Civil, Standard, and Solar Time in Bazi
Distinguish recorded civil time, standard time, mean solar time and apparent solar time before assigning Bazi hour and day boundaries.
Overview
Civil time is the legal local clock shown on the birth record, including any daylight-saving or political adjustment. Standard time is the zone’s non-daylight base offset for the relevant period. Local mean solar time adds a longitude correction, while local apparent solar time also adds the date-dependent equation of time. These are distinct stages, not interchangeable labels. OpenFate preserves the civil input and applies any selected solar-time method only after historical zone resolution.
At a glance
- Civil time
- Legal local clock including effective rules
- Standard time
- Zone base time without seasonal advance
- Mean solar time
- Standard time corrected for longitude
- Apparent solar time
- Mean solar time plus equation of time
- Correct order
- Resolve zone before solar correction
- Audit requirement
- Retain the original civil input and method
Civil time records what the local legal clock displayed
Civil time is tied to a jurisdiction’s historical rules. It may include daylight-saving time, a changed UTC offset or a one-time political adjustment.
The same wall-clock reading can therefore represent different instants in different places or years. A Bazi calculator must resolve the location and date before treating the reading as a timeline instant.
- Keep the birthplace’s local date and time.
- Apply the rules effective on that historical date.
Standard time is not always the recorded civil time
Standard time normally means the zone’s base offset without a seasonal clock advance. During daylight-saving periods, civil time can be one hour or another legally defined amount ahead of that base.
Removing daylight-saving time manually before resolving the zone can double-correct the record. The time-zone database should determine the active offset first.
- Do not assume every summer shift is one hour.
- Do not subtract DST twice.
Mean and apparent solar time are separate corrections
Local mean solar time accounts for the birthplace longitude relative to the effective standard meridian. Local apparent solar time then incorporates the equation of time, which varies with the date.
Calling both values “true solar time” hides which formula was used. An auditable chart should expose the longitude correction and equation-of-time correction separately.
- Name the selected solar-time definition.
- Store each correction in minutes.
Use the selected final time consistently at boundaries
If the configured final time crosses an hour branch, solar date or declared Zi-hour day boundary, all affected pillars must be recalculated together.
A correction setting is a methodology choice, not an interpretive result. It cannot be enabled only when it produces a preferred chart or life narrative.
- Recompute every dependent pillar after a crossing.
- Compare methods without cherry-picking.
Sources and editorial basis
- U.S. Naval Observatory: The Equation of Time美國海軍天文台區分標準時間、地方平太陽時與地方視太陽時，並說明經度修正與均時差成分An official astronomical explanation of apparent solar time, mean solar time, longitude offsets, and the equation of time.
- IANA Time Zone DatabaseIANA 歷史規則把紀錄的民用鐘錯時間還原為確定瞬間，包含當時日光節約與法定偏移The maintained reference for historical local-time rules, UTC offsets, and daylight-saving transitions by location.
- OpenFate Editorial Methodology產品時間流程固定為 civil time → 歷史時區 → mean solar time → equation of time → apparent solar time，並保留每步分鐘值OpenFate separates deterministic chart calculation, traditional interpretation, and modern editorial explanation.