Indian national calendar
When India gained its independence in 1947, a single federal state had to be created out of the many individual states. Among other things, a uniform calendar should also contribute to this. A calendar reform committee was set up, which analyzed more than 30 different calendars in its report and then worked out the national calendar. The new calendar should:
- be free from colonial influences.
- be free from Islamic influence.
- can be accepted in all states.
- show Indian origin.
- The year is a tropical year .
- The year begins at the time of the spring equinox .
- The common year consists of 365 days, the leap year of 366 days.
- The leap day is added to the first month.
The year count
The years are counted consecutively after the Saka era (AS). This count builds on the old era, which counts completed years and was already used by Indian astronomers with the epoch (1st Chaitra 0 AS) 15 March 78 AD or day 1749621 Julian count.
The beginning of the year
The year begins at the spring equinox with the month of Chaitra.
The year has a length of 365 days. However, since the tropical year currently has a length of 365.242177 days, an additional leap day has to be inserted about every four years in order to match the seasons. In the leap year, the month of Chaitra is extended by 1 day to 31 days. The leap years are linked to the leap years of the Gregorian calendar. Add 78 to the Indian year number and apply the switching rules of the Gregorian calendar: Leap years are all years whose year number is divisible by 4 without a remainder, with the exception of full centuries; these are only leap years if the year is divisible by 400 without a remainder. The following table shows which dates in the Indian national calendar are shifted in the leap year compared to the Gregorian calendar:
|Common year||Leap year|
With a length of 146097 days in 400 years, the calendar is mathematically 0.123792 days longer than 400 tropical years of length 365.24219052 (beginning of 2000) and would therefore shift by one day in around 3200 years compared to the astronomical beginning of spring.
The beginning of the month
The month begins roughly with the entry of the sun into a new zodiac sign.
The length of the month
Since the orbit of the earth around the sun is an ellipse, the sun needs different lengths of time for the individual signs of the zodiac in its apparent course through the ecliptic. In 1950 the times were as follows:
|Zodiac signs||Sun 1950
in the zodiac
The length of the individual months was derived from these values.
The month names
The names of the months are traditional month names of the lunar calendar. The individual months of the year have the following names and number of days:
|Sanskrit||transcription||in common year||in leap year|
The days of a month are counted from 1 to 30 or 31.
The week division is of Babylonian-Greek origin. The seven days of the week are called:
- Lance Latham: Standard C Date / Time Library. Programming the world's calendars and clocks . R & D Books, Lawrence KS 1998, ISBN 0-87930-496-0 , p. 314 ff.
- Lance Latham: Standard C Date / Time Library. Programming the world's calendars and clocks . R & D Books, Lawrence KS 1998, ISBN 0-87930-496-0 , p. 314.