Classical Mansion System
古宿制
The original historical system of 28 Lunar Mansions using ancient fixed degrees without precession correction.
The Classical Mansion System (古宿制) refers to the 28 Lunar Mansions as recorded in their original historical positions — the mansion boundaries established in classical texts such as the *Huainanzi* (《淮南子·天文訓》, c. 139 BCE) and the *Book of Han* (《漢書·律曆志》, c. 104 BCE) — without adjustment for stellar precession.
Practitioners using the Classical Mansion System work with mansion boundaries fixed at the values recorded in the historical canon, treating the ancient astronomical framework as the authoritative reference regardless of precession drift over centuries.