Lahiri ayanamsha: what it is, and its exact value today
The Lahiri (Chitrapaksha) ayanamsha is the officially standardized measure of the gap between the tropical and sidereal zodiacs, adopted by the Government of India's Calendar Reform Committee in 1956. Its value today is 24°13′49″ (24.2304°), computed with the Swiss Ephemeris — every kundli on Tarasetu subtracts exactly this from tropical positions to get sidereal ones.
Today: 24°13′49″ · Lahiri (Chitrapaksha) · Swiss Ephemeris
Modern ephemerides (including the Swiss Ephemeris) compute planetary positions in the tropical frame. To cast a sidereal chart, an ayanamsha — the accumulated precession since the epoch when the two zodiacs coincided — is subtracted from every longitude. Choose a different ayanamsha and every planet, the lagna and the dashas shift slightly; that is why stating which ayanamsha a chart uses is basic transparency.
Lahiri anchors the zodiac so that the bright star Chitra (Spica, α Virginis) sits at exactly 0° of sidereal Tula — which places the zodiac's starting point, 0° Mesha, directly opposite it. The name Chitrapaksha comes from that anchor. Nirmal Chandra Lahiri, a Kolkata astronomer and member of the Calendar Reform Committee, computed and championed this reckoning.
The Calendar Reform Committee (1952–1956, chaired by astrophysicist Meghnad Saha) was tasked with unifying India's dozens of regional calendars. Its report fixed the Chitrapaksha ayanamsha for the national calendar and the Indian Ephemeris; the Rashtriya Panchang and official almanacs have used it since 1957. Because official panchangs, most published kundli tables and the large Jyotish software packages all default to Lahiri, charts computed with it are comparable across sources — which is the practical reason Tarasetu uses it and says so on every chart.
| Value today (computed) | 24°13′49″ (24.2304°) |
|---|---|
| Annual growth (precession) | ≈ 50.29″ per year |
| One full degree of drift | ≈ every 71.6 years |
| Zodiacs coincided | c. 285 CE |
| Standardized | Calendar Reform Committee, Government of India, 1956 |
| Anchor | Chitra (Spica) at 0° sidereal Tula |
B.V. Raman's ayanamsha runs about 1°25′ behind Lahiri; the Krishnamurti (KP) ayanamsha about 6′ behind; Fagan–Bradley, used by Western siderealists, about 53′ ahead. A kundli is only comparable with another if both state — and share — the ayanamsha. Tarasetu prints "Sidereal · Lahiri" on every chart for exactly this reason.
The full sidereal-vs-tropical story: Sidereal vs tropical →
- What is the current value of the Lahiri ayanamsha?
- 24°13′49″ (24.2304°) today, computed with the Swiss Ephemeris. It grows by about 50.29 arc-seconds per year; this page recomputes it daily.
- Why do different Jyotish apps give slightly different planet degrees?
- Usually because they use different ayanamshas (Lahiri vs Raman vs KP), different ephemeris precision, or different house systems. A difference of up to about a degree and a half between apps is almost always the ayanamsha choice, not a calculation error.
- Who was Lahiri?
- Nirmal Chandra Lahiri (1906–1980), a Kolkata astronomer and calendar scientist, member of the Calendar Reform Committee, and publisher of the Indian Ephemeris and Nautical Almanac. The standard ayanamsha carries his name; its technical name is Chitrapaksha.
- Does Tarasetu let the AI adjust the ayanamsha?
- No. The ayanamsha and all positions are computed deterministically by the Swiss Ephemeris. The AI explains results; it never does — or adjusts — the math.