New Moon calculation reference
How Maha calculates the New Moon as conjunction in ecliptic longitude, preserving UTC, phase direction, event type, location dependence, and uncertainty.
Timing reference · released 2026-08-18
Event definition
The New Moon is defined by a Sun–Moon phase-angle condition centered on 0°. A New Moon is not automatically a solar eclipse; eclipse geometry also requires suitable lunar latitude and observer alignment.
Reproducible calculation
Search the continuous geocentric Sun–Moon phase angle for 0°, bracket the crossing, preserve waxing or waning direction, and refine the root to the declared tolerance. Retain the ephemeris, time scale, longitude convention, and software version.
Required inputs
- UTC search interval
- Geocentric Sun and Moon state
- Phase-angle and root convention
- Numerical tolerance and phase direction
Maha convention
Maha records the New Moon instant as celestial geometry before deriving tithi, zodiac position, local date, or a tradition label. Tropical and sidereal Moon labels may differ, while the underlying Sun–Moon phase event remains one astronomical event.
Uncertainty and edge cases
The phase root can differ with ephemeris, correction model, timescale, and numerical tolerance. Local calendar date additionally depends on timezone; a date without UTC and zone provenance is not reproducible.
How reports may use this reference
Reports may show the exact New Moon root, local rendering, zodiac-frame labels, and separation from nearby chart points. Symbolic language requires a separately reviewed rule and must remain distinct from the phase calculation.
What this does not establish
The New Moon does not establish a beginning, culmination, crisis, release, or event outcome, and it is not evidence that a chart predicts reality.
Calculation and convention sources
Sources establish astronomical states or a declared chronology convention. They do not establish predictive meaning.
- Astronomy Engine
Don Cross (cosinekitty) · 2.1.19
Locally computed planetary longitudes, moon phases, eclipses, and search primitives used by Maha’s deterministic calculation layer.
Boundary: Library output is a computed astronomical result. Its reproducibility does not validate a symbolic or predictive meaning.
- Horizons System Manual
NASA/JPL Solar System Dynamics · 4.98d (2025-11-21)
Time-indexed solar-system states, observer centers, coordinate frames, apparent corrections, and output quantities used to verify planetary event searches.
Boundary: Horizons establishes astronomical states only when the complete query contract is retained; it supplies no astrological interpretation.
- Standards of Fundamental Astronomy
International Astronomical Union SOFA Board · 2023-10-11 release
Standard astronomical time-scale, precession, nutation, Earth-rotation, and coordinate-transformation algorithms.
Boundary: A standard transformation still requires declared inputs, ephemeris data, frame, origin, corrections, and software release.