True Solar Time

True solar time correction and solar-corrected BaZi / Four Pillars casting — historical DST, longitude and equation of time, with hour-branch boundary…

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What it can do

  • True Solar Time: Convert a recorded birth time (wall clock + IANA time zone + longitude) into true solar time — the time a BaZi / Four Pillars chart should actually be cast from. Returns the corrected
  • Hour Branch: Which two-hour branch (子丑寅卯…) a given time falls in, and minutes to the nearest branch boundary. Use on an already-corrected time; for raw birth records use true_solar_time.
  • Cast Pillars: Cast a BaZi / Four Pillars chart the right way round: true solar time correction FIRST, then the four pillars with hidden stems and Na Yin, plus luck cycles. Runs on the production Auspi

What data it sees

Do you need an account

No: the server works without sign-in

True solar time correction and solar-corrected BaZi / Four Pillars casting — historical DST, longitude and equation of time, with hour-branch boundary detection. The step most chart tools skip. Deterministic, no auth, no state.

Server tool list (3)

Raw names from tools/list. Only developers need these.

true_solar_timeConvert a recorded birth time (wall clock + IANA time zone + longitude) into true solar time — the time a BaZi / Four Pillars chart should actually be cast from. Returns the corrected instant, the total correction decomposed into DST + longitude + equation-of-time (the three always sum exactly), the resulting two-hour branch, distance to the nearest branch boundary, and whether the reported clock time even existed (spring-forward DST gaps, e.g. China 1986–91). Deterministic.
hour_branchWhich two-hour branch (子丑寅卯…) a given time falls in, and minutes to the nearest branch boundary. Use on an already-corrected time; for raw birth records use true_solar_time.
cast_pillarsCast a BaZi / Four Pillars chart the right way round: true solar time correction FIRST, then the four pillars with hidden stems and Na Yin, plus luck cycles. Runs on the production Auspice Oracle engine — same conventions as auspiceoracle.com/en/method (late Zi keeps the civil day; year/month turn at exact solar-term instants). Facts only: no strength verdicts, no favorable elements, no interpretation. Deterministic.