Burmese calendar

Origin The Burmese chronicles trace the origin of the Burmese calendar to ancient India with the introduction of the Kali Yuga Era in 3102 BCE. That seminal calendar is said to have been recalibrated by King Añjana (), the maternal grandfather of the Buddha, in 691 BCE. That calendar in turn was recalibrated and replaced by the Buddhist Era with the starting year of 544 BCE. The Buddhist Era came to be adopted in the early Pyu city-states by the beginning of the Common Era. Then in 78 CE, a new era called the Shalivahana era, also called Sakra Era or Saka Era, was launched in India. Two years later the new era was adopted in the Pyu state of Sri Ksetra, and the era later spread to the rest of the Pyu states. According to the chronicles, the Pagan Kingdom at first followed the prevailing Saka Pyu Era, but in 640 CE King Popa Sawrahan (r. 613–640) recalibrated the calendar, naming the new era Kawza Thekkarit ( ) with a Year Zero starting date of 22 March 638 CE. It was used as the civil calendar, while the Buddhist Era remained in use as the religious calendar. Scholarship accepts the chronicle narrative regarding the North Indian origin of the calendar and the chronology of adoption in Burma up to the Mahāsakaraj Era. Recent research suggests that the Gupta Era (epochal year of 320 CE) may also have been in use in the Pyu states. Mainstream scholarship, however, holds that the recalibrated calendar was launched at Sri Ksetra, and later adopted by the upstart principality of Pagan. Spread The adoption by an ascendant Pagan paved the way for the calendar's adoption elsewhere in the Pagan Empire between the 11th and 13th centuries. The calendar first came to be used in peripheral regions or neighbouring states such as Arakan in the west and various Shan states in modern northern Thailand and Laos in the east, which adopted the calendar alongside folklore connected with the Burmese New Year. According to the Chiang Mai Chronicles and the Chiang Saen Chronicles, Chiang Mai and Chiang Saen and their tributary states of middle and upper Tai country (except Lamphun and Sukhothai) submitted to King Anawrahta and adopted the calendar in the mid-11th century in place of Mahāsakaraj, the standard calendar of the Khmer Empire. However, scholarship says the earliest evidence of Burmese calendar in modern Thailand dates only to the mid-13th century. While the use of the calendar appears to have spread southward to Sukhothai and eastward to Laotian states in the following centuries, The Siamese adoption turned out to be the main catalyst for the calendar's usage in Cambodia, a periodic vassal of Siam between the 16th and 19th centuries. Likewise, the calendar spread to the Chittagong region of Bengal, which was dominated by the Arakanese Mrauk-U Kingdom from the 15th to 17th centuries. One key difference from Indian systems was that the Burmese system followed a 19-year intercalation schedule (Metonic cycle). It is unclear from where, when or how the Metonic system was introduced; hypotheses range from China to Europe. The Burmese system thus uses a "strange" combination of sidereal years from the Indian calendar with the Metonic cycle, which is better for tropical years than sidereal years, so necessitating intercalation adjustments to reconcile the differences. Furthermore, the Burmese system did not incorporate advances in Indian calculation methods of the sidereal year until the mid-19th century. (The original Thuriya Theiddanta system is 0.56 second a year slower (and more accurate) than later Indian systems.) The earliest attempts on record to change the calendar were superficial. On the 800th anniversary of the calendar (29 March 1438), King Mohnyin Thado recalibrated the calendar to Year 2 (with Year Zero beginning on 18 March 1436). But the king died just over a year after the launch, and the new era died out a few years later. The next proposed change came in March 1638 from King Prasat Thong of Siam who in preparation of the upcoming millennial anniversary (10 April 1638) wanted to make a change to the governing animals of the months. As the practice was not prevalent in Burma, the proposal was rejected by King Thalun. Meanwhile, the growing cumulative discrepancy between the civil solar and luni-solar years attracted increasing attention. In the 1100th anniversary year (1738 CE) a new system of calculation was proposed that aimed to correct the errors of the original system, but the Toungoo court did not take any action. The present Surya Siddhanta (i.e., Saura school) was introduced to the Konbaung court in 1786, and was translated into Burmese after about 50 years. Finally, a new system called Thandeikta was proposed by Nyaunggan Sayadaw, a Buddhist monk, in Year 1200 (1838 CE). The new system was a hybrid between the original and the updated Surya schools. Unlike the new Surya, Thandeikta does not adopt the system of apparent reckoning; mean years and mean months are still used. It also retains the practice of placing the intercalary month always next to Waso and the intercalary day always at the end of Nayon, and only in a year which has an intercalary month. But Thandeikta follows the new Surya in small alterations of the length of the year and the month. The prevailing Metonic schedule was modified, and intercalary months were so fixed as to prevent further divergence between the solar and luni-solar years. With the support of Princess Sekkya Dewi, who later became the chief queen of King Mindon, the new system was fully adopted in 1853. The first adjustment to then existing Metonic Cycle was made by putting an intercalary month in 1201 ME (1839 CE) instead of 1202 ME (1840). As a result, the calendar has kept on drifting away from the actual solar year. The calendarists have periodically resorted to modifying its intercalation schedule, based on apparent reckoning, to keep pace, at the expense of making publishing future calendars more than a few years out all but impossible. In sum, at various times the calendar has used at least three slightly different methods of calculation to determine the insertion times of the intercalary day and month. Current status The calendar fell out of official status in several mainland Southeast Asian kingdoms (except Burma) in the second half of the 19th century with the arrival of European colonialism. The Gregorian calendar replaced the Burmese calendar in Cambodia in 1863 and Laos in 1889. In 1889, the only remaining independent kingdom in Southeast Asia, Siam, also replaced the Burmese calendar and switched to the Gregorian calendar as the official civil calendar and the Ratanakosin Era (with 1782 CE as Year 1) as the traditional lunisolar calendar. ==Structure==

Day The calendar recognises two types of day: astronomical and civil. The mean Burmese astronomical day is from midnight to midnight, and represents 1/30 of a synodic month or 23 hours, 37 minutes and 28.08 seconds. The civil day comprises two halves, the first half beginning at sunrise and the second half at sunset. In practice, four points of the astronomical and civil day (sunrise, noon, sunset, and midnight) were used as reference points. The civil day is divided into 8 baho ( ) (3 hours) or 60 nayi ( ) (24 minutes), each baho equalling 7.5 nayi. In the past, a gong ( ) was struck every nayi while a drum ( ) and a large bell ( ) were struck to mark every baho. Although the popular usage never extended beyond baho and nayi measurements, the calendar consists of time units down to the millisecond level. Only the following are used in calendrical calculations: Therefore, modern time units can be expressed as: Week The civil week consists of seven days. It was also customary to denote the day of the week by its preassigned numerical value between zero and six. The names Taninganwe (Sunday) and Taninla (Monday) are derived from Old Burmese but the rest from Sanskrit. } Month The calendar recognises two types of months: synodic month and sidereal month. (The calendar also recognises a solar month called Thuriya Matha, which is defined as 1/12th of a year. But the solar month varies by the type of year such as tropical year, sidereal year, etc.) The days of the month are counted in two halves, waxing ( ) 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 (14th or 15th waning). The mean and real (true) New Moons rarely coincide. The mean New Moon often precedes the real New Moon. In great leap years, the month of Nayon gets an extra intercalary day called yet-lun () or yet-ngin () and has 30 days. As such, the calendar adds an intercalary month ( ) in leap years ( ) and sometimes also an intercalary day ( ) in great leap years ( ). The intercalary month not only corrects the length of the year but also 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 at irregular intervals—a little more than seven times in two cycles (39 years). The intercalary day is never inserted except in a year which has an intercalary month. Both systems arrive at the same number of days in a 19-year cycle however. Furthermore, in contrast to Indian calendars, the Burmese calendar follows a Metonic cycle in which intercalary months are inserted on a set schedule. However, because the Burmese calendar has to adjust for the use of Indian-calendar-derived sidereal years with the Metonic cycle's tropical years, maintaining a set Metonic cycle has been a challenge. New Year's Day Since the main purpose of the Burmese calendar is to keep pace with the solar year, the new year is always marked by the solar year, which falls at the time when the Sun enters Aries. As a result, the New Year's Day of the Burmese calendar does not have to fall on the first day of the first month of Tagu; in fact, it almost never does fall on the first waxing of Tagu. Tagu is almost always divided into two parts Hnaung Tagu ( ; "Late Tagu"), before the New Year's Day and Oo Tagu ( ; "Early Tagu") on and after the New Year's Day. In some years, the year was so behind the solar year that the new year falls in Kason and both Hnaung Tagu and Hnaung Kason ( ; "Late Kason") exist. Therefore, just saying "Tagu of 1373 ME" is not complete as "Oo Tagu of 1373" corresponds to 2011 CE while "Hnaung Tagu of 1373" corresponds to 2012 CE. Cycle The calendar used to employ a 12-year Jovian cycle that redeployed the lunar month names and attached them to the years. The Burmese cycle is not the more familiar Jovian cycle of India with 60 years in it. The practice existed in the Pagan period but had died out by the 17th century. Epoch Burmese tradition recognises the following eras. The Buddhist Era and Kawza Era are still in use in Myanmar. ==Accuracy==

The Burmese calendar uses lunar months but tries to keep pace with the solar year. The present Thandeikta system's solar year is about 23 minutes 51.43 seconds ahead of the actual mean tropical year of 365.241289 days. The older Makaranta system was actually slightly more accurate, with 23 minutes 50.87 seconds ahead of the actual year. Burmese calendarists have dealt with the issue by using apparent reckoning and periodically modifying the intercalation schedule in the Metonic cycle. One major downside of this approach is that it is difficult to publish future calendars more than a few years (often even a year) ahead. ==Zodiac==

Seasons The Burmese zodiac, like the Western zodiac, is divided into 12 signs called yathi ( ). The Burmese signs are identical to Indian and Western signs as they were derived from Indian and ultimately Western zodiac. Each yathi is divided into 30 degrees ( ); each degree into 60 minutes ( ); and each minute into 60 seconds ( ). Lunar mansions The zodiac month consists of 27 days, approximating the mean sidereal month of 27.321661 days. Thus each zodiac day, called nekkhat, represents a lunar mansion, or a segment of the ecliptic along which the Moon revolves around the Earth. Though the names are Burmese adaptations of Sanskrit names, the Burmese system is not the same as the modern Indian system. The Burmese system uses unequal spaces for each segment (from 5° to 26°), and the first segment, Athawani, begins at 350° longitude. The modern Indian system uses equal segments of 13° 20' (360° divided by 27), and the first segment, Asvini, begins at 0°. The list below follows the Thandeikta system. Weekdays The Burmese zodiac recognises eight signs in a seven-day week. ==Variants==

The Burmese calendar has a number of variants inside present-day Myanmar as well as outside. The variants outside Myanmar are still in use albeit under a different year numbering system. Arakanese According to Arakanese (Rakhine) tradition, the calendar was launched by King Thuriya Thehta of the Dhanyawaddy dynasty. At least down to the early 20th century, the Arakanese calendar used the Makaranta system although the Burmese calendar had moved to the Thandeikta system since the mid-19th century. In the Arakanese calendar, the month of Tagu gets the extra intercalary day in great leap years. The Arakanese calendar under the name of Magi-San is still used by the Magh people of Bangladesh and Tripura in India. This means reading ancient texts and inscriptions in Thailand requires constant vigilance, not just in making sure one is correctly operating for the correct region, but also for variations within regions itself when incursions cause a variation in practice. The practice also existed in Burma in the Pagan period but later died out. Lastly, the calculation methods also diverged in the mid-19th century when the Konbaung dynasty switched to the Thandeikta method, which is 0.56 second per year longer than the old system. Dai The traditional Dai calendar of Dai people of the Xishuangbanna in China is largely based on the Burmese calendar although it may have some Chinese influences. ==Current usage==

Public holidays The Burmese calendar is still used to determine a number of public holidays in Myanmar. Date of birth In Myanmar, people may register their date of birth in a Gregorian or Burmese calendar format. Official formats The Burmese language versions of official pronouncements by the government such as laws, notifications, documents are dated in both Burmese and Western (Gregorian) forms. The Burmese calendar date comes first, and is followed by the equivalent Gregorian calendar date in parentheses, both in the Year-Month-Day order. For example, the date of 29 March 2017 is written as: () ==See also==