Chongzhen calendar

It was developed by the lead of Xu Guangqi with the assistance of the Jesuit scholars Johann Schreck and Johann Adam Schall von Bell[2] from 1624 to 1644, and was dedicated to the Chongzhen Emperor.

This calendar is notable for systematically introducing the concepts and development of European mathematics and astronomy to China for the first time, and constituted the first major collaboration between scientists from Europe and from the Far East.

[2] Documented in more than 100 volumes of books, It offered an encyclopedic account of Euclidean geometry, spherical geometry and trigonometry, with extensive translations and references to Euclid's Elements and the works of Nicolaus Copernicus, Johannes Kepler, Galileo Galilei, and Tycho Brahe, whose Tychonic system was used its main theoretical basis.

[3][4] In addition, a comprehensive set of mathematical tables and astronomical ephemerides was included.

The main changes introduced by the calendar are: This calendar was used from the early Chinese Qing Dynasty into the early modern era, but was modified and replaced in 1914 and again in 1928,[1] with various minor modifications since then.