Basics & calculation
What a birth mansion is, how 27 and 28 mansion systems differ, and why calculation methods disagree.
2 articles
SU-002
27 or 28 lunar mansions: what is the difference?
Separate sky positions, month-table assignments and continuous calendar annotations. Compare the name lists, a 28-day counter and the missing anchor needed for a real date.
SU-001What are Sukuyō astrology and the birth mansion?
Distinguish a measured Moon position from a calendar-assigned birth mansion. Compare named sources, a month-table example and the settings needed to reproduce a result.