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II. Saka - Sunda (Sunda - solar calendar system)


2.1 History

The Sunda - solar calendar system named Saka (It sounds like India calendar: ‘Saka’, but I can give an explanation they are different in rules). Saka sunda calendar is a truly astronomical observation calendar. Karuhun Sunda (Ancient Sundanese) made a media to observe the relation between time marking and the Sun. They used lingga (a stone column) which a restricted area for ordinary people, because it should kept precise. Later, several historian wrote that lingga were taboo place. Lingga used to measure shadows caused by sunray either north or southly. My hypotheses are, they measured it day by day with harupat (a kind of stick from plants), and then cut it as long as shadow’s length. They collected them sequentially. They had done it for very long time, until they found enough data to analyze, and then made a conclusion. Sundanese use this solar calendar in relation with seasons, planting and farming.


2.2 Rules

The year ended when the Sun on the maximum south point (23.5o South Latitude). They are two types of year in saka sunda calendar, a common year (365 day per year) and a leap year (366 day per year).

  1. The common year fall on years which undivisible by 4 (1,2,3,5,6,7,9,10,11,13,…)
  2. The leap year fall on years which divisible by 4 (4,8,12,16,...)
  3. But when that leap year fall on a year which divisible by 128 (128, 256, 512,...). It should not be a leap year, even it’s divisible by 4 (It should be a common year with 365 day per year).

With those rules we can make an accuration study;

Number of days in 128 years period = (128 x 365) + (128 / 4) - 1 = 46751days


128 x 365 = number of common year’s day in 128 years

128 / 4 = number of day that added (in leap year) in 128 years

-1= exception for year 128 (rules no. 3)

Then we can count an average age or length of year:

46751 days / 128 years = 365.2421875 days/year


(Notes: Because there are many new versions of 'Tropical year' numbers, and I still making a study of it, you can skip this section (24-08-98):

When I made this research, I used an astronomical tropical number 365.2422 days/year. Then we can count the missing day in a year; 365.2422 - 365.2421875 = 0.0000125 day per year

This number will be as many as 1 day in 80000 years. It means also, if we return the rule for year 80000 to a leap year (even it divisible by 128 (we ignored ruleNo.3)), we miss nothing in 80000 years long.

I found the new ‘tropical year’ in the Internet (in websites written by Peter Meyer). It is 365.24218967 (I round it to 365.2421897) days. If we use these number, Saka-Sunda calendar miss just 0.0000022 day per year. It is amazingly accurate, because It does not need an intercalating any more, this number is almost nothing in term of day unit. In another words, we will need just ‘1 day’ addition in year 454,545.4545. So, the judgement day will come earlier rather than an expiry date of this calendar! (jokes)


 2.3 Months



Go to:

I. Introduction

III. Caka Sunda Calendar (Sunda - lunar calendar system)

V. Mataram Javanese Calendar

IV. Conclusion


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