Vimśottarī daśā eligibility and opening balance
Why the implemented Vimśottarī chronology belongs to a declared Lahiri-Jyotiṣa model and is not blended into tropical timing output.
Frame comparison · released 2026-08-18
Shared fact substrate
The input instant and Moon ephemeris state are shared. The 120-year sequence is a traditional timing convention rather than an astronomical cycle discovered from the ephemeris.
Required shared inputs
- Birth or event instant
- Moon tropical longitude
- Lahiri ayanāṁśa
- Nakṣatra position
- Daśā year-length convention
Tropical view
The tropical model does not receive a Vimśottarī period merely because it has a Moon longitude. A tropical timing method must be declared and calculated under its own rules.
Lahiri-sidereal view
The Lahiri Moon identifies the janma nakṣatra and elapsed fraction, which determine the opening mahādaśā and remaining balance under the versioned Jyotiṣa method.
Where they agree
Both models retain the same underlying Moon and birth-time provenance, including uncertainty that may affect a boundary-sensitive result.
Where they disagree
They disagree on technique eligibility, not merely labels. Only the declared sidereal model produces this daśā timeline in the current system.
Preservation policy
Namespace Vimśottarī features as Jyotiṣa/Lahiri, retain the Moon conversion and balance arithmetic, and mark any tropical model’s corresponding field not applicable.
Prohibited synthesis
Do not use tropical sign interpretations to explain a sidereal daśā result or present the absence of a tropical Vimśottarī output as evidence against tropical astrology.
What empirical comparison requires
Treat tropical and sidereal outputs as separate candidate models. Any performance claim requires preregistered features, outcomes, horizons, baselines, model-selection policy, multiplicity control, and prospective scoring that retains misses and abstentions.
Method sources
These sources define calculation and namespace policy. They do not determine which astrology system is true.
- Celestial timing reference library
Maha Celestial
Frame-explicit ingress, station, lunation, repeated-crossing, and Vimśottarī chronology conventions.
Boundary: A deterministic event date is not evidence that the event predicts a real-world outcome.
- Lahiri ayanāṁśa calculations
Maha Celestial
Maha’s declared transformation from retained tropical longitude to a separate Lahiri-sidereal longitude.
Boundary: Selecting Lahiri defines one sidereal convention; it does not establish that sidereal astrology is superior or empirically valid.
- Astrology tradition registry
Maha Celestial
Named, versioned rule namespaces and the separation between source provenance and empirical support.
Boundary: A well-sourced traditional rule remains an unvalidated interpretive claim unless separately tested.