Japanese calendar types have included a range of official and unofficial systems. At present, Japan uses the Gregorian calendar together with year designations stating the year of the reign of the current Emperor; the lunisolar Chinese calendar was introduced to Japan via Korea in the middle of the sixth century. After that, Japan calculated its calendar using various Chinese calendar procedures, from 1685, using Japanese variations of the Chinese procedures, but in 1873, as part of Japan's Meiji period modernization, a calendar based on the solar Gregorian calendar was introduced. In Japan today, the old Chinese calendar is ignored. Japan has had more than one system for designating years. Including: The Chinese sexagenary cycle was introduced early into Japan, it was used together with era names, as in the 1729 Ise calendar shown above, for "the 14th year of Kyōhō, tsuchi-no-to no tori", i.e. 己酉. Now, the cycle is used except around New Year; the era name system was introduced from China, has been in continuous use since AD 701.
Since the Taishō Emperor's ascension in 1912, each emperor's reign has begun a new era. Nengō are the official means of dating years in Japan, all government business is conducted using that system, it is in general use in private and personal business. The Japanese imperial year is based on the date of the legendary founding of Japan by Emperor Jimmu in 660 BC, it was first used in the official calendar in 1873. However, it never replaced era names, since World War II has been abandoned; the Western Common Era system has come into common use since the Meiji period. Now, most people know it, as well as era names; the official dating system known as nengō, has been in use since the late 7th century. Years are numbered within eras. Beginning with Meiji, each reign has been one era, but many earlier Emperors decreed a new era upon any major event; the nengō system remains in wide use on official documents and government forms. The imperial year system was used from 1872 to the Second World War. Imperial year 1 was the year when the legendary Emperor Jimmu founded Japan – 660 BC according to the Gregorian Calendar.
Usage of kōki dating can be a nationalist signal, pointing out that the history of Japan's imperial family is longer than that of Christianity, the basis of the Anno Domini system. Kōki 2600 was a special year; the 1940 Summer Olympics and Tokyo Expo were planned as anniversary events, but were canceled due to the Second Sino-Japanese War. The Japanese naval Zero Fighter was named after this year. After the Second World War, the United States occupied Japan, stopped the use of kōki by officials. Today, kōki is used, except in some judicial contexts; the 1898 law determining the placement of leap years is based on the kōki years, using a formula, equivalent to that of the Gregorian calendar: if the kōki year number is evenly divisible by four, it is a leap year, unless the number minus 660 is evenly divisible by 100 and not by 400. Thus, for example, the year Kōki 2560 is divisible by 4; the Japanese government has announced a new period of year on 2019 April Reiwa. The Heisei Period will end on 2019 April 30 and so the new period of year is expected to start on first of May 2019.
See "Seasonal days", below. The modern Japanese names for the months translate to "first month", "second month", so on; the corresponding number is combined with the suffix 月. The table below uses traditional numerals. In addition, every month has a traditional name, still used by some in fields such as poetry; the opening paragraph of a letter or the greeting in a speech might borrow one of these names to convey a sense of the season. Some, such as Yayoi and Satsuki, do double duty as given names; these month names appear from time to time on jidaigeki, contemporary television shows and movies set in the Edo period or earlier. The old Japanese calendar was an adjusted lunar calendar based on the Chinese calendar, the year—and with it the months—started anywhere from about 3 to 7 weeks than the modern year, so in historical contexts it is not accurate to equate the first month with January. Japan uses a seven-day week, aligned with the Western calendar; the seven-day week, with names for the days corresponding to the Latin system, was brought to Japan around AD 800 with the Buddhist calendar.
The system was used for astrological purposes and little else until 1876. The names of the days come from the five visible planets, which in turn are named after the five Chinese elements, from the moon and sun. On the origin of the names of the days of the week see East Asian Seven Luminaries. Sunday and Saturday are regarded as "Western style take-a-rest days". Since the late 19th century, Sunday has been regarded as a "full-time holiday", Saturday a half-time holiday; these holidays have no religious meaning. Many Japanese retailers
Jōji was a Japanese era name of the Northern Court during the Era of Northern and Southern Courts after Kōan and before Ōan. This period spanned the years from September 1362 through February 1368; the emperor in Kyoto was Emperor Go-Kōgon. Go-Kōgon's Southern Court rival in Yoshino during this time-frame was Emperor Go-Murakami. During the Meiji period, an Imperial decree dated March 3, 1911 established that the legitimate reigning monarchs of this period were the direct descendants of Emperor Go-Daigo through Emperor Go-Murakami, whose Southern Court had been established in exile in Yoshino, near Nara; until the end of the Edo period, the militarily superior pretender-Emperors supported by the Ashikaga shogunate had been mistakenly incorporated in Imperial chronologies despite the undisputed fact that the Imperial Regalia were not in their possession. This illegitimate Northern Court had been established in Kyoto by Ashikaga Takauji. 1362 called Jōji gannen: The new era name was created to mark an event or series of events.
The previous era ended and the new one commenced in Kōan 2. In this time frame, Shōhei was a Southern Court equivalent nengō, 1362: The era begins with Ashikaga Yoshiakira in control of Kyoto. 1365: Emperor Go-Daigo's son, Prince Kaneyoshi gains control of Kyūshū. 1367: Kantō Kubō Ashikaga Motouji dies. 1368: Yoshiakira's son, Ashikaga Yoshimitsu, becomes the third shōgun of what comest to be known as the Muromachi period. Ackroyd, Joyce. Lessons from History: The Tokushi Yoron. Brisbane: University of Queensland Press. ISBN 978-0-7022-1485-1 Mehl, Margaret.. History and the State in Nineteenth-Century Japan. New York: St Martin's Press. ISBN 978-0-312-21160-8. Japan Encyclopedia. Cambridge: Harvard University Press. ISBN 978-0-674-01753-5. Reconfiguring Modernity: Concepts of Nature in Japanese Political Ideology. Berkeley: University of California Press. ISBN 978-0-520-22854-2. Nihon Odai Ichiran. Paris: Royal Asiatic Society, Oriental Translation Fund of Great Britain and Ireland. OCLC 5850691 National Diet Library, "The Japanese Calendar" -- historical overview plus illustrative images from library's collection
The Republic of China calendar is the official calendar of the Republic of China. It is used to number the years for official purposes only in the Taiwan area after 1949, it was used in the Chinese mainland from 1912 until the establishment of the People's Republic of China in 1949. Following the Chinese imperial tradition of using the sovereign's era name and year of reign, official ROC documents use the Republic system of numbering years in which the first year was 1912, the year of the establishment of the Republic of China. Months and days are numbered according to the Gregorian calendar; the Gregorian calendar was adopted by the nascent Republic of China effective 1 January 1912 for official business, but the general populace continued to use the traditional Chinese calendar. The status of the Gregorian calendar was unclear between 1916 and 1921 while China was controlled by several competing warlords each supported by foreign colonial powers. From about 1921 until 1928 warlords continued to fight over northern China, but the Kuomintang or Nationalist government controlled southern China and used the Gregorian calendar.
After the Kuomintang reconstituted the Republic of China on 10 October 1928, the Gregorian calendar was adopted, effective 1 January 1929. The People's Republic of China has continued to use the Gregorian calendar since 1949. Despite the adoption of the Gregorian calendar, the numbering of the years was still an issue; the Chinese imperial tradition was to use the emperor's era year of reign. One alternative to this approach was to use the reign of the half-historical, half-legendary Yellow Emperor in the third millennium BC to number the years. In the early 20th century, some Chinese Republicans began to advocate such a system of continuously numbered years, so that year markings would be independent of the Emperor's regnal name; when Sun Yat-sen became the provisional president of the Republic of China, he sent telegrams to leaders of all provinces and announced the 13th day of 11th Month of the 4609th year of the Yellow Emperor's reign to be the first year of the Republic of China. The original intention of the Minguo calendar was to follow the imperial practice of naming the years according to the number of years the Emperor had reigned, a universally recognizable event in China.
Following the establishment of the Republic, hence the lack of an Emperor, it was decided to use the year of the establishment of the current regime. This reduced the issue of frequent change in the calendar, as no Emperor ruled more than 61 years in Chinese history — the longest being the Kangxi Emperor, who ruled from 1662–1722; as Chinese era names are traditionally two characters long, 民國 is employed as an abbreviation of 中華民國. The first year, 1912, is called 民國元年 and 2010, the "99th year of the Republic" is 民國九十九年, 民國99年, or 99. Based on Chinese National Standard CNS 7648: Data Elements and Interchange Formats—Information Interchange—Representation of Dates and Times, year numbering may use the Gregorian system as well as the ROC era. For example, 3 May 2004 may be written 2004-05-03 or ROC 93-05-03; the ROC era numbering happens to be the same as the numbering used by the Juche calendar of North Korea, because its founder, Kim Il-sung, was born in 1912. The years in Japan's Taishō period coincide with those of the ROC era.
In addition to the ROC's Minguo calendar, Taiwanese continue to use the lunar Chinese calendar for certain functions such as the dates of many holidays, the calculation of people's ages, religious functions. The use of the ROC era system extends beyond official documents. Misinterpretation is more in the cases when the prefix is omitted. There have been legislative proposals by pro-Taiwan Independence political parties, such as the Democratic Progressive Party to abolish the Republican calendar in favor of the Gregorian calendar. To convert any Gregorian calendar year between 1912 and the current year to Minguo calendar, 1912 needs to be subtracted from the year in question 1 added. East Asian age reckoning Public holidays in Taiwan
Edward III of England
Edward III was King of England and Lord of Ireland from January 1327 until his death. Edward III transformed the Kingdom of England into one of the most formidable military powers in Europe, his long reign of 50 years was the second longest in medieval England and saw vital developments in legislation and government, in particular the evolution of the English parliament, as well as the ravages of the Black Death. Edward was crowned at age fourteen after his father was deposed by his mother, Isabella of France, her lover Roger Mortimer. At age seventeen he led a successful coup d'état against Mortimer, the de facto ruler of the country, began his personal reign. After a successful campaign in Scotland he declared himself rightful heir to the French throne in 1337; this started. Following some initial setbacks, this first phase of the war went exceptionally well for England; this phase would become known as the Edwardian War. Edward's years were marked by international failure and domestic strife as a result of his inactivity and poor health.
Edward III was a temperamental man but capable of unusual clemency. He was in many ways a conventional king. Admired in his own time and for centuries after, Edward was denounced as an irresponsible adventurer by Whig historians such as William Stubbs; this view has been challenged and modern historians credit him with some significant achievements. Edward was born at Windsor Castle on 13 November 1312, was referred to as Edward of Windsor in his early years; the reign of his father, Edward II, was a problematic period of English history. One source of contention was the king's inactivity, repeated failure, in the ongoing war with Scotland. Another controversial issue was the king's exclusive patronage of a small group of royal favourites; the birth of a male heir in 1312 temporarily improved Edward II's position in relation to the baronial opposition. To bolster further the independent prestige of the young prince, the king had him created Earl of Chester at only twelve days of age. In 1325, Edward II was faced with a demand from his brother-in-law, Charles IV of France, to perform homage for the English Duchy of Aquitaine.
Edward was reluctant to leave the country, as discontent was once again brewing domestically over his relationship with the favourite Hugh Despenser the Younger. Instead, he had his son Edward created Duke of Aquitaine in his place and sent him to France to perform the homage; the young Edward was accompanied by his mother Isabella, the sister of King Charles, was meant to negotiate a peace treaty with the French. While in France, Isabella conspired with the exiled Roger Mortimer to have Edward deposed. To build up diplomatic and military support for the venture, Isabella had her son engaged to the twelve-year-old Philippa of Hainault. An invasion of England was launched and Edward II's forces deserted him completely. Isabella and Mortimer summoned a parliament, the king was forced to relinquish the throne to his son, proclaimed king in London on 25 January 1327; the new king was crowned as Edward III at Westminster Abbey on 1 February at the age of 14. It was not long before the new reign met with other problems caused by the central position at court of Roger Mortimer, now the de facto ruler of England.
Mortimer used his power to acquire noble estates and titles, his unpopularity grew with the humiliating defeat by the Scots at the Battle of Stanhope Park and the ensuing Treaty of Edinburgh–Northampton, signed with the Scots in 1328. The young king came into conflict with his guardian. Mortimer knew his position in relation to the king was precarious and subjected Edward to disrespect; the tension increased after Edward and Philippa, who had married at York Minster on 24 January 1328, had a son on 15 June 1330. Edward decided to take direct action against Mortimer. Aided by his close companion William Montagu and a small number of other trusted men, Edward took Mortimer by surprise at Nottingham Castle on 19 October 1330. Mortimer was executed and Edward III's personal reign began. Edward III was not content with the peace agreement made in his name, but the renewal of the war with Scotland originated in private, rather than royal initiative. A group of English magnates known as The Disinherited, who had lost land in Scotland by the peace accord, staged an invasion of Scotland and won a great victory at the Battle of Dupplin Moor in 1332.
They attempted to install Edward Balliol as king of Scotland in David II's place, but Balliol was soon expelled and was forced to seek the help of Edward III. The English king responded by laying siege to the important border town of Berwick and defeated a large relieving army at the Battle of Halidon Hill. Edward reinstated Balliol on the throne and received a substantial amount of land in southern Scotland; these victories proved hard to sustain, as forces loyal to David II regained control of the country. In 1338, Edward was forced to agree to a truce with the Scots. One reason for the change of strategy towards Scotland was a growing concern for the relationship between England and France; as long as Scotland and France were in an alliance, the English were faced with the prospect of fighting a war on two fronts. The French carried out raids on English coastal towns, leading to rumour
The Ethiopian calendar or Eritrean calendar is the principal calendar used in Ethiopia and serves as the liturgical year for Christians in Eritrea and Ethiopia belonging to the Eritrean Orthodox Tewahedo Church, Ethiopian Orthodox Tewahedo Church, Eastern Catholic Churches, the Coptic Orthodox Church of Alexandria, Ethiopian-Eritrean Evangelicalism. It is a solar calendar which in turn derives from the Egyptian calendar, but like the Julian calendar, it adds a leap day every four years without exception, begins the year on August 29 or August 30 in the Julian calendar. A gap of 7–8 years between the Ethiopian and Gregorian calendars results from an alternative calculation in determining the date of the Annunciation. Like the Coptic calendar, the Ethiopic calendar has 12 months of 30 days plus 5 or 6 epagomenal days, which comprise a thirteenth month; the Ethiopian months begin on the same days as those of the Coptic calendar, but their names are in Ge'ez. A 6th epagomenal day is added every 4 years, without exception, on August 29 of the Julian calendar, 6 months before the corresponding Julian leap day.
Thus the first day of the Ethiopian year, 1 Mäskäräm, for years between 1900 and 2099, is September 11. However, it falls on September 12 in years before the Gregorian leap year. Enkutatash is the word for the Ethiopian New Year in Amharic, the official language of Ethiopia, while it is called Ri'se Awde Amet in Ge'ez, the term preferred by the Ethiopian & Eritrean Orthodox Tewahedo Churchs, it occurs on September 11th in the Gregorian Calendar. The Ethiopian Calendar Year 1998 Amätä Məhrät began on the Gregorian Calendar Year on September 11th, 2005. However, the Ethiopian Years 1992 and 1996 began on the Gregorian Dates of'September 12th 1999' and'2003' respectively; this date correspondence applies for the Gregorian years 1900 to 2099. The Ethiopian leap year is every four without exception, while Gregorian centurial years are only leap years when divisible by 400; as the Gregorian year 2000 is a leap year, the current correspondence lasts two centuries instead. The start of the Ethiopian year falls on August 30th.
This date corresponds to the Old-Style Julian Calendar. This deviation between the Julian and the Gregorian Calendar will increase with the passing of the time. You can observe the real start date in the future centuries in a Gregorian to Ethiopian Date Converter. To indicate the year and followers of the Eritrean churches today use the Incarnation Era, which dates from the Annunciation or Incarnation of Jesus on March 25, AD 9, as calculated by Annianus of Alexandria c. 400. Meanwhile, Europeans adopted the calculations made by Dionysius Exiguus in AD 525 instead, which placed the Annunciation 8 years earlier than had Annianus; this causes the Ethiopian year number to be 8 years less than the Gregorian year number from January 1 until September 10 or 11 7 years less for the remainder of the Gregorian year. In the past, a number of other eras for numbering years were widely used in Ethiopia and the Kingdom of Aksum; the most important era – once used by the Eastern Christianity, still used by the Coptic Orthodox Church of Alexandria – was the Era of Martyrs known as the Diocletian Era, or the era of Diocletian and the Martyrs, whose first year began on August 29, 284.
Respective to the Gregorian and Julian New Year's Days, 31⁄2 to 4 months the difference between the Era of Martyrs and the Anni Domini is 285 years. This is because in AD 525, Dionysius Exiguus decided to add 15 Metonic cycles to the existing 13 Metonic cycles of the Diocletian Era to obtain an entire 532 year medieval Easter cycle, whose first cycle ended with the year Era of Martyrs 247 equal to year DXXXI, it is because 532 is the product of the Metonic cycle of 19 years and the solar cycle of 28 years. Around AD 400, an Alexandrine monk called Panodoros fixed the Alexandrian Era, the date of creation, on 29 August 5493 BC. After the 6th century AD, the era was used by Ethiopian chronologists; the twelfth 532 year-cycle of this era began on 29 August AD 360, so 4×19 years after the Era of Martyrs. Bishop Anianos preferred the Annunciation style as 25 March, thus he shifted the Panodoros era by about six months, to begin on 25 March 5492 BC. In the Ethiopian calendar this was equivalent to 15 Magabit 5501 B.
C.. The Anno Mundi era remained in usage until the late 19th century; the 4 year leap-year cycle is associated with the four Evangelists: the first year after an Ethiopian leap year is named the John-year, followed by the Matthew-year, the Mark-year. The year with the 6th epagomenal day is traditionally designated as the Luke-year. There are no exceptions to the 4 year leap-year cycle, like the Julian calendar but unlike the Gregorian calendar; these dates are valid only from March 1900 to February 2100. This is because 1900 and 2100 are not leap years in the Gregorian calendar, while they are still leap year
Ab urbe condita
Ab urbe condita, or Anno urbis conditæ abbreviated as AUC in either case, is a convention, used in antiquity and by classical historians to refer to a given year in Ancient Rome. Ab urbe condita means "from the founding of the City," while anno urbis conditæ means "in the year since the City's founding." Therefore, the traditional year of the foundation of Rome, 753 BC, would be written AUC 1, while AD 1 would be AUC 754. The foundation of the Empire in 27 BC would be AUC 727. Usage of the term was more common during the Renaissance, when editors sometimes added AUC to Roman manuscripts they published, giving the false impression that the convention was used in antiquity. In reality, the dominant method of identifying years in Roman times was to name the two consuls who held office that year. In late antiquity, regnal years were in use, as was the Diocletian era in Roman Egypt after AD 293, in the Byzantine Empire after AD 537, following a decree by Justinian; the traditional date for the founding of Rome, 21 April 753 BC, is due to Marcus Terentius Varro.
Varro may have used the consular list and called the year of the first consuls "ab urbe condita 245," accepting the 244-year interval from Dionysius of Halicarnassus for the kings after the foundation of Rome. The correctness of this calculation has not been confirmed. From the time of Claudius onward, this calculation superseded other contemporary calculations. Celebrating the anniversary of the city became part of imperial propaganda. Claudius was the first to hold magnificent celebrations in honor of the anniversary of the city, in AD 48, the eight hundredth year from the founding of the city. Hadrian and Antoninus Pius held similar celebrations, in AD 121, in AD 147 and AD 148, respectively. In AD 248, Philip the Arab celebrated Rome's first millennium, together with Ludi saeculares for Rome's alleged tenth sæculum. Coins from his reign commemorate the celebrations. A coin by a contender for the imperial throne, explicitly states "ear one thousand and first", an indication that the citizens of the empire had a sense of the beginning of a new era, a Sæculum Novum.
The Anno Domini year numbering was developed by a monk named Dionysius Exiguus in Rome in AD 525, as a result of his work on calculating the date of Easter. Dionysius did not use the AUC convention, but instead based his calculations on the Diocletian era; this convention had been in use since AD 293, the year of the tetrarchy, as it became impractical to use regnal years of the current emperor. In his Easter table, the year AD 532 was equated with the 248th regnal year of Diocletian; the table counted the years starting from the presumed birth of Christ, rather than the accession of the emperor Diocletian on 20 November AD 284, or as stated by Dionysius: "sed magis elegimus ab incarnatione Domini nostri Jesu Christi annorum tempora praenotare". Blackburn and Holford-Strevens review interpretations of Dionysius which place the Incarnation in 2 BC, 1 BC, or AD 1, it has been calculated that the year AD 1 corresponds to AUC 754, based on the epoch of Varro. Thus, AUC 1 = 753 BC AUC 753 = 1 BC AUC 754 = AD 1 AUC 1000 = AD 247 AUC 1229 = AD 476 AUC 2206 = AD 1453 AUC 2753 = AD 2000 AUC 2772 = AD 2019 List of Latin phrases
The Buddhist calendar is a set of lunisolar calendars used in mainland Southeast Asian countries of Cambodia, Laos and Thailand as well as in Sri Lanka and Chinese populations of Malaysia and Singapore for religious or official occasions. While the calendars share a common lineage, they have minor but important variations such as intercalation schedules, month names and numbering, use of cycles, etc. In Thailand, the name Buddhist Era is a year numbering system shared by the traditional Thai lunisolar calendar and by the Thai solar calendar; the Southeast Asian lunisolar calendars are based on an older version of the Hindu calendar, which uses the sidereal year as the solar year. One major difference is that the Southeast Asian systems, unlike their Indian cousins, do not use apparent reckoning to stay in sync with the sidereal year. Instead, they employ their versions of the Metonic cycle. However, since the Metonic cycle is not accurate for sidereal years, the Southeast Asian calendar is drifting out of sync with the sidereal one day every 100 years.
Yet no coordinated structural reforms of the lunisolar calendar have been undertaken. Today, the traditional Buddhist lunisolar calendar is used for Theravada Buddhist festivals, no longer has the official calendar status anywhere; the Thai Buddhist Era, a renumbered Gregorian calendar, is the official calendar in Thailand. The calculation methodology of the current versions of Southeast Asian Buddhist calendars is based on that of the Burmese calendar, in use in various Southeast Asian kingdoms down to the 19th century under the names of Chula Sakarat and Jolak Sakaraj; the Burmese calendar in turn was based on the "original" Surya Siddhanta system of ancient India. One key difference with Indian systems is that the Burmese system has followed a variation of the Metonic cycle, it is unclear from where, how the Metonic system was introduced. The Burmese system, indeed the Southeast Asian systems, thus use a "strange" combination of sidereal years from Indian calendar in combination with the Metonic cycle better for tropical years.
In all Theravada traditions, the calendar's epochal year 0 date was the day in which the Buddha attained parinibbāna. However, not all traditions agree on when it took place. In Burmese Buddhist tradition, it was 13 May 544 BCE, but in Thailand, it was 11 March 545 BCE, the date which the current Thai lunisolar and solar calendars use as the epochal date. Yet, the Thai calendars for some reason have fixed the difference between their Buddhist Era numbering and the Christian/Common Era numbering at 543, which points to an epochal year of 544 BCE, not 545 BCE. In Myanmar, the difference between BE and CE can be 543 or 544 for CE dates, 544 or 543 for BCE dates, depending on the month of the Buddhist Era. In Sri Lanka, the difference between BE and CE is 544; the calendar recognizes two types of months: sidereal month. The Synodic months are used to compose the years while the 27 lunar sidereal days, alongside the 12 signs of the zodiac, are used for astrological calculations; the days of the month are counted in two halves and waning.
The 15th of the waxing is the civil full moon day. The civil new moon day is the last day of the month; because of the inaccuracy of the calendrical calculation systems, the mean and real New Moons coincide. The mean New Moon precedes the real New Moon; as the Synodic lunar month is 29.5 days, the calendar uses alternating months of 29 and 30 days. Various regional versions of Chula Sakarat/Burmese calendar existed across various regions of mainland Southeast Asia. Unlike Burmese systems, Lan Na, Lan Xang and Sukhothai systems refer to the months by numbers, not by names; this means reading ancient texts and inscriptions in Thailand requires constant vigilance, not just in making sure one is operating for the correct region, but for variations within regions itself when incursions cause a variation in practice. However, Cambodian month system, which begins with Margasirsa as the first month, demonstrated by the names and numbers; the Buddhist calendar is a lunisolar calendar in which the months are based on lunar months and years are based on solar years.
One of its primary objectives is to synchronize the lunar part with the solar part. The lunar months twelve of them, consist alternately of 29 days and 30 days, such that a normal lunar year will contain 354 days, as opposed to the solar year of ~365.25 days. Therefore, some form of addition to the lunar year is necessary; the overall basis for it is provided by cycles of 57 years. Eleven extra days are inserted in every 57 years, seven extra months of 30 days are inserted in every 19 years; this provides 20819 complete days to both calendars. This 57-year cycle would provide a mean year of about 365.2456 days and a mean month of about 29.530496 days, if not corrected. As such, the calendar adds an intercalary month in leap years and sometimes an intercalary day in great leap years; the intercalary month not only corrects the length of the year but corrects the accumulating error of the month to extent of half a day. The average length of the month is further corrected by adding a day to Nayon