NINEHOUND / CALENDAR & CULTURE TOOLS
Turn a UTC clock reading into an astronomical Julian Day number.
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WORKED EXAMPLE
Gregorian date：2000-01-01 · Clock time：12:00
2000-01-01 12:00 UTC · Input precision: one minute
Enter a Gregorian UTC date and time. Julian Day integers turn over at noon. January 1, 2000 at 12:00 UTC is JD 2451545.0.
Output is rounded to six decimal places, but input precision is one minute. This is a UTC-based mapping, not TT/TDB, leap-second modelling or a Julian-calendar conversion.
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