Ayanamsa is the Sanskrit term. Precision of equinoxes is the most popular translation to this word.
It is defined as the angle by which the sidereal ecliptic of a celestial body is less than its tropical ecliptic longitude.
The sidereal ecliptic longitude of a celestial body is its longitude on the ecliptic defined with respect to the “fixed” stars
The tropical ecliptic longitude of a celestial body is its longitude on the ecliptic defined with respect to the Vernal Equinox Point.
The angular distance between vedic first point and the vernal equinox is the ayanamsa
There are so many other definitions on Ayanmsa and so many values taken by different scholars at different times.
Ayanamsa Start Year
Lahiri 285 AD
B. V. Raman 397 AD
Krishnamurthi 291 AD
Yukteshwar 499 AD
Varahamihira, Bhaskara, Aryabhatt and other scholars used different values. Westerners do follow tropical zodiac sign. In Indian Vedic Astrology, the system of fixed stars is used. For all astrological and ceremonial purposes, Nirayana longitudes are used.
Horoscopes prepared basing on different ayanamsas reflect different planetary positions. At least 10 horoscopes with different planetary longitudes can be prepared for each individual.
A glance at the concept and values of Ayanmsa reveal that no scholar is ready to accept the other’s formula. What is the fate of amateur astrologers with this confusing system of ayanamsa? Even eminent astrologers face this problem while trying to give accurate predictions with timings.
Centuries ago, Varahamihira, Aryabhatt, Bhaskara and other eminent Indian Astronomers and Astrologers carried out elaborate research in finding out accurate ayanamsa. And they have fixed their own ayanmsas. And they have succeeded in giving accurate predictions. Their spiritual powers rather than science made wonders. We have to give due respect to the great souls for guiding us.
In the recent past say in 1950s, the Government of India appointed a committee headed by Sri Nirmala Chandra Lahiri, an eminent astronomer / astrologer who along with his team conducted elaborate experiments and fixed the base year as 285 AD. Some time around in 1970s Prof. Krishna Murthy, Madras (now Chennai) based astrologer has augmented and refined the system of Vedic Astrology and established principles which have become very prominent in India and abroad and called Krishna Murthy Paddathi (Krishna Murthy System). Prof. Krishna Murthy fixed the base year as 291 AD.
Very recently, some of the followers of Krishna Murthy System have arrived at new Ayanamsa called KP Straight Line Adjusted Ayanamsa.
With the above brief analysis we understand that the Ayanamsa cannot be fixed to some base year and there is every need to review the same once in at least ten years.
Now we have sophisticated technology and with the help of the same, it might be very easy to carry out the same once in ten years.
What astrologers and common man require is accuracy in predictions and more or less accurate timing of incidents.
Sruthi Astrology appeals to the community of Astronomers and Astrologers to take up elaborate research on this aspect and review the Ayanamsa once in ten years and publish the same for use by astrologers.