Sukuyo 27 vs 28 mansions: roster and table differences
Sukuyo 27 vs 28 mansions is a method choice. OpenFate omits 牛; adding it changes the roster and can shift later relationship positions.
Overview
Compare the presence of 牛 and the month-start row before comparing interpretations. A shared mansion name can conceal a different method.
At a glance
- Product roster
- 27
- Excluded from product sequence
- 牛
- Historical material
- Includes 28-mansion passages and tables
Compare the complete roster
Check whether 牛 appears between 斗 and 女. Do not decide the system only from familiar names such as 昴 or 角.
The same characters can appear in a Chinese astronomical account and a Japanese date-based reading with different rules.
Compare what the label measures
A date-table result and the Moon’s measured longitude are different outputs. Neither becomes equivalent merely because both use lunar-mansion vocabulary.
A source must state whether it assigns a day, a birth date or an observed celestial position.
Check the month-start table
T1299 volume one gives a first-day row beginning 虛室奎胃. OpenFate’s modern table begins 室奎胃畢.
This discrepancy is visible before any personality interpretation is attempted. Record it as a table difference.
Check relationship offsets
The three-nine arrangement has 27 positions. Adding an entry changes the positions reached by counting forward.
Do not combine a 28-entry roster with 27-entry relationship labels and call the result a validated hybrid.
Resolve a disagreement
Save each tool’s input, converted lunar date, roster and month-start rule. Locate the first step at which the results diverge.
A different result is not evidence that you have two personalities; it first indicates that the methods require comparison.
Check one offset before trusting a table
Choose a stated source mansion and count to a stated target with the printed roster. Repeat after inserting 牛 in its documented position.
If the offset changes, compatibility labels derived from that offset cannot be copied between the 27- and 28-entry tables.
Sources and editorial basis
- 宿曜經 · T1299 卷上卷上「宿曜曆經序分定宿直品第一」and「大唐月建圖」: 牛 and differing month-start row.Historical text for mansion names and calendar tables. Its table is not identical to OpenFate’s modern 27-mansion lookup; it does not establish predictive validity.
- OpenFate Sukuyo calculator and calculation conventionEditorial code check 2026-09-10, policy 1.0.0: 27-vs-28; policy.ts, constants.ts, engine.ts and traditional-cycles.ts. Product settings are not an independent historical authority; practical examples are OpenFate editorial applications.Product-specific input and output reference. Editorial checks also inspected policy 1.0.0 and the month-start constants on 2026-09-10; those implementation checks are not an independent traditional authority.