SAJU, GYEOL · LIBRARY
Birthplace, local time and births abroad
Enter the time shown by the local clock at birth. Do not convert it to Korean time or subtract daylight saving yourself.
The place is part of the calculation
Select a country or territory, then choose a city suggestion including its state or province. A shared city name is not enough to guess the location. English names are searchable, and some overseas places also have Korean aliases.
South Korea uses representative city, county and district longitudes. Overseas places use GeoNames populated-place coordinates and IANA time zones. This is not a street-address geocoder or a complete directory of every village. Substituting a nearby city can change longitude or even the time zone, which matters especially near a calculation boundary.
Use the clock time recorded at the birthplace
A New York birth should use the recorded New York clock time, not a conversion to Seoul time. Historical standard time and daylight saving are applied for the selected location. Manually converting the time first can change the birth instant incorrectly.
New York on 2024-07-01 is on daylight saving time. An input of 00:20 receives a local mean solar-time correction of about −56 minutes, giving 2024-06-30 23:24. This worked example shows why correcting the time can also change the day used in the chart.
When a clock skips or repeats an hour
When a clock jumps from 02:00 to 03:00, 02:30 in the skipped interval never occurs. New York 2024-03-10 02:30 is rejected for this reason, with a request to check the original record.
When clocks move backward, a time may occur twice. We use the earlier occurrence and show a note. New York 2024-11-03 01:30 is one example. A clock time alone cannot establish which occurrence was intended; consult the original record if the distinction matters.
Solar-time correction and solar terms
The correction is longitude × 4 minus the historical UTC offset expressed in minutes. Seoul at 126.978° E and UTC+9 gives about −32 minutes; the registered representative point for Tokyo gives about +19 minutes. We do not apply the equation of time, round to minutes, and keep the correction within ±12 hours near the international date line.
Day and hour pillars use the corrected local date and time. Year and month pillars compare solar terms at the actual birth instant expressed in China Standard Time for the calendar engine. With an unknown time, local noon is assumed and the hour pillar and solar-time correction are omitted. On a solar-term date, that noon assumption can affect the year or month pillar.
Sources and references
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