Methodology

Local civil time is converted to UTC with the IANA time-zone database (historical offsets and daylight-saving rules) via Luxon. Places are found with Open-Meteo geocoding, which also supplies the zone; coordinates and zone can be entered manually. Non-existent (spring-forward) and ambiguous (fall-back) local times are flagged.

New moons, Sun longitude and illumination come from astronomy-engine (VSOP87 / lunar theory, ~1 arc-minute accuracy). New moon instants are checked in tests against the NASA/Espenak phase tables to within 3 minutes.

1-based ordinal of the most recent astronomical new moon among all new moons whose local civil date (birth time zone) falls in the Gregorian birth year. If birth precedes the year's first new moon, LM is reported as unresolved.

floor(days elapsed since the most recent new moon) + 1, using exact instants (no rounding before the floor). Digital root = 1 + ((LD − 1) mod 9).

Solar year begins at the exact instant of Li Chun (Sun apparent geocentric longitude 315°, ≈ Feb 4), compared in UTC — not 1 January or Chinese New Year. r = digital root of the year's last two digits. Before 2000: male 10 − r, female 5 + r; from 2000: male 9 − r, female 6 + r; reduced to 1–9. The original number is always shown. For Eight Mansions directions only, 5 is substituted: male → 2, female → 8 (schools differ).

Year boundary is the same exact Li Chun instant as Gua. Year star = 11 − digit sum of the solar year, reduced to 1–9. Solar months begin at the 12 jié solar terms (Sun 315°, 345°, 15°, …). The Tiger-month star is 8, 2 or 5 for year stars {1,4,7}, {2,5,8}, {3,6,9}, decreasing by one each month. Tendency: fly the month star from the centre; the Lo Shu number of the palace holding the year star. When year and month stars coincide the tendency is left unresolved.

Each of the four layers flies independently along C → NW → W → NE → S → N → SW → E → SE, adding one per palace and wrapping 9 → 1. South is displayed at the top. The Gua palace is the palace whose standard Lo Shu number equals the original Gua.

The traditional annual centre is 3 for feng shui year 2024, decreasing by one each year with 1 → 9 wrap; equivalently reduce 2027 − year to 1–9. Fly this centre forward using the existing palace path and read the home-facing palace. North for 2024–2032 is 8, 7, 6, 5, 4, 3, 2, 1, 9. Reference Calendar Year deliberately selects that feng shui year irrespective of today. Reference Date uses a separate civil date, time and IANA zone, resolving the active year against the exact Li Chun instant. January 6, 2025 is in solar year 2024 (North 8), while explicitly selecting year 2025 gives North 7. Ambiguous or nonexistent reference times stay unresolved. Supported reference years: 1900–2099. No facing direction is assumed.

D (top-left) = Traditional Daily Flying Star (traditional convention, see below); the former H1 dr(LD) is rejected (fails July 1, 1983). H3: bottom-left centre = 12 − LM, defined only for LM 3–11 (LM 1, 2, 12, 13 → Not determined; no wrapping). H4: bottom-right centre = Nine Star Ki year star. All agree with the three locked charts but are undocumented hypotheses, isolated in their own module. H2: P (centre layer) = the annual Flying Star in the home-facing palace for the selected reference period. This personal chart assignment is experimental, even though the underlying annual star is a traditional convention. Missing reference parameters leave P unresolved. Historical matches are not independent validation. Any centre can be overridden; 'Reset to calculated' removes all overrides, and editing birth details clears them so no previous person's centres carry over.