Lahiri ayanamsa: definition, variants and chart comparison

Lahiri is a widely used sidereal reference convention. Swiss Ephemeris documents multiple Lahiri-related definitions, so “Lahiri” alone may not identify an implementation completely. Record the software's exact option and version when reproducing a result.

An ayanamsa is an angular offset for a particular epoch. It is not a fixed number you can copy into every historical birth chart. The software should evaluate its definition at the requested instant.

Take an invented tropical longitude of 100° and an invented offset of 24°. Subtracting gives 76°, which lies at Gemini 16°. This is an arithmetic demonstration and not a current Lahiri value.

100° − 24° = 76°

If a second implementation uses an illustrative 24°01′ instead, its result is 75°59′. Most labels in this example remain unchanged, but a coordinate near a sign, nakshatra or pada boundary could receive a different label.

Do not round the offset before conversion when resolving a boundary. Compare full-precision coordinates first and presentation labels second.

A useful comparison record includes the original local birth time, converted instant, ephemeris version, observer convention, sidereal-mode identifier and output precision. A screenshot that says only “Lahiri chart” omits part of that record.

This guide does not claim that selecting Lahiri proves an interpretation or guarantees a more successful reading. It explains a computational choice. VEDIC.world chart observations should keep the selected convention available as context.

Continue with Lahiri versus Raman for a comparison procedure, or ephemerides to understand why positional data and a sidereal reference are separate settings.