Khmer Chhankitek Calendar - ប្រតិទិន​ចន្ទគតិ​ខ្មែរ - Upo

[Dhammañāṇa]

Not only for Cambodians, but generally interessting and used in the Dhamma - Vinaya Tradition which is common nearly forgotten or simply unknown. Very needed in regard of counting the Uposatha days.
Simple methods known by the elders till today.

Khmer Chhankitek Calendar - ប្រតិទិន​ចន្ទគតិ​ខ្មែរ

Cambodians use two types of calendars: the international calendar for civil purposes and the traditional calendar for religious purposes. Although called Chhankitek, which means lunar calendar, Khmer traditional calendar is a lunisolar calendar similar to some of the Hindu calendars and the Chinese calendar.

The goal of this research is to create a create a computer program that can display the Khmer calendar for different years. With the recently published Khmer books on Khmer calendar by Mr. Kim Soeun Roath (ksroath@yahoo.com) (ប្រតិទិនសុរិយគតិ-ចន្ទគតិ ពីគ.ស១៩០០ ដល់ គ.ស១៩៩៩ និង គ.ស២០០០ ដល់ គ.ស២០៩៩ ដោយ លោក រាត់ គឹមសឿន), the mechanics of the Khmer calendar system can be unveiled. The book "អត្តាឡើងស័កនិងមហាសង្ក្រាន្ត" by the same author also shows the calculation of the Khmer new year songkran.


Khmer Date Utility: Acient Way of Counting Age
Find animal year from your age:

The 12 orange dots are the different positions used in this method. The animal years are positioned for the year of Roka (2005). This varies from year to year. The current animal year starts at brown arrow (second knuckle of your pointing finger) and counts clockwise to the successive years. The green flower star is where you start if the age is at least 10 years old or else start at the blue star marked as 1 going counter clockwise.

    Start counting from the tip of the pointing finger (green flower star) clockwise every second position. You count just the multiple of ten such as 10, 20, 30, and 40 until it reaches the ten digit of a specific age. As an example, for 35, I would count 10, 20, and then 30.
    If the age is a multiple of ten, that was your final position. Or else continue from the current position by counting backward (counter clockwise) one position at a time until it reaches a specific age. So for the 35, from my early position, I count counter clockwise 31, 32, 33, 34, and then 35 arriving at the dot marked 11 Jor.
    The last step is to determine what animal belongs to that final position. Start counting the current year animal at the brown arrow *. Count clockwise until it reaches your final position. That is the birth animal year for that age.

*Notes: This method has been modified. The original method is to start positioning the year at the blue star (lowest point of your pointing finger). But this missed by one year; so to make it works I move the start position up to the brown arrow.



Find your age from the animal year:

Age  Count

10   10
20   8
30   6
40   4
50   2
60   12
70   10
80   8
90   6
100  4

This assumes that you have some idea of how old you are in a range of 10 years. Use the table on the right to determine how many count to use for a specific age.

    Use your multiple of ten of your age to determine the count. Example, for the age around 30, the count is 6.
    Start from your animal year and count to the successive animal year for the number of time found in step 1. Example, assume I was born on the year of Dog (Jor) and I am around 30. So I would count 6 times as Kaor, Jute, Chlov, Karl, Thos, and Rorng. Notice I didn't count Jor as 1 but count Koar, the next year instead.
    Now use your finger to keep track of the count, and continue until you reach the current year. The final count is added to your multiple of ten of your age. Example: Continue from step 2, I would count, Masagn as 1, Momee as 2, Momay as 3, Voke as 4, and Roka as 5. If the current year is Roka, then I stop here. There so I am 30 + 5 or 35 years old.

The following is a list of Khmer lunar months and the number of days:



 Since a lunar month is about 29.5 days, one lunar year is 354 days, which is shorter than the solar year by 11 days. Adjusting for this discrepancy, an extra month is added every two to three years. An extra day is also added to a particular year to maintain the synchronization.

A leap year can have an extra month or an extra day.

    A year with an extra day is called Chhantrea Thimeas (ចន្ទ្រាធិមាស) or Adhikavereak (អធិកវារៈ). This year has 355 days.
    A year with an extra month is called Adhikameas (អធិកមាស). This year has 384 days.

The extra leap-day occurs in the month of Jays (ជេស្ឋ) which has 30 days instead of the normal 29 days.

Unlike the Indian and Chinese calendar where any month can become leap months, Khmer leap month is always in the month of Ashad. Adhikameas has two months of Ashad (អាសាធ). The first month of Ashad is called Badhamasad (បឋមាសាធ) and the second month is called Thutiyasad (ទុតិយាសាធ). In the year of Adhikameas both Badhamasad and Thutiyasad months have 30 days making the number of days in that year totaling 384 days. Only one type of leap year can occur at a time. There is no year with both an extra day and an extra month as in the case for the Chinese calendar.

Day

Khmer lunisolar calendar counts the day by using Keit (កើត) and Roaj (រោច). Keit signifies that the moon is in its waxing phase. Keit is counted from a new moon to a full moon. The number is counted from one to fifteen incrementally. So the new moon is one Keit and the full moon is fifteen Keit. Then it continues with one Roaj. Roaj indicates that the moon is in its waning phase going from full moon to new moon. Depending on the number of days in that month, Roaj can go from one to fourteen for a 29-day month or one to fifteen for a 30-day month.

This counting system occurs consistently throughout each month and differs from the Indian lunisolar calendar where the date or tithi can skip a day depending on the moon phase. In both the Indian and Chinese calendar, the number of days per month varies from year to year.

[Dhammañāṇa]

As the site is done and not longer maintained, yet very useful, Atma started to reconstruct the previous gift here:

https://sangham.net/en/calender/khmer_chhankitek

Not sure if the calender tool can be integrated as well, as it was long time source for the Uposathas. Maybe Nyom Moritz has an eye on it.

[Moritz]

Not sure if the calender tool can be integrated as well, as it was long time source for the Uposathas. Maybe Nyom Moritz has an eye on it.

I will take a look at it. Should be not too difficult to fill the forum calendar with the Uposatha days by this method automatically. 

* Moritz currently in Romania on vacation, with the goal of finding enough seclusion here to read a meditation manual written by Upasaka Dmytro, and planning to continue for a short visit to Kyiv in three days.

[Dhammañāṇa]

Mudita

[Dhammañāṇa]

Atma saw that Nyom Moritz generously edited a little and on it, Atma came to mind "maybe the generous share" by Bhante Ariyadhammika , especialy the mathematics by Bhante Gambhiro , might help, even surely a if different pattern (methods) of determination of Uposathas, at least for ideas of astro-datas, in case of undertakings here.

https://forum.sangham.net/index.php?topic=971.msg20656#msg20656

[Moritz]

Thanks for the hint, Bhante.
I am still reading the text and trying to follow it.

I do not know which shares of explanations about Uposatha days by Bhante Ariyadhammika and Bhante Gambhiro Bhante is referring to.
But it would be surely interesting for me to look at it as well.

[Dhammañāṇa]

Bhante had shared some works, also by Bhante Hasapanno here (maybe more scientific that traditional) here attached (not brought into library yet): https://forum.sangham.net/index.php?topic=971.msg20781#msg20781 , Nyom Moritz , remembering that Bhante Gambhiro used many algorithms.

[Moritz]

Thanks Bhante. That is a lot to look at.
May take some time until I am clear about everything.

[Dhammañāṇa]

Thanks Bhante. That is a lot to look at.
May take some time until I am clear about everything.

As much as investigations make joy and release from lower one, Nyom.

[Dhammañāṇa]

As nearly another year, Atma thought to go on to prepare it manually again.

[Moritz]

I am sorry that I forgot about this.
My mind is too crowded with other stuff and I don't know how to clean it up anymore.

[Dhammañāṇa]

No problem Nyom.