Vietnamese lunisolar calendar, 1900 to 2100

Conventions taken

The whole table is generated by the engine, not copied from any almanac. The lunar date follows UTC+7, the Vietnamese convention; the same solar day can fall on a different lunar day under the UTC+8 Chinese convention, and that difference is real around new moon. The day stem-branch counts continuously from the Julian day number, so it does not depend on the time zone. The solar term is the one in force at 12:00 noon Vietnam time on that day: on a day whose term begins after noon, that day's tiet_khi column still shows the previous term. To see which days a term begins on and at what time, read the tiet_khi_giao_trong_ngay and gio_giao_tiet columns, taken from the same engine as the moc-tiet-khi-1900-2100 dataset (error up to 14 minutes, see that dataset). The lunar mansion column uses the anchor of 21 September 2026 being the mansion Tam, taken from an almanac. That anchor checks itself: the twenty-eight mansion cycle is locked to the seven-day week because 28 divides by 7, each mansion belongs to one of the seven luminaries and each luminary to a fixed weekday, so an anchor off by one day shifts the whole luminary table. Verified across eleven years with no drift. The auspicious or inauspicious rating and the animal of each mansion are deliberately NOT included: sources disagree widely on both, and a mis-copied rating is something a reader takes away to choose a wedding date.