Convert the instant before choosing a pillar
Civil time is the legal wall clock supplied with the birth record: its timezone and any daylight-saving rule belong to that record. Local mean solar time is a different convention. Atlas starts from the engine’s UT1 instant, then applies the location’s east-positive longitude at four minutes per degree. It does not treat a civil UTC offset as the longitude correction.
For a deliberately simple example, at 15° east the local mean-solar correction is +60 minutes from Greenwich UT1. Thus 12:00 UT1 becomes 13:00 local mean solar time in this calculation. The example isolates longitude; it does not infer a legal timezone, daylight-saving history, or a birthplace from that longitude.
What this BaZi row actually calculates
The explorer makes a local-mean-solar row for each of its two declared day boundaries, 00:00 and 23:00. It converts the fixed birth instant, derives the hour branch from the resulting displayed clock hour, and derives the day and hour stems from the selected cycle date. The comparison table is therefore a test of named conventions for one instant, not a correction of an uncertain recorded birth time.
A difference close to midnight or 23:00 can change the displayed clock date, the cycle day, and then a day or hour pillar. An unchanged row means only that these particular outputs agree for the supplied input. The current snapshot does not create a local-solar row for an unknown birth time.
Use a stated convention, not a claim of superiority
Use local mean solar time when a source, school, or comparison explicitly asks for a longitude-based mean clock. Keep the entered civil record alongside it, including its timezone and any repeated-hour choice. If another calculator gives different pillars, compare the resolved instant, longitude sign, clock convention, and day boundary before treating the characters as a disagreement in interpretation.
This option is an inspectable calendar convention within Atlas’s introductory Four Pillars method. It does not establish that local mean solar time is universally preferred in BaZi or Saju, and it does not supply strength, favorable elements, luck periods, or a complete judgement.
Word origin · etymology
Descriptive astronomical phrase.
Local specifies one longitude, mean specifies an averaged Sun, and solar identifies the Sun as the time reference.
How we know · epistemology
Longitude-based clock convention
Longitude sets the offset of a uniform solar clock from Greenwich. This can reproduce a stated historical time basis, but it does not include legal timezone changes or daylight saving and must not be substituted silently for civil time.
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