Sukuyo birth time: does the date-only method need it?
Sukuyo birth time is not an input in OpenFate policy 1.0.0, which uses a birth date, Asia/Tokyo, and a civil-midnight boundary.
Overview
A date-only birthday is not an exact birth instant. Preserve uncertainty instead of supplying an invented time to the lookup.
At a glance
- Birth time
- Not an input in policy 1.0.0
- Calendar timezone
- Asia/Tokyo
- Day boundary
- Civil midnight
Date-only input is a real constraint
A birthday field provides a civil date. It is not a complete timestamp from which every overseas birth instant can be reconstructed.
Do not invent a time or timezone to make a date-only input appear more precise.
Midnight is not three in the morning
The product rule explicitly names civil midnight. A source using another rollover needs a separate comparison.
Adding three hours without a declared method changes the input rather than improving it.
Overseas birthdays
Preserve the date documented in the birth record and follow the tool’s stated input instructions.
If a method requires conversion of an exact birth instant, it must request the necessary time and timezone. This date-only method does not secretly do so.
Uncertain dates near midnight
If the recorded birthday itself is uncertain between two dates, compare those two dates as alternatives.
Matching descriptions cannot recover the missing time. Keep the result conditional.
When exact time belongs to another method
A degree-based Moon or nakshatra calculation can require a precise instant and coordinate convention.
Do not transfer that requirement into Sukuyo’s date table or claim that the date table has calculated the exact lunar longitude.
Decide which uncertainty matters
If the civil birthday is certain, adding an approximate clock time contributes nothing to this date-only lookup. If the recorded date itself could be either side of midnight, calculate both candidate dates.
Report two conditional mansions when they differ; choosing the more flattering description would hide the unresolved input.
Sources and editorial basis
- 宿曜經 · T1299 卷上卷上「大唐月建圖」: calendar lookup; product date-only input and day boundary are separately verified settings.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: birth-time; 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.