Jokyoreki (Jokyo Calendar) (貞享暦)
The Jokyoreki (Jokyo calendar) is a Japanese lunar-solar calendar, formerly used in Japan. It was the first native calendar compiled by Japanese.
Japanese calendar dates are in old lunar calendar style. The Christian Era and dates are in the Gregorian calendar style.
Duration of use
The Jokyoreki replaced the Senmyoreki (Senmyo calendar) on February 4, 1685, and was used for 70 years until February 10, 1755.
Jokyoreki was reformed to the Horyakureki (Horyaku calendar) on February 11, 1755.
Jokyoreki was completed by Harumi SHIBUKAWA, and then the adoption of that calendar was decided on December 5, 1684.
Completing a calendar of Japanese origin, Harumi SHIBUKAWA named his calendar the Yamatoreki (Yamato calendar), with taking into account the difference of longitude between China and Japan after making his own astronomical observations based on the Jujireki (Juji calendar) in China. Because the Senmyoreki at that time had been used for as long as 800 years, it accumulated errors; two days ahead at the actual lunar and solar movement. Additionally, private calendars based on the Senmyoreki were independently published in various parts of the country and some of these calendars indicated different dates; in result, Japan needed to unify these prevalent calendars all over the country and to make a calendrical reform. Planning to reform the Senmyoreki to the Daitoreki (Daito calendar) then used in Ming dynasty, Imperial Court issued the Sho (imperial decree) on April 17, 1684, that the existing calendar would be changed to the Daitoreki, but the Yamatoreki which Harumi SHIBUKAWA proposed the adoption of was officially accepted and named the calendar 'Jokyoreki' after the gengo (era name) of this era, Jokyo. Because of this achievement, Harumi SHIBUKAWA was assigned as newly created Tenmongata (official astronomer to the shogun) from the bakufu (Japanese feudal government headed by a shogun).
Incidentally, the reform of the calendar for the first time in 800 years gained topicality at that time; thus, Saikaku IHARA wrote "Koyomi (Ukiyozoshi), Calendar (Literally, Books of Floating World)," and Monzaemon CHIKAMATSU wrote "Kenjo no tenarai narabini shingoyomi (Wise Woman's Penmanship and the New Calendar)."