Light time, aberration, and gravitational deflection
Why corrected sky positions require more than a target vector and why each correction must be declared independently.
Calculation contract · released 2026-08-18
Definition
Light time accounts for propagation delay; stellar aberration accounts for observer velocity; gravitational deflection accounts for light-path bending in gravitational fields.
Calculation procedure
Compute or retrieve the state under a documented correction sequence and retain applied/not-applied flags for each effect.
Required inputs
- Target and observer states
- Observation epoch
- Light-time iteration policy
- Aberration and deflection model
Maha convention
The celestial fact schema has separate fields for light time, stellar aberration, gravitational deflection, and atmospheric refraction.
Uncertainty and edge cases
A single label such as “corrected” is insufficient because providers group effects differently.
What this does not establish
A physically corrected coordinate has no greater empirical support as an astrological predictor.
Authoritative references
These sources establish the calculation vocabulary, data product, or transformation convention. They do not establish astrological interpretation.
- Horizons System Manual
NASA/JPL Solar System Dynamics · 4.98d (2025-11-21)
Solar-system object identifiers, observing centers, time inputs, reference frames, corrections, output quantities, and stated ephemeris limitations.
Boundary: Horizons output is authoritative only with the complete query contract preserved; transformed or rounded values require their own provenance record.
- Standards of Fundamental Astronomy
International Astronomical Union SOFA Board · 2023-10-11
IAU-approved algorithms for astrometry, time scales, Earth rotation, precession, nutation, coordinate transformations, and related fundamental astronomy.
Boundary: SOFA supplies standard algorithms and validation programs; an implementation must still record its exact release and input data products.