, � Jumadilakhir, and

� Rejeb.

Days: Days begin "when fowls begin to sleep, a moment after sunset."

Correlation to Gregorian: The year 1918 by the Indonesian Calendar corresponds to the year 1996 CE.

Other Cycles: The Windu is an eight-year cycle of years, the names for which are:

� Alip,

� Ehe (leap year),

� Jimawal, � Je (leap year),

� Dal, � Be,

� Wawu, and

� Jimakir (leap year),

International Fixed Calendar

Other Names: Also Called the Thirteen Month Calendar.

Origin: The International Fixed Calendar is a proposed modification of the Gregorian Calendar. Half-years contain exactly 26 seven-day weeks and quarter-years exactly 13 weeks.

Method: Solar. Thirteen months of twenty-eight days each, with a Year Day to bring the calendar to 365

days, and a Leap Day to bring it to 366 days in leap years.

Mathematics: 13×28+1=365 (common year) 13×28+1+1=366 (leap year)

New Year: New Year's Day is January 1.

Months: The International Fixed Calendar is divided into 13 months of 28 days each. The months are

essentially the same as Gregorian Calendar months, except that an additional month, Sol, is added

between June and July:

� January,

� February,

� March,

� April, � May,

� June,

� Sol, � July,

� August, � September, � October, � November, and

� December.

Other thirteen-month systems have been proposed that are identical to this except that the thirteenth

month, the Year Day, and the Leap Day may have different names, and are sometimes placed elsewhere in relation to the other 12 months.

Days: The International Fixed Calendar follows the seven day week. The names of the days are the same as in the Gregorian Calendar, but Sundays always occur on the 1st, 8th, 15th, and 22nd of each

month. To bring the calendar up to 365 days, a Year Day is appended after December 28, this Year Day belonging to no week or month. Days run from midnight to midnight.

Other Divisions: Identical to the Gregorian Calendar.

Intercalary/Leap System: In leap years (which correspond to Gregorian Calendar leap years) an extra

Leap Day, belonging to no week or month, is added after June 28.

Correlation to Gregorian: January 1 by the International Fixed Calendar is the same as NS January 1. The year numbers are the same as in the Gregorian Calendar.

Islamic Calendar

Other Names: Also called the Muslim Calendar, Hegira Calendar.

Origin: The Islamic Calendar begins at the Hegira (NS July 16, 622 CE), when Mohammed fled from Mecca to Medina.

Method: Lunar.

Mathematics: 30+29+30+29+30+29+30+29+30+29+30+29=354 (common year) 30+29+30+29+30+29+30+29+30+29+30+30=355 (leap year)

New Year: The first day of the year is Muharram 1. Due to the fact that at 354 days (or 355 days in leap years) the Islamic year is shorter than the solar year, this date drifts backward through the seasons over the years.

Years: Years in the Islamic Calendar are preceded by the abbreviation AH, from the Latin anno Hejirae (the year of the Hegira).

Months: The months begin at the appearance of the crescent moon after the new moon. They are:

� Muharram (or Moharram) (30 days),

� Safar (29 days),

� Rabi I (or Rabi'a I) (30 days),

� Rabi II (or Rabi'a II) (29 days),

� Jumada I (30 days),

� Jumada II (29 days),

� Rajab (30 days),

� Sha'ban (or Shaban) (29 days),

� Ramadan (30 days) (month of fasting from sunrise to sunset),

� Shawwal (29 days),

� Dhu al-Qada (or Dhu 'I-Qa'da, or Dhu al-Q'adah, or Dhu al-Qa'dah, or Dhu'l-Qa'dah) (30 days), and

� Dhu al-Hijjah (or Dhu 'I-hijjah, or Dhu'I-Hijja) (29 days, or 30 days during leap years).

Days: Days run from sunset to sunset.

Intercalary/Leap System: While this calendar makes no effort to track the solar year, it does include a leap system in which a 30-year cycle includes leap years in the 2nd, 5th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 26th, and 29th years. This system is designed to ensure correlation between the first day of the month and the new moon. The most recent 30-year cycle began with AH 1411 on the night before NS July 24, 1990 CE.

Correlation to Gregorian: The Islamic year AH 1413 began on NS July 2, 1992 CE.

The Islamic Calendar date corresponding to a Gregorian Calendar date can be computed by the following formula:

IY = Islamic Year + (Islamic Days Elapsed/Days in Islamic Year)

GY = (IY × 0.970224) + 621.5774

GD = (GY - INT(GY)) × Days in Gregorian Year

GY = Gregorian Year

GD = Days Elapsed in Gregorian Year

It should be noted, however, that any conversion or prediction system for the Islamic calendar, including the leap system described above, risks an up-to-two day inaccuracy with the calendar in use in a particular location; this is because some Muslims use differing conversion systems, and because a predominant belief is that only the first visual (human) sighting of the crescent moon (which, of course, is subject to astronomical and atmospheric conditions) can mark the beginning of the month. Among those

holding this latter view, some base the new month on the local sighting (Ikhtilaf al-Matale') while others

base it on a sighting anywhere in the Muslim world (Ittehad al-Matale'); both views are considered valid.

Holidays: Recognition of holidays is not uniform across the Islamic world. Widely recognized holidays in the Islamic Calendar include:

� New Year (Muharram 1),

� Ashura (Muharram 10),

� Mulad-al-Nabi (Rabi I 12),

� Shab-e-Mi'raj (Rajab 26),

� Shab-e-Bara't (Sha'ban 15),

� Ramadan (Ramadan 1),

� Shab-e Qadr (Ramadan 27),

� Id-al-Fitr (Shawwal 1), and

� Id-al-Adha (Dhu-al-Hijjah 10).

ISO Calendar

Origin: ISO stands for International Standards Organization. The ISO Calendar is based on the

Gregorian Calendar, except that it renders dates as days of calendar weeks. Section 3.17 of the ISO

standard defines calendar week as,

A seven day period within a calendar year, starting on a Monday and identified by its ordinal number within the year; the first calendar week of the year is the one that includes the first Thursday of that year. In the Gregorian calendar, this is equivalent to the week which includes 4 January.

Dates are rendered in the format, 1996-W43-4. This indicates that it is the 4th day (Thursday) of the 43rd week of 1996.

Method: Solar.

Mathematics: 52×7=364 53×7=371

New Year: Though the calendar corresponds to the Gregorian Calendar, W01-1 can occur from NS December 29 to NS January 4.

Years: Years are the same as the Gregorian Calendar, with some variation at the beginning/end of years since the new year dates are not identical.

Weeks: The first week of the year is the one which, according to the Gregorian Calendar, contains the first Thursday.

Days: Weeks start on Mondays, and the days are numbered starting with Monday:

� 1 (Monday),

� 2 (Tuesday),

� 3 (Wednesday),

� 4 (Thursday),

� 5 (Friday),

� 6 (Saturday), and

� 7 (Sunday).

Conformity to Solar Year: The ISO Calendar conforms to the Gregorian Calendar, which conforms to the solar year. This results in the ISO Calendar occasionally having 53 weeks instead of 52.

Intercalary/Leap System: The ISO Calendar conforms to the Gregorian Calendar. It does not have a leap year structure of its own, but its occasional jump to 53 weeks makes it possible for it to track the years of the Gregorian Calendar.

Correlation to Gregorian: Year numbers are the same. The ISO Calendar is based on the Gregorian Calendar and cannot be calculated independently of it.

Jalaali Calendar

Other Names: Also called the Persian Calendar.

Origin: The Jalaali Calendar is official in Iran and surrounding areas, and was named after Jalaal-ol-Din Malek-shaah-e Saljuqi (by Omar Khayyam, who reworked the calendar in the fifth century AH).

Method: Solar. Twelve months of varying days to bring the calendar to 365 days (or 366 days in leap years).

Mathematics: 31+31+31+31+31+31+30+30+30+30+30+29=365 (common year) 31+31+31+31+31+31+30+30+30+30+30+30=366 (leap year)

New Year: The Jalaali new year (tahvil-e saal) comes at the point when the sun appears to cross the equator from the southern to the northern hemisphere, as viewed from the center of the earth. If this is before midday in Tehran, Iran, the new year is that day; otherwise it is the following day.

Months: The months of the Jalaali Calendar are:

� farvardin (31 days),

� ordibehesht (31 days),

� khordad (31 days),

� tir (31 days),

� mordad (31 days),

� shahrivar (31 days),

� mehr (30 days),

� Aban (30 days),

� Azar (30 days),

� day (30 days),

� bahman (30 days), and

� esfand (29 days, or 30 days during leap years).

Days: Days in the Jalaali Calendar are:

� shanb (Saturday),

� yeksh (Sunday),

� dosh (Monday),

� sehsh (Tuesday),

� chehar (Wednesday),

� panj (Thursday), and

� jomeh (Friday).

Intercalary/Leap System: The system described above results in eight leap years during a cycle of (typically) 33 years; currently leap years are those with a remainder - after dividing by 33 - of 1, 5, 9, 13, 17, 22, 26, and 30. Because this system isn't mathematically prescribed, however, the table of leap years must occasionally be pushed one step back.

Correlation to Gregorian: The Jalaali Calendar year 1374 began (1 farvardin 1374) on NS March 21, 1995 CE.

Japanese Calendar

Correlation to Gregorian: Year 2656 of the Japanese Calendar began on NS January 1, 1996 CE.

Japanese Calendar (Chinese) (See Chinese Calendar)

Javanese Calendar (See Indonesian Calendar)

Jewish Calendar

Other Names: Also called the Hebrew Calendar.

Origin: The Jewish Calendar begins at the "Creation," which Judaism calculates to have occurred 3,760 years before the Christian era.

Method: Lunisolar. The common year is between 353 and 355 days; in leap years an intercalary month is added to make the calendar track with the solar year, bringing the year to 383 to 385 days. A regular

(kesidrah) year has 354 or 384 days, with 29 days in the month of Heshvan and 30 days in the month of

Kislev. Pursuant to various delays (dehiyyot [singular is dehiyyah]) which are described below, the year can

become a "complete" (shelemah) year (355 days or 385 days) with 30 days in both Heshvan and Kislev or

a "deficient" (haser) year (353 days or 383 days) with 29 days in Heshvan and Kislev.

Mathematics: 30+29+30+29+30+29+30+29+29+29+30+29=353 (deficient common year) 30+29+30+29+30+29+30+29+30+29+30+29=354 (regular common year) 30+29+30+29+30+29+30+30+30+29+30+29=355 (complete common year) 30+29+30+29+30+29+30+29+29+29+30+30+29 =383 (deficient leap year) 30+29+30+29+30+29+30+29+30+29+30+30+29 =384 (regular leap year) 30+29+30+29+30+29+30+30+30+29+30+30+29 =385 (complete leap year)

New Year: The new year (Rosh Hashanah [or Rosh Hashana]) falls on Tishri 1, which falls at the mean

conjunction (new moon) or molad (plural is moladot) of Tishri, except in the case of one or more

"postponements" (dehiyyot): (1) If the mean conjunction is at midday or after, then Rosh Hashanah is delayed by a day. (2) Rosh Hashanah cannot fall on a Sunday (as this would make Hoshanah Rabba fall on Saturday) or Wednesday or Friday (as this would make Yom Kippur fall adjacent to the Sabbath). (3) If Rosh Hashanah falls on a Tuesday and the mean conjunction of Tishri for the following year is to fall after midday, application of the previous two rules would result in delaying the following Rosh Hashanah from Saturday until Monday and would cause an unacceptable year length of 356 days; instead, this year's Rosh Hashanah is delayed until Thursday. (4) Rosh Hashanah on Monday after a leap year can cause the finishing year to be too short, so Rosh Hashanah is delayed until Tuesday.

Years: Years in the Jewish Calendar are preceded by the abbreviation AM, from the Latin anno mundi (the year of the world). Days begin at sundown, and the week consists of seven days, ending with the Sabbath - the holiest of Jewish holidays - from sundown Friday to sundown Saturday.

Months: The year consists of 12 months:

� Nissan (or Nisan) (30 days),

� Iyar (or Iyyar) (29 days),

� Sivan (30 days),

� Tammuz (29 days),

� Av (30 days),

� Elul (29 days),

� Tishri (30 days),

� Heshvan (or Heschvan) (29 days, or 30 days in complete years),

� Kislev (30 days, or 29 days in deficient years),

� Tevet (or Teveth) (29 days),

� Shevat (or Shebat) (30 days),

� Adar (29 days, or 30 days [and called Adar I] in leap years), and

� Adar II (or ve-Adar) (29 days, intercalary month).

Twenty-nine-day months are called "deficient" (haser) months; thirty-day months are called "full" (male) months.

Days: Days run from sunset to sunset.

Other Divisions: The Jewish day is divided into 24 hours, which are each divided into 1,080 "parts" or

halakim (singular is helek). Traditionally, sunset is considered to be 6:00 P.M. and sunrise is considered to be 6:00 A.M., so (except on equinoxes) daytime hours and parts have different lengths than nighttime hours and parts. Commonly nowadays, though, sunrise and sunset time are calculated around fixed hour and helek lengths; the fixed hour lengths correspond to those of the Gregorian Calendar, halakim are

taken to equal 31/3 Gregorian Calendar seconds.

Intercalary/Leap System: To balance the Jewish Calendar with the solar year, an intercalary month,

Adar II, is added on the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th years of a 19-year cycle. The next 19-year

cycle begins with AM 5758, the night before NS October 2, 1997 CE. Common years can be between 353 and 355 days (inclusive); leap years can be between 383 and 385 days (inclusive).

Correlation to Gregorian: The Jewish year 5755 began (Tishri 1, 5755) at sunset the night before NS September 6, 1994 CE.

A couple of algorithms have been postulated by John Conway for identifying the date of Rosh Hashanah on the Gregorian Calendar:

John Conway's Algorithm:

G = Golden Number (see "Metonic Cycle" in "Calendar Calculations" section)

Y = Gregorian year

N = (INT(Y/100) - INT(Y/400) - 2) + 765433/492480 × (12G MOD 19) + (Y MOD 4)/4 - (313Y + 89081)/98496

Fraction = N - INT(N)

Rosh Hashanah falls on September N.

If September N is a Sunday, Wednesday, or Friday, Rosh Hashanah falls on the next day (respectively, Monday, Thursday, or Saturday).

If September N is a Monday, and if Fraction 23269/25920, and if 12G MOD 19 > 11, then Rosh Hashanah falls on the next day (Tuesday).

If September N is a Tuesday, and if Fraction 1367/2160, and if 12G MOD 19 > 6, Rosh Hashanah falls two days later (Thursday).

John Conway's Simpler Algorithm (works with dates between 1900 CE and 2099 CE):

G = Golden Number (see "Metonic Cycle" in "Calendar Calculations" section)

Y = Gregorian year

N = 6.057778996 + 1.554241797 × (12G MOD 19) + 0.25 × (Y MOD 4) - 0.003177794 × Y

Fraction = N - INT(N)

Rosh Hashanah falls on September N.

If September N is a Sunday, Wednesday, or Friday, Rosh Hashanah falls on the next day (respectively, Monday, Thursday, or Saturday).

If September N is a Monday, and if Fraction 23269/25920, and if 12G MOD 19 > 11, then Rosh Hashanah falls on the next day (Tuesday).

If September N is a Tuesday, and if Fraction 1367/2160, and if 12G MOD 19 > 6, Rosh Hashanah falls two days later (Thursday).

Other Cycles: The first month of the Jewish Calendar is Nissan, but the years augment at New Year's

(Rosh Hashanah), on the first day of Tishri. This is because the Jewish Calendar has several new year's beginnings:

� Nissan 1, for counting the reign of kings or the months on the calendar; � Elul 1, for the tithing of animals; � Shevat 1 (according to Beit Shammai) or Shevat 15 (according to Beit Hillel) for the counting of

years of trees (determining when first fruits can be eaten, etc.); and � Tishri 1, for the counting of years.

A Jewish birthday is celebrated on the anniversary of the birthdate according to the Jewish Calendar, with minor variations:

� Heshvan 30: If the birthdate was on Heshvan 30, it is celebrated on Kislev 1 in regular or deficient years (e.g., those in which Heshvan has only 29 days).

� Kislev 30: If the birthdate was on Kislev 30, it is celebrated on Tevet 1 in deficient years (e.g., those in which Kislev has only 29 days).

� Adar/Adar II: If the birthdate was in Adar (in a common year) or in Adar II (in a leap year), it is celebrated in Adar in common years and in Adar II in leap years (i.e., if the birthdate was in the last month of the year, it is celebrated in the last month of the year).

� Adar I: If the birthdate was in Adar I (in a leap year), it is celebrated in Adar in common years. � Adar I 30: If the birthdate was on Adar I 30 (in a leap year), it is celebrated on Nissan 1 in

common years.

An anniversary of the date of death (yahrzeit) is remembered in subsequent years on the death date, with minor variations (different from the variations for celebrating birthdays):

� Heshvan 30: If the death occurred on Heshvan 30 then (1) if the first anniversary of the death fell on Heshvan 30 (i.e., if the following year was complete), the yahrzeit is remembered on Heshvan 30 in complete years and on Kislev 1 in regular or deficient years, otherwise (2) it is remembered on the last day of Heshvan (Heshvan 30 in complete years, and Heshvan 29 in regular or deficient years).

� Kislev 30: Similarly If the death occurred on Kislev 30 then (1) if the first anniversary of the death fell on Kislev 30 (i.e., if the following year was regular or complete), the yahrzeit is remembered on Kislev 30 in regular or complete years and on Tevet 1 in deficient years, otherwise (2) it is remembered on the last day of Kislev (Kislev 30 in regular or complete years, and Kislev 29 in deficient years).

� Adar/Adar I: If the death occurred in Adar (in a common year) or in Adar I (in a leap year), the yahrzeit is remembered on the same day of Adar in common years and of Adar I in leap years.

� Adar II: If the death occurred in Adar II (in a leap year), the yahrzeit is remembered on the same day of Adar in common years and of Adar II in leap years.

� Adar I 30: If the death occurred on Adar I 30 (in a leap year), the yahrzeit is remembered on Shevat 30 in common years.

Holidays: Major holidays in the Jewish Calendar include:

� Rosh Hashanah (Tishri 1),

� Tzom Gedaliah (Tishri 3),

� Sukkot (Tishri 15),

� Hoshanah Rabba (Tishri 21),

� Shemini Azereth (Tishri 22),

� Simhat Torah (Tishri 23),

� Hanukkah (Kislev 25),

� Tzom Tevet (Tevet 10),

� Tu-B'Shevat (Shevat 15),

� Ta'anit Esther (the day before Purim, unless Purim falls on a Sunday, in which case it is the Thursday before Purim),

� Purim (Adar 14 in common years, and Adar II 14 in leap years),

� Passover (Nissan 15),

� Shavuot (Sivan 6),

� Tzom Tammuz (Tammuz 17), and

� Tisha B'Av (Av 9).

Julian Calendar

Other Names: Also called the Old Style Calendar. (Additionally, the Ethiopian Calendar - an entirely different system - is sometimes referred to as the Julian Calendar.)

Origin: The Julian Calendar is a reform of the Roman Calendar dating to 45 BCE, when Julius Caesar followed the advice of the Greek astronomer Sosigenes and decided to use a solar calendar. This Julian Calendar fixed the normal year at 365 days, and the leap year (every fourth year) at 366 days. The Julian Calendar established the order of the months and the days of the week as they exist in the present-day Gregorian Calendar.

Method: Solar.

Mathematics: 31+28+31+30+31+30+31+31+30+31+30+31=365 (common year) 31+29+31+30+31+30+31+31+30+31+30+31=366 (leap year)

New Year: The beginning of the year (as well as the start year and method of counting days) varied, depending on time, place, and sometimes even purpose (different systems were employed for such as religious records, financial events, personal correspondence, etc.). Caesar designated January 1 as the date of the new year, but many other conventions were followed; March 1, March 25, and December 25 were widely used.

Months: The months of the Julian Calendar are named differently in different languages. In English they are:

� January (31 days) (Nones is the 5th) (Ides is the 13th),

� February (28 days, 29 days in leap years) (Nones is the 5th) (Ides is the 13th),

� March (31 days) (Nones is the 7th) (Ides is the 15th),

� April (30 days) (Nones is the 5th) (Ides is the 13th),

� May (31 days) (Nones is the 7th) (Ides is the 15th),

� June (30 days) (Nones is the 5th) (Ides is the 13th),

� July (31 days)

(originally named quintilis, until 44 BCE) (Nones is the 7th) (Ides is the 15th),

� August (31 days)

(originally named sextilis, until 8 BCE) (Nones is the 5th) (Ides is the 13th),

� September (30 days)

(Nones is the 5th) (Ides is the 13th),

� October (31 days) (Nones is the 7th) (Ides is the 15th),

� November (30 days) (Nones is the 5th) (Ides is the 13th), and

� December (31 days) (Nones is the 5th) (Ides is the 13th).

Days: Days were originally counted down to three division points in a month, which were:

� Kalends (or Calends) (first day of the month),

� Nones (eight days before the Ides), and

� Ides (fifteenth day of March, May, July, and October; thirteenth day of all other months).

The day before one of these events was referred to as pridie.

Digits were rendered in Roman numerals, and were preceded by the abbreviation a.d. Thus for the month of February (in, for example, a leap year), the days were as follows:

� Kalends February (February 1),

� a.d. III Nones February (February 2),

� a.d. II Nones February (February 3),

� Pridie Nones February (February 4),

� Nones February (February 5),

� a.d. VII Ides February (February 6),

� a.d. VI Ides February (February 7),

� a.d. V Ides February (February 8),

� a.d. IV Ides February (February 9),

� a.d. III Ides February (February 10),

� a.d. II Ides February (February 11),

� Pridie Ides February (February 12),

� Ides February (February 13),

� a.d. XV Kalends March (February 14),

� a.d. XIV Kalends March (February 15),

� a.d. XIII Kalends March (February 16),

� a.d. XII Kalends March (February 17),

� a.d. XI Kalends March (February 18),

� a.d. X Kalends March (February 19),

� a.d. IX Kalends March (February 20),

� a.d. VIII Kalends March (February 21),

� a.d. VII Kalends March (February 22),

� a.d. VI Kalends March, bis (February 23) (leap day),

� a.d. VI Kalends March (February 24),

� a.d. V Kalends March (February 25),

� a.d. IV Kalends March (February 26),

� a.d. III Kalends March (February 27),

� a.d. II Kalends March (February 28), and

� Pridie Kalends March (February 29).

By the eleventh century, however, this system had been replaced by the one familiar in the Gregorian Calendar, counting days from the beginning of the month.

Intercalary/Leap System: The Julian Calendar added a leap day in February by repeating the day a.d

VI Kalends March, the initial occurrence being written as a.d VI Kalends March, bis. This leap day was designed to be added every fourth year (which caused a slight offset over the centuries that the Gregorian Calendar corrected). After Caesar's death, however, the leap year rule was misapplied and the leap day was added every third year. The situation was later corrected by mechanisms of which historians are not completely certain; most believe that Augustus corrected the situation by omitting intercalation from 8 BCE until 4 CE.

Correlation to Gregorian: The Julian Calendar is currently 13 days behind the Gregorian Calendar, and becomes one more day behind every time it has a leap day that is omitted in the Gregorian Calendar (every year evenly divisible by 100, but not evenly divisible by 400).

Julian Calendar dates are preceded by the abbreviation OS (Old Style), and Gregorian Calendar dates

are preceded by the abbreviation NS (New Style). (See Gregorian Calendar for more discussion of this issue.)

Other Cycles: A cycle of 10 years is called a decade; a cycle of 100 years is called a century; a cycle of

1000 years is called a millennium.

Holidays: The Julian Calendar is maintained as the calendar system for Orthodox Christian churches. Holidays vary among the branches of the Orthodox faiths, but main holidays include:

� Triodon (70 days before OS Easter),

� Saturday of Souls (57 days before OS Easter),

� Meat Fare (56 days before OS Easter),

� Second Saturday of Souls (50 days before OS Easter),

� Lent Begins (48 days before OS Easter),

� St. Theodore (43 days before OS Easter),

� Sunday of Orthodoxy (42 days before OS Easter),

� Saturday of Lazarus (8 days before OS Easter),

� Palm Sunday (7 days before OS Easter),

� Good Friday (2 days before OS Easter),

� Easter (see below),

� Ascension (39 days after OS Easter),

� Saturday of Souls (48 days after OS Easter),

� Pentecost (49 days after OS Easter),

� All Saints (56 days after OS Easter),

� Epiphany (OS January 6), and

� Christmas (OS December 25).

The algorithm for computing the Orthodox (Julian) Easter is:

R1 = Year MOD 19

R2 = Year MOD 4

R3 = Year MOD 7

RA = 19 × R1 + 16

R4 = RA MOD 30

RB = 2 × R2 + 4 × R3 + 6 × R4

R5 = RB MOD 7

RC = R4 + R5

RC is the number of days after March 21 in the Julian calendar.

Julian Calendar (Ethiopian) (See Ethiopian Calendar)

Julian Day

Origin: The Julian Day is the unit of a chronological system, created by Joseph Scaliger in 1582, and named for his father, Julius Caesar Scaliger. In it, any date is measured by counting the number of days from an arbitrary zero point: January 1, 4713 BCE, at noon, Greenwich time, which was the most recent date that the following cycles converged:

� The 28-year solar cycle after which days in the Julian Calendar return to the same day of the week,

� The 19-year Metonic Cycle (see "Metonic Cycle" in "Calendar Calculations" section), and � The 15-year Indication Cycle, used in Rome to regulate taxes (see "Roman Indication" in

"Calendar Calculations" section).

The Julian Day is now used mostly in astronomy to calculate the number of days between two widely

separated periodic events, such as eclipses. Julian Day dates are preceded by the abbreviation JD.

Method: Continuous.

Days: Days run from noon to noon.

Other Divisions: Periods shorter than a day are shown as a decimal.

Correlation to Gregorian: The Julian Day (JD) of NS January 1, 1980 CE (at noon UT) is JD 2,444,240.0.

Julian Day - Modified

Origin: The Modified Julian Day is a shortened version of the Julian Day chronological system. It simply subtracts 2,400,000.5 from the Julian Day (the 0.5 being subtracted because the Modified Julian Day begins at midnight rather than at noon). It counts the number of days elapsed since NS November

16, 1858 CE. Modified Julian Day dates are preceded by the abbreviation MJD.

Method: Continuous.

Days: Days run from midnight to midnight.

Other Divisions: Periods shorter than a day are shown as a decimal.

Correlation to Gregorian: The Julian Day (JD) of NS January 1, 1980 CE (at midnight UT) is MJD 44,240.0.

Julian Day - Truncated

Origin: The Truncated Julian Day is a shortened version of the Julian Day chronological system. It simply subtracts 2,440,000.5 from the Julian Day (the 0.5 being subtracted because the Truncated Julian Day begins at midnight rather than at noon) or 40,000 from the Modified Julian Day. It counts the number of days elapsed since NS May 23, 1968 CE. Truncated Julian Day dates are preceded by

the abbreviation TJD.

Method: Continuous.

Days: Days run from midnight to midnight.

Other Divisions: Periods shorter than a day are shown as a decimal.

Correlation to Gregorian: The Julian Day (JD) of NS January 1, 1980 CE (at midnight UT) is TJD 4,240.0.

Long Count (See Mayan Calendar - Long Count)

Mayan Calendar - Haab

Other Names: Also called the Haab, Haab Calendar.

Origin: One of the three systems of the Mayan Calendar (the others being the Long Count and the

Tzolkin), the Haab was the Mayan civil calendar.

Method: Solar.

Mathematics: 18×20+5=365

Years: The Haab counts days and months, but years are not designated.

Months: The Haab has 18 twenty-day months, the names of which are:

� Pohp (Mat),

� Wo (?),

� Sip (?),

� Sotz' (Bat),

� Sek (?),

� Xul (Dog),

� Yaxk'in (New Sun),

� Mol (Water),

� Ch'en (Black?),

� Yax (Green?),

� Zak (White?),

� Keh (Red?),

� Mak (?),

� K'ank'in (?),

� Muwan (Owl),

� Pax (?),

� K'ayab (Turtle), and

� Kumk'u (?).

Days: The days of the Haab months are numbered from zero to nineteen (to indicate the number of days elapsed in each month).

Conformity to Solar Year: To bring the calendar to 365 days, the Maya appended a month called

Wayeb, five "days of evil omen" of which were considered unnamed and unlucky.

Intercalary/Leap System: Although the Maya were aware of the discrepancy between their 365-day calendar and the actual solar year, they did not account for it in their system. Therefore, the Maya calendar drifted slowly backward through the seasons.

Correlation to Gregorian: The Mayan Long Count 0.0.0.0.0 correlated to the Haab date 8 Kumk'u, but there is significant discrepancy as to the Gregorian Calendar date that correlated to 0.0.0.0.0 (see below in Mayan Calendar - Long Count).

Other Cycles: The 260-day Tzolkin Calendar (see below in Mayan Calendar - Tzolkin) and 365-day Haab ran concurrently, forming a long cycle of 18,980 days, which was called a Calendar Round. Dates in the Calendar Round are given by indicating first the Tzolkin date and then the Haab date, such as 11 Chuwen 19 K'ayab.

Mayan Calendar - Long Count

Other Names: Also called the Long Count.

Origin: One of the three systems of the Mayan Calendar (the others being the Haab and the Tzolkin), the Long Count is a cycle of 2,880,000 days (about 7,885 years), at the end of which the Maya believed the universe is destroyed and re-created.

Method: 2,880,000-day cycle (for all practical purposes, continuous).

Mathematics: 20×20×20×18×20=2880000

Divisions: The units of the Long Count are:

� kin (1 day),

� uinal (or winal) (20 kin) (20 days),

� tun (18 uinal) (360 days),

� katun (20 tun) (7,200 days), and

� baktun (20 katun) (144,000 days).

A Long Count date of 12.16.11.16.6 would therefore mean 12 baktun, 16 katun, 11 tun, 16 uinal, and 6 kin.

Correlation to Gregorian: The beginning date of the Long Count is uncertain, but the two most

common correlations for the Long Count date 0.0.0.0.0 are the Goodman-Martinez-Thompson Correlation

(which fixes it at NS August 13, 3113 BCE) and Spinden's Correlation (which fixes it at NS October 15, 3373 BCE).

Other Cycles: The Maya also had units of measurement for time periods greater than a full Long Count:

� pictun (20 baktun) (2,880,000 days),

� calabtun (20 pictun) (57,600,000 days),

� kinchiltun (20 calabtun) (1,152,000,000 days), and

� alautun (20 kinchiltun) (23,040,000,000 days).

Additionally, the Maya later came to use a Short Count, which simply dropped the baktun from the date and named each katun for the date on which it ended in the Tzolkin Calendar (see below in Mayan Calendar - Tzolkin), which was always a date Ahaw. The sequence turned out to be:

� 2 Ahaw, � 13 Ahaw, � 11 Ahaw, � 9 Ahaw, � 7 Ahaw, � 5 Ahaw, � 3 Ahaw, � 1 Ahaw, � 12 Ahaw, � 10 Ahaw, � 8 Ahaw, � 6 Ahaw, and finally � 4 Ahaw (after which it repeated).

The Maya therefore would refer to an event has having happened in, for example, Katun 7 Ahaw (meaning the katun that ended on 7 Ahaw). In addition to being paired with the last four figures of the Long Count, these katun sequences could also be paired with the Calendar Round date (see above in Mayan Calendar - Haab and below in Mayan Calendar - Tzolkin).

Mayan Calendar - Tzolkin

Other Names: Also called the Tzolkin Calendar, Divine Calendar.

Origin: One of the three systems of the Mayan Calendar (the others being the Long Count and the

Haab), the Tzolkin Calendar was the Mayan religious calendar ("Tzolkin" means "Divine").

Method: 260-day cycle. The Tzolkin Calendar used two independent cycles which advanced simultaneously - a thirteen-day count and a twenty-name cycle. The names are as follows:

� Imix (Waterlily),

� Ik' (Wind),

� Ak'bal (Night),

� K'an (Corn),

� Chikchan (Snake),

� Kimi (Death Head),

� Manik' (Hand),

� Lamat (Venus),

� Muluk (Water),

� Ok (Dog),

� Chuwen (Frog),

� Eb (Skull),

� Ben (Corn Stalk),

� Ix (Jaguar),

� Men (Eagle),

� Kib (Shell),

� Kaban (Earth),

� Etz'nab (Flint),

� Kawak (Storm Cloud), and

� Ahaw (or Ahau) (Lord).

The count and names advance independently, thus 13 Etz'nab is followed by 1 Kawak, which is followed by 2 Ahaw, which is followed by 3 Imix, etc. This results in 260 distinct dates.

Mathematics: 13×20=260

Years: At the end of its cycle, the Tzolkin Calendar merely resets; there is no system (analogous to counting years) for distinguishing one Tzolkin Calendar cycle from another.

Correlation to Gregorian: The Mayan Long Count 0.0.0.0.0 correlated to the Tzolkin Calendar date 4 Ahaw, but there is significant discrepancy as to the Gregorian Calendar date that correlated to 0.0.0.0.0 (see above in Mayan Calendar - Long Count).

Other Cycles: The 260-day Tzolkin Calendar and 365-day Haab Calendar (see above in Mayan Calendar - Haab) ran concurrently, forming a long cycle of 18,980 days, which was called a Calendar Round. Dates in the Calendar Round are given by indicating first the Tzolkin date and then the Haab date, such as 11 Chuwen 19 K'ayab.

Metonic Calendar (See Grecian Calendar)

Muslim Calendar (See Islamic Calendar)

Nabonassar Calendar (See Babylonian Calendar)

New Style Calendar (See Gregorian Calendar)

Old Style Calendar (See Julian Calendar)

Parsi Calendar (See Zoroastrian Calendar - Shahanshahi)

Pawukon Calendar (See Balinese Calendar - Pawukon)

Perpetual Calendar

Origin: The Perpetual Calendar is a modification of the World Calendar, identical except that the first day of each quarter begins on a Monday (rather than a Sunday, as in the World Calendar) insofar as this is beneficial in some ways to businesses. It is based on a 52-week, 364-day year starting on Monday,

January 1, with the 365th day, called Year-End Day, added without date or day of the week. In leap years

an extra Leap-Year Day, also without date or day of the week, is inserted at the end of the 26th week, between the last day of June and the first day of July. The first month of each quarter has 31 days, and all

the others have 30 days.

Method: Solar.

Mathematics: ((31+30+30)×4)+1=365 (common year) ((31+30+30)×4)+1+1=366 (leap year)

New Year: New Year's Day is January 1.

Months: The World Calendar is divided into 12 months with the same names as in the Gregorian Calendar. The first month of each quarter has 31 days, and all the others have 30 days:

� January (31 days),

� February (30 days),

� March (30 days),

� April (31 days),

� May (30 days),

� June (30 days),

� July (31 days),

� August (30 days),

� September (30 days),

� October (31 days),

� November (30 days), and

� December (30 days).

Days: The World Calendar follows the seven day week, the names of the days being the same as in the Gregorian Calendar. The first day of each quarter falls on a Monday.

Other Divisions: Identical to the Gregorian Calendar.

Conformity to Solar Year: To bring the calendar to 365 days, a Year-End Day is added, without date or day of the week, after December 30.

Intercalary/Leap System: In leap years an extra Leap-Year Day, also without date or day of the week, is inserted at the end of the 26th week, between the last day of June and the first day of July.

Correlation to Gregorian: Year numbers are the same, leap years are the same. January 1 by the World Calendar is the same as NS January 1.

Persian Calendar (See Jalaali Calendar)

Qadimi Calendar (See Zoroastrian Calendar - Qadimi)

Quaker Calendar

Other Names: Also called the Friends Calendar.

Origin: Quakers (the Society of Friends) removed pagan references in the names of months and day by replacing them with cardinal numbers. Otherwise, the calendar is identical to the Gregorian Calendar.

These names are not in common usage today, even among Quakers, but they do appear occasionally in Friends' events (especially those originally named when usage was common) such as "First Day School."

Method: Solar; identical to the Gregorian Calendar.

Mathematics: Identical to the Gregorian Calendar.

New Year: Identical to the Gregorian Calendar: 1st Month 1.

Months: The months are:

� 1st Month (January, 31 days),

� 2nd Month (February, 28 days, 29 days in leap years),

� 3rd Month (March, 31 days),

� 4th Month (April, 30 days),

� 5th Month (May, 31 days),

� 6th Month (June, 30 days),

� 7th Month (July, 31 days),

� 8th Month (August, 31 days),

� 9th Month (September, 30 days),

� 10th Month (October, 31 days),

� 11th Month (November, 30 days), and

� 12th Month (December, 31 days).

Like those who use the more traditional names in the Gregorian Calendar, the Friends employ a rhyme to remember which months have what number of days:

"Fourth, eleventh, ninth, and sixth, Thirty days to each affix; Every other thirty-one Except the second month alone."

Days: The days are:

� 1st Day (Sunday),

� 2nd Day (Monday),

� 3rd Day (Tuesday),

� 4th Day (Wednesday),

� 5th Day (Thursday),

� 6th Day (Friday), and

� 7th Day (Saturday).

As in the Gregorian Calendar, days run from midnight to midnight.

Other Divisions: Identical to the Gregorian Calendar.

Intercalary/Leap System: Identical to the Gregorian Calendar.

Correlation to Gregorian: Identical.

Other Cycles: Identical to the Gregorian Calendar.

Republican Calendar

Other Names: Also called the French Republican Calendar.

Origin: During the French Revolution, the Republican Calendar was adopted to rid the calendar of religious connections.

Method: Solar. The Republican Calendar had 12 months of 30 days with 5 celebratory days at the end (or 6 in leap years).

Mathematics: 12×30+5=365 (common year) 12×30+6=366 (leap year)

New Year: The year begins with 1 Vendémiaire.

Years: Years are preceded by the word An, French for "Year." A longer way of referring to dates is

evidenced in 18 Brumaire de l'An VIII de la République Française une et indivisible ("18 Brumaire of Year VIII of the French Republic, one and indivisible").

Months: The months are called:

� Vendémiaire (vintage),

� Brumaire (mist),

� Frimaire (frost),

� Nivôse (snow),

� Pluviôse (rain),

� Ventôse (wind),

� Germinal (sprouting time),

� Floréal (blossom),

� Prairial (meadow),

� Messidor (harvest),

� Thermidor (heat), and

� Fructidor (fruit).

(It bears note that British wits dubbed these months as Slippy, Nippy, Drippy, Freezy, Wheezy, Sneezy, Showery, Flowery, Bowery, Wheaty, Heaty, and Sweety.)

Days: Each month consisted of three 10-day weeks, the last day of each week being a day of rest. The names of these days are:

� Primidi, � Doudi, � Tridi, � Quartidi, � Quintidi, � Sextidi, � Septidi, � Oxtidi, � Nonidi, and

� Decadi (day of rest).

Conformity to Solar Year: Five celebratory days, called sans-culottides (literally, "without pants,"

referring to the style of dress of the Revolutionists) or, later, Jours Complémentaires ("Complimentary

Days") are appended at the end of the year. In leap years an additional day, a sans-culottide par

excellence, is appended. The names of these days are:

� Jour de la Vertu (Virtue Day),

� Jour du Genie (Genius Day),

� Jour du Labour (Labor Day),

� Jour de la Raison (Reason Day),

� Jour de la Recompense (Reward Day), and

� Jour de la Revolution (Revolution Day) (sans-culottide par excellence, leap years).

Intercalary/Leap System: Originally, the calendar proposed to use a leap system to force 1 Vendémiaire to fall on the autumnal equinox. When this was found to be impractical, it was decided that after the 20th year (although the Republican Calendar didn't survive in common usage for 20 years) the leap system would be similar to the Gregorian Calendar in that:

� every 4th year is a leap year, except � every 100th year is not a leap year, except � every 400th year is a leap year, except � every 4000th year is not a leap year (this last variation does not occur in the Gregorian Calendar).

For the first 20 years, of the calendar, the following were leap years:

� An 3, � An 7, � An 11, � An 15, and � An 20.

Correlation to Gregorian: The calendar began with An 1 (1 Vendémiaire, An 1) on NS September 22, 1792 CE, the day the republic was proclaimed.

Roman Calendar

Other Names: Also called the "Ab Urbe Condita" ("from the building of the city" [Rome]) calendar.

Origin: The original Roman Calendar, precursor to the Julian Calendar, was introduced c. 650 BCE and had a 10-month year of 304 days. It numbers its years from the construction of Rome, which Varro calculated to have occurred in 753 BCE.

The Roman Calendar, however, became profoundly out-of-sync with the solar year as well as with the lunar cycle. The year 45 BCE has been called the "Year of Confusion" because then, in his first step toward calendar reform (which eventually led to the Julian Calendar), Caesar added 90 days to bring the months of the Roman Calendar back to their traditional points relative to the seasons.

Method: Lunisolar.

Mathematics: 29+28+31+29+31+29+31+29+29+31+29+29=355

New Year: The year began at the vernal equinox.

Years: Years of the Roman Calendar were 355 days long.

Months: The original months were:

� Martius (March) (for Mars) (31 days),

� Aprilis (April) (Romans considered the month sacred to Venus, and Aprilis may be from Venus's Greek equivalent, Aphrodite) (29 days),

� Maius (May) (probably for the Maia) (31 days),

� Junius (or Iunius) (June) (for Juno) (29 days),

� quintilis (July) (from quin, meaning five) (named Julius [or Iulius], for Julius Caesar in 44 BCE) (31 days),

� sextilis (August) (from sex, meaning six) (named Augustus for the emperor Augustus in 8 BCE) (29 days),

� september (September) (from septem, meaning seven) (29 days),

� october (October) (from octo, meaning eight) (31 days),

� november (November) (from nove, meaning nine) (29 days), and

� december (December) (from decem, meaning ten) (29 days).

The Roman Calendar may have included two unnamed months in the winter. In the 7th century BCE,

two additional named months were added before Martius:

� Januarius (or Ianuarius) (January) (for Janus, god of beginnings and doorways) (29 days) and

� Februarius (February) (for Februa, feast of purification) (28 days).

Still, an extra month had to be intercalated approximately every second year. It began after the twenty-

third day of Februarius, with the remainder of Februarius being omitted.

The Roman Calendar was governed by the High Priest, and on the day of the new moon - which

corresponded to the Kalends (or Calends) - the High Priest would announce the times of the Nones (first

quarter) and Ides (full moon). This resulted in a convention wherein the Nones was 8 days before the Ides, and the Ides was the fifteenth day of Martius, Maius, quintilis, and october, and the thirteenth day of all other months.

Days: The days of the month were designated by counting (written with Roman numerals) backward

from the Kalends, the Nones, and the Ides. The day before one of these was designated as Pridie Kalends,

Pridie Nones, or Pridie Ides, respectively. (See Julian Calendar for more discussion of this system).

Conformity to Solar Year: The Roman Calendar was designed to conform to the solar year, but, in fact, it failed to do so.

Intercalary/Leap System: An extra month was intercalated approximately every other year.

Correlation to Gregorian: Year 2749 of the Roman Calendar began on NS January 14, 1996 CE.

Roman Republican Calendar (See Roman Calendar)

Saka Calendar (See Hindu Calendar - Civil)

Sasih Cycle (See Balinese Calendar - Sasih)

Seleucidae Calendar (See Grecian Calendar)

Shahanshahi Calendar (See Zoroastrian Calendar - Shahanshahi)

Shenshai Calendar (See Zoroastrian Calendar - Shahanshahi)

Sumerian Calendar (See Babylonian Calendar)

Thirteen Month Calendar (See International Fixed Calendar)

Tzolkin Calendar (See Mayan Calendar - Tzolkin)

World Calendar

Origin: The World Calendar was considered in the United Nations in 1954. It is based on a 52-week,

364-day year starting on Sunday, January 1, with the 365th day, called Year-End Day, added without date

or day of the week. In leap years an extra Leap-Year Day, also without date or day of the week, is inserted at the end of the 26th week, between the last day of June and the first day of July. The first month of each quarter has 31 days, and all the others have 30 days.

Method: Solar.

Mathematics: ((31+30+30)×4)+1=365 (common year) ((31+30+30)×4)+1+1=366 (leap year)

New Year: New Year's Day is January 1.

Months: The World Calendar is divided into 12 months with the same names as in the Gregorian Calendar. The first month of each quarter has 31 days, and all the others have 30 days:

� January (31 days),

� February (30 days),

� March (30 days),

� April (31 days),

� May (30 days),

� June (30 days),

� July (31 days),

� August (30 days),

� September (30 days),

� October (31 days),

� November (30 days), and

� December (30 days).

Days: The World Calendar follows the seven day week, the names of the days being the same as in the Gregorian Calendar. The first day of each quarter falls on a Sunday.

Other Divisions: Identical to the Gregorian Calendar.

Conformity to Solar Year: To bring the calendar to 365 days, a Year-End Day is added, without date or day of the week, after December 30.

Intercalary/Leap System: In leap years an extra Leap-Year Day, also without date or day of the week, is inserted at the end of the 26th week, between the last day of June and the first day of July.

Correlation to Gregorian: Year numbers are the same, leap years are the same. January 1 by the World Calendar is the same as NS January 1.

Zoroastrian Calendar - Fasli

Other Names: Also called the Fasli Calendar.

Origin: This calendar is a variation of the Zoroastrian Shahanshahi Calendar (see Zoroastrian Calendar - Shahanshahi). It was an outgrowth of a movement started in 1906 by Khurshedji Cama, who was disturbed that the new year no longer fell in Spring. This Fasli (seasonal) movement adopted a leap year system which tracked the Gregorian Calendar, so that the new year would always fall on NS March 21. It is forbidden, however, in the traditional Denkard for a sixth day to be added every four years, so this calendar is hardly universal among Zoroastrians.

Method: Solar. The calendar has 12 months of 30 days each, with a 5- or 6-day period appended at the end.

Mathematics: 12×30+5=365 (common year) 12×30+6=366 (leap year)

New Year: New Year is the Ohrmazd day of Frawardin.

Years: Zoroastrian Calendars date from the coronation of the last Zoroastrian Sasanian King, Yazdegird

II, in 631 CE. For this reason, dates in Zoroastrian calendars are followed by the letter Y.

Months: Like the other Zoroastrian calendars, the Fasli Calendar is divided into twelve months as follows:

� Frawardin (or Fravardin),

� Ardwahisht (or Ardibehest),

� Hordad (or Khordad),

� Tir, � Amurdad (or Amardad),

� Shahrewar (or Shehrevar, or Shehrever),

� Mihr (or Meher),

� Aban (or Avan),

� Adur (or Adar),

� Dae,

� Bahman, and

� Spendarmad (or Aspandarmad).

Days: As in the other Zoroastrian calendars, each month of the Fasli Calendar is divided into thirty named days as follows:

� Ohrmazd (or Hormazd),

� Vohuman (or Bahman),

� Ardwahisht (or Ardibehest),

� Shahrewar (or Shehrevar),

� Spandarmad (or Asfandarmad),

� Hordad (or Khordad),

� Amurdad (or Amardad),

� DaepaAdar (or Daepadar),

� Adar, � Aban (or Avan),

� Khwarshed (or Khorshed),

� Mah (or Mohor),

� Tir or Tishtar, � Goshorun (or Gosh),

� DaepaMihr (or Daepmeher),

� Mihr (or Meher),

� Srosh,

� Rashnu (or Rashne),

� Frawardin (or Fravardin),

� Warharan or Behram,

� Ram,

� Wad or Gowad (or Govad),

� DaepaDen (or Daepdin),

� Den (or Din),

� Ard or Ashishvangh,

� Ashtad,

� Asman,

� Zam or Zamhad (or Zamyad),

� Mahraspand (or Mahrespand), and

� Anagran (or Aneran).

Other Divisions: As in the other Zoroastrian calendars, each day of the Fasli Calendar is divided into

gahs (watches):

� Hawan (sunrise to noon),

� Rapithwin or Second Hawan (noon to 3:00 P.M.),

� Uzerin (3:00 P.M. to sunset),

� Aiwisruthrem (sunset to midnight), and

� Ushahin (midnight to sunrise).

Conformity to Solar Year: A five-day period called Hamaspathmaidyen is appended at the end of the

year. (Some systems refer to these as gatha days and consider them a portion of the 12th month,

Spendarmad; Parsi Mukhtad adds 5 days to the beginning of the year.). These days are named:

� Ahunawad (or Ahunavad),

� Ushtawad (or Ushtavad),

� Spentomad,

� Wohukhshathra (or Vohukhshathra), and

� Wahishtoisht (or Vahishtoist).

Intercalary/Leap System: This calendar is distinguished from other Zoroastrian system by the addition of a sixth day in the Hamaspathmaidyen period, giving it a leap system which tracks the Gregorian Calendar.

Correlation to Gregorian: New Year always correlates to NS March 21.

Zoroastrian Calendar - Qadimi

Other Names: Also called the Qadimi Calendar (or Kadmi Calendar).

Origin: This calendar differs by one month from the Shehanshahi Calendar (see Zoroastrian Calendar - Shahanshahi). In 1720 CE, Jamasp Vilayati, an Iranian Dastur, went to India to advise on religious issues. A one-month difference was found between the Parsi and Iranian calendars, which no one could at that time explain - and both groups felt their calendar was the accurate one. In 1746 CE, a group of priests from Surat, referring to themselves as the "Kadim" (or "ancient ones") adopted the Iranian calendar.

Method: Was originally designed to be solar, but is now a 365-day cycle.

Mathematics: 12×30+5=365 (common year) (13×30+5=395 [leap year, no longer used])

New Year: New Year is the Ohrmazd day of Frawardin.

Years: Zoroastrian Calendars date from the coronation of the last Zoroastrian Sasanian King, Yazdegird

II, in 631 CE. For this reason, dates in Zoroastrian calendars are followed by the letter Y.

Months: Like the other Zoroastrian calendars, the Qadimi Calendar is divided into twelve months as follows:

� Frawardin (or Fravardin),

� Ardwahisht (or Ardibehest),

� Hordad (or Khordad),

� Tir, � Amurdad (or Amardad),

� Shahrewar (or Shehrevar, or Shehrever),

� Mihr (or Meher),

� Aban (or Avan),

� Adur (or Adar),

� Dae,

� Bahman, and

� Spendarmad (or Aspandarmad).

Days: As in the other Zoroastrian calendars, each month of the Qadimi Calendar is divided into thirty named days as follows:

� Ohrmazd (or Hormazd),

� Vohuman (or Bahman),

� Ardwahisht (or Ardibehest),

� Shahrewar (or Shehrevar),

� Spandarmad (or Asfandarmad),

� Hordad (or Khordad),

� Amurdad (or Amardad),

� DaepaAdar (or Daepadar),

� Adar, � Aban (or Avan),

� Khwarshed (or Khorshed),

� Mah (or Mohor),

� Tir or Tishtar, � Goshorun (or Gosh),

� DaepaMihr (or Daepmeher),

� Mihr (or Meher),

� Srosh,

� Rashnu (or Rashne),

� Frawardin (or Fravardin),

� Warharan or Behram,

� Ram,

� Wad or Gowad (or Govad),

� DaepaDen (or Daepdin),

� Den (or Din),

� Ard or Ashishvangh,

� Ashtad,

� Asman,

� Zam or Zamhad (or Zamyad),

� Mahraspand (or Mahrespand), and

� Anagran (or Aneran).

Other Divisions: As in the other Zoroastrian calendars, each day of the Qadimi Calendar is divided into

gahs (watches):

� Hawan (sunrise to noon),

� Rapithwin or Second Hawan (noon to 3:00 P.M.),

� Uzerin (3:00 P.M. to sunset),

� Aiwisruthrem (sunset to midnight), and

� Ushahin (midnight to sunrise).

Conformity to Solar Year: A five-day period called Hamaspathmaidyen is appended at the end of the

year. (Some systems refer to these as gatha days and consider them a portion of the 12th month,

Spendarmad; Parsi Mukhtad adds 5 days to the beginning of the year.). These days are named:

� Ahunawad (or Ahunavad),

� Ushtawad (or Ushtavad),

� Spentomad,

� Wohukhshathra (or Vohukhshathra), and

� Wahishtoisht (or Vahishtoist).

Intercalary/Leap System: This calendar was originally designed to track the solar year through the

addition of an intercalary month (called Spendarmad, as is the 12th month) every 120 years. Apparently, however, this was last done in 1009 CE. The calendar cycles slowly through the seasons, and derives its "authenticity" through the fact that New Year will come again in Spring in the year 2587 CE.

Correlation to Gregorian: The year 1364 Y (some sources say 1365 Y) began on NS July 24, 1995 CE.

Zoroastrian Calendar - Shahanshahi

Other Names: Also called the Shahanshahi Calendar, Shenshai Calendar, Parsi Calendar.

Origin: Shenshai means "royalist." This calendar differs by one month from the Qadimi Calendar (see Zoroastrian Calendar - Qadimi).

Method: Was originally designed to be solar, but is now a 365-day cycle.

Mathematics: 12×30+5=365 (common year) (13×30+5=395 [leap year, no longer used])

New Year: New Year is the Ohrmazd day of Frawardin.

Years: Zoroastrian Calendars date from the coronation of the last Zoroastrian Sasanian King, Yazdegird

II, in 631 CE. For this reason, dates in Zoroastrian calendars are followed by the letter Y.

Months: Like the other Zoroastrian calendars, the Qadimi Calendar is divided into twelve months as follows:

� Frawardin (or Fravardin),

� Ardwahisht (or Ardibehest),

� Hordad (or Khordad),

� Tir, � Amurdad (or Amardad),

� Shahrewar (or Shehrevar),

� Mihr (or Meher),

� Aban (or Avan),

� Adur (or Adar),

� Dae,

� Bahman, and

� Spendarmad (or Aspandarmad).

Days: As in the other Zoroastrian calendars, each month of the Qadimi Calendar is divided into thirty named days as follows:

� Ohrmazd (or Hormazd),

� Vohuman (or Bahman),

� Ardwahisht (or Ardibehest),

� Shahrewar (or Shehrevar, or Shehrever),

� Spandarmad (or Asfandarmad),

� Hordad (or Khordad),

� Amurdad (or Amardad),

� DaepaAdar (or Daepadar),

� Adar, � Aban (or Avan),

� Khwarshed (or Khorshed),

� Mah (or Mohor),

� Tir or Tishtar, � Goshorun (or Gosh),

� DaepaMihr (or Daepmeher),

� Mihr (or Meher),

� Srosh,

� Rashnu (or Rashne),

� Frawardin (or Fravardin),

� Warharan or Behram,

� Ram,

� Wad or Gowad (or Govad),

� DaepaDen (or Daepdin),

� Den (or Din),

� Ard or Ashishvangh,

� Ashtad,

� Asman,

� Zam or Zamhad (or Zamyad),

� Mahraspand (or Mahrespand), and

� Anagran (or Aneran).

Other Divisions: As in the other Zoroastrian calendars, each day of the is divided into gahs (watches):

� Hawan (sunrise to noon),

� Rapithwin or Second Hawan (noon to 3:00 P.M.),

� Uzerin (3:00 P.M. to sunset),

� Aiwisruthrem (sunset to midnight), and

� Ushahin (midnight to sunrise).

Conformity to Solar Year: A five-day period called Hamaspathmaidyen is appended at the end of the

year. (Some systems refer to these as gatha days and consider them a portion of the 12th month,

Spendarmad; Parsi Mukhtad adds 5 days to the beginning of the year.). These days are named:

� Ahunawad (or Ahunavad),

� Ushtawad (or Ushtavad),

� Spentomad,

� Wohukhshathra (or Vohukhshathra), and

� Wahishtoisht (or Vahishtoist).

Intercalary/Leap System: This calendar was originally designed to track the solar year through the addition of an intercalary month (called Spendarmad, as is the 12th month) every 120 years. Apparently, however, this was last done in 1129 CE. The calendar cycles slowly through the seasons, and derives its "authenticity" through the fact that New Year will come again in Spring in the year 2587 CE.

Correlation to Gregorian: The year 1364 Y (some sources say 1365 Y) began on NS August 23, 1995 CE.