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3. Myanmar Year
The length of a solar year in the Myanmar calendar is defined as 1577917828/4320000 (365.2587565) days [Irwin, 1909]. It is denoted by SY .
SY=1577917828/4320000
The beginning of a year is obtained by adding that constant to the beginning of the previous year. The starting time of the Myanmar year zero is denoted by MO . Using these two constants, the beginning of any Myanmar year can be expressed by using the following equation.
ja=SY.my+MO
where my is the Myanmar year and ja is the Julian Date value of its starting time. Starting time of a few recent Myanmar years can be found in recently published calendars. Substituting a few known values in ja and taking average, MO is estimated as Julian Date 1954168.050623.
Example: Find the starting time of 1375 ME.
Solution:
my = 1375
ja = SY * 1375 + MO
= 365.2587565*1375+1954168.0506
= 2456398.8407875
Therefore its starting time in Julian Date is 2456398.8407875. The corresponding Gregorian date is found as 2013-Apr-16 08:10 am.
[Julian Date to Western Date Converter](https://yan9a.github.io/mcal/j2w.htm) can also be used for the conversion.
The Myanmar new year festival (the water festival) is called the Thingyan. A typical Myanmar calendar mentions the beginning of the year called the atat time and it is the end of the Thingyan. The starting time of the Thingyan is called the akya time. The length of the Thingyan currently recognized by Myanmar Calendar Advisory Board is 2.169918982 days ( 2days, 4 hours, 4 minutes and 41 seconds). When the time of ancient Myanmar kings, 2.1675 days (2 days, 4 hours, 1 min and 12 seconds) was used as the length of the Thingyan. Therefore, the akya time can be obtained by subtracting 2.169918982 days from the atat time. Before the new system by Myanmar Calendar Advisory Board (1312 ME, 1950 CE) , 2.1675 days should be subtracted from the atat time to obtain the akya time. The akya time in Julian date jk can be calculated as follows.
if (my >= 1312) thenjk=ja−2.169918982elsejk=ja−2.1675end if
The days in the Myanmar calendar begin at midnight [Irwin, 1901] p-7. The day on which the akya time falls is called the akya day and the corresponding day for the atat time is called the atat day. The days between the akya day and the atat day are called akyat days. Since the difference between the atat time and the akya time is more than 2 days, the number of akyat days can be 1 or 2 depending on how the atat day and the akya day fall. The day before the akya day is called the akyo day (the Thingyan eve). Since a part of the atat day is in old year and the other part in new year, the atat day is not called as new year's day. Only the day after the atat day is called new year's day. A calculator that produces beginning of year, the akya time, the akyo day, akya day(s), the akyat day, the atat day and the new year's day for any given Myanmar year in Gregorian date is found at the following link.
The javascript code that calculates the Thingyan is shown below.
//Calculate the Thingyan (Myanmar new year)
//input: (my -myanmar year)
//output: (ja: atat time, jk: akya time, da: atat day, dk: akya day)
function ThingyanTime(my) {
var SY=1577917828/4320000; //solar year (365.2587565)
var LM=1577917828/53433336; //lunar month (29.53058795)
var MO=1954168.050623; //beginning of 0 ME
var SE3=1312; //beginning of 3rd Era
ja=SY*my+MO; if (my >= SE3) jk=ja-2.169918982; else jk=ja-2.1675;
return {ja:ja,jk:jk,da:Math.round(ja),dk:Math.round(jk)};
}
On the other hand, Myanmar year that corresponds to a Julian Day Number can be obtained as follows.
my=⌊jd−0.5−MO/SY⌋
Only the day after the atat day is the new year day and it is the reason for subtracting 0.5 from the day number.
For example, we have known that Julian Day Number for 2000 January 1 is 2451545, the corresponding Myanmar year is (2451545-0.5-1954168.0506)/365.2587565= 1361.7098. Taking floor operation gives Myanmar year 1361.
The origin of the Myanmar calendar is the old Hindu calendar. Therefore, year in the Myanmar calendar is started counting from the start of an era called Kali Yuga. Some Myanmar kings reset the year number to zero. Therefore, the Kali Yuga year and the Myanmar year are different. The Kali Yuga year number can be obtained by adding 3739 to the Myanmar year.
ky=my+3739
where ky is Kali Yuga year and my is Myanmar year. The start of Kali Yuga in the Myanmar calendar is found to be 588465.560139 in Julian date.
kymyja=0=ky−3739=−3739=SY∗(−3739)+MO=588465.560139
Dershowitz mentions the start of Kali Yuga in the old Hindu calendar is Friday, January 23, -3101 (Gregorian) [Dershowitz, 2008]. The starting mid night of that day corresponds to 588465.5 in Julian date. Therefore, there is a few hours difference from the start of Kali Yuga in the Myanmar calendar. He also mentions that the start of the old Hindu lunisolar calendar is about one month (28.62294 days) earlier than the start of the Kali Yuga. But, in the Myanmar calendar, the start of calendar and the start of the Kali Yuga seem to be at the same time. The corresponding Gregorian date for Julian date 588465.560139 is Friday, January 23, -3101, 1:26:36 am. The reason for that time discrepancy is the time difference between the reference location for the old Hindu calendar (Ujjain) and the reference location for the Myanmar calendar. The time difference, 1 hour 26 minute and 36 seconds, is exactly the same as mentioned by Saya U Aye Win Kyaw in jotisa Vedic magazine [Nyein, 2014, p.190]. Nyein [Nyein, 2012] stated that the time difference between these two locations is 1 hour, 26 minutes and 53.52 seconds which is a few seconds different from our result. According to Baddanta Thadiya (Chairman, Myanmar Calendar Advisory Board), the reference location, Ujjain, was temporarily agreed to be at 76° 06' by board members. [Thadiya, 2010]. If the Julian date is denoted by jd and the the number of days started counting from Kali Yuga epoch is denoted by kd , their relationship is found as follow.
kd=jd−588465.560139
Typical Myanmar calendars usually mention the year in Buddhist Era (BE) also. The Buddhist Era began in 543 BC [Clancey, 1906]. The relation between Buddhist Era year and Myanmar year is as follow. The months and the days are same in the both calendars.
by=my+1182
where by is year in Buddhist Era and my is Myanmar year.