Uranus direct and retrograde station reference
A reproducible definition of Uranus stations based on apparent geocentric ecliptic motion, with root finding, speed thresholds, and frame boundaries.
Timing reference · released 2026-08-18
Event definition
A Uranus station is the instant at which the time derivative of its unwrapped apparent geocentric ecliptic longitude changes sign. “Stationary” names a coordinate extremum; the body does not stop moving through physical space.
Reproducible calculation
Calculate Uranus longitude on a sufficiently fine time grid, unwrap the angular series, estimate longitudinal speed without crossing a 0/360-degree discontinuity, bracket each speed sign change, and refine the zero. Verify the before/after direction and retain the sampling and root tolerances.
Required inputs
- UTC search interval
- Uranus apparent geocentric longitude
- Ephemeris and correction profile
- Sampling step and station root tolerance
Maha convention
Maha records the primary station in apparent geocentric tropical ecliptic longitude as direct-to-retrograde or retrograde-to-direct. A sidereal derivative subtracts a time-varying ayanāṁśa and can shift the numerical zero slightly, so any sidereal station is labelled as a separate convention rather than a second physical stop.
Uncertainty and edge cases
Near zero speed, finite differencing, ephemeris precision, and a time-varying frame offset can create or shift a broad apparent plateau. The reported instant must include a tolerance or bracket; rounded daily positions cannot support minute-level station claims.
How reports may use this reference
Reports may show the station bracket, motion before and after it, and nearby ingress crossings. They may not convert “stationary” into strength, reversal, delay, or outcome language without a named, reviewed tradition rule.
What this does not establish
A Uranus station does not establish that plans reverse, decisions fail, communications change, or any future event becomes more or less likely.
Calculation and convention sources
Sources establish astronomical states or a declared chronology convention. They do not establish 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.
- 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.
- 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.