Sri Lanka Birth Chart & Lagna Calculator (Kendaraya / Handahana)

A kendaraya is a snapshot of the sky at the moment of birth, expressed in the sidereal (star-fixed) zodiac used across Sri Lanka. The calculation runs in seven deterministic steps, each drawn from a cited source rather than a lookup table:

1. Local time to UT. The birth clock time is converted to Universal Time by removing the Asia/Colombo offset in force on that date — normally +5:30, but +6:30 or +6:00 for births in the 1996–2006 window (and the 1942–1945 wartime window).
2. Julian Day and ΔT. The date becomes a Julian Day, and the Espenak–Meeus ΔT polynomial gives the Dynamical Time the lunar and planetary theories require.
3. Tropical longitudes.The Moon uses the Meeus truncated ELP-2000/82 series (Ch. 47). The Sun and the five classical planets use Schlyter's Keplerian orbital elements, solving Kepler's equation for each and shifting from heliocentric to geocentric coordinates; Jupiter and Saturn carry their principal mutual-perturbation terms. Rahu is the Moon's mean ascending node, and Ketu sits exactly opposite.
4. Sidereal conversion. Every longitude has the Lahiri (Chitra-paksha) ayanamsa subtracted, moving it from the tropical to the sidereal zodiac: λ_sidereal = (λ_tropical − ayanamsa) mod 360.
5. Ascendant (Lagna). The apparent sidereal time (Meeus Ch. 12) plus the birth east-longitude gives the RAMC; with the obliquity ε (Meeus Ch. 22) and geographic latitude φ, the ascendant is atan2(cos θ, −(sin θ·cos ε + tan φ·sin ε)) (θ = RAMC), then the ayanamsa is removed for the sidereal Lagna.
6. Sign, nakshatra and pada. Sign index = ⌊λ/30°⌋, nakshatra index = ⌊λ/13°20′⌋, and pada = ⌊(λ mod 13°20′)/3°20′⌋ + 1. An independent global-pada formula cross-checks every placement.
7. Vimshottari balance.The fraction of the Moon's nakshatra still to be traversed, times the nakshatra lord's period, gives the balance of the mahadasha running at birth; the remaining lords follow in the fixed 120-year order.

The tool computes a chart only — the Lagna, grahas, birth star and dasha. It offers no predictions, readings or dosha verdicts, and (in v1) no divisional charts beyond the Rasi (D1) and no house system beyond whole signs from the Lagna.

• Paul Schlyter — Computing planetary positions (Sun & planets, Keplerian elements)
• IANA Time Zone Database — Asia/Colombo historical UTC offsets
• Espenak & Meeus — ΔT polynomial expressions
• Lahiri (Chitra-paksha) ayanamsa — definition and drift rate

The Moon theory, Julian Day, ΔT and nakshatra resolution are reused from this site's birth-star name-letter tool, which is validated against Meeus Example 47.a. Astronomy engine last verified 2026-07-09. Sign placements are computed, not interpreted; near a cusp, confirm with an established Lahiri ephemeris.