[1] It was published in the Tenpō era (1830–1844) it remained in use throughout the late Edo period, from 1844 to 1872.
Marking the final traditional calendar system devised by Japanese astronomers and mathematicians.
[2] The Tenpō calendar is a lunisolar system which adopted Teiki-hō method, dividing solar terms by solar longitude instead of time, unlike the previous Heiki-hō method.
Observations from Kyoto[3][4] dictates the time used for determining solar terms and lunar phases.
In 2033, for the first time in the calendar's history, there will be only one complete lunar month between the autumnal equinox and winter solstice, and two chūki-less months between the winter solstice and 2034 spring equinox.