Midheaven and meridian intersection
What the MC geometrically represents and why it is not always the highest ecliptic point or the tenth whole-sign cusp.
Calculation contract · released 2026-08-18
Definition
The Midheaven is the ecliptic intersection with the local meridian selected for the upper culmination direction.
Calculation procedure
Use local sidereal time and obliquity in the declared ecliptic/equatorial frame, solve the meridian intersection, and select the upper branch.
Required inputs
- Instant and Earth-rotation model
- Observer longitude
- Obliquity and frame convention
Maha convention
Maha documents the MC as a separate angle; the current production natal report does not use it to redefine whole-sign house ten.
Uncertainty and edge cases
At high latitudes the MC can fall far from the tenth whole-sign sector, and careless quadrant assumptions can mislabel it.
What this does not establish
The MC’s calculation does not establish a career, status, or corporate outcome.
Authoritative references
These sources establish the calculation vocabulary, data product, or transformation convention. They do not establish astrological interpretation.
- 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.
- Swiss Ephemeris general documentation
Astrodienst AG · 2.10 documentation, checked 2026-08-18
An independent ephemeris implementation, supported reference choices, house calculations, and its dual-license boundary.
Boundary: Maha does not bundle or call Swiss Ephemeris in production. Frozen conformance results are validation evidence, not permission to redistribute its software or data.