真太陽時 · True solar time
A birth certificate records a clock reading. The hour pillar is defined by the sun. Between those two sit three corrections most calculators skip — and each one can move a chart by a whole branch.
Zones move. Wars, occupations and reforms have rewritten them again and again, and a calculator that applies today's offset to a 1942 birth is reading the wrong clock. Computed from the historical record:
| Birthplace | Date | Offset then | Offset today |
|---|---|---|---|
| London | 15/6/1942 | UTC+2 | UTC+1 |
| Paris | 15/6/1944 | UTC+2 | UTC+2 (unchanged) |
| Madrid | 15/6/1938 | UTC+2 | UTC+2 (unchanged) |
| Shanghai | 15/6/1948 | UTC+9 | UTC+8 |
| New York | 15/6/1943 | UTC-4 | UTC-4 (unchanged) |
A London birth at 9:00 in June 1942 was recorded under UTC+2 — British Double Summer Time. Apply today's UTC+1 and the whole chart shifts an hour: 丁卯 becomes 戊辰, a different hour pillar entirely. Each note in the record has a story: London, British Double Summer Time, kept through the war years; Paris, German-occupied Paris ran on Berlin summer time; Madrid, before Spain's 1940 move to Central European Time; Shanghai, Republic-era daylight saving, gone since 1949; New York, “War Time”, year-round daylight saving 1942–45.
A timezone is a band a thousand kilometres wide sharing one clock; the sun crosses it for four minutes of solar time per degree of longitude. Paris sits at 2.35°E in a zone built on 15°E, so a Paris clock noon on 1 March is really 10:56 solar time — the longitude correction plus the equation of time, the seasonal wobble that runs the sun up to sixteen minutes off uniform time.
The BaZi year turns at Li Chun, in early February, computed from the sun's position. A January birth belongs to the previous year's pillar — every year's true boundary is here.
Mystic Ragondin applies all three corrections and shows you what it applied, in plain sight under your pillars. It runs in your browser, and nothing about you leaves your device — compute your chart.