Xiao'an xinfa 曉庵新法

Xiao'an xinfa 曉庵新法 is a book on astronomical calculations written during the early Qing period 清 (1644-1911) by Wang Xichan 王錫闡 (1628-1682), courtesy name Yinxu 寅旭, style Yubu 余不, Xiao'an 曉庵 (also written 曉菴) or Tiantongyi Sheng 天同一生, from Wujiang 吳江, Jiangsu.

Unwilling to serve the Qing dynasty, he chose to live in seclusion, dedicating himself to reading and working as a private tutor. He specialized in astronomy and frequently conducted astronomical observations. He authored an explanation of the movements of the five planets, Wuxing xingdu jie 五星行度解. His collected writings are called Xiao'an Xiansheng wenji 曉庵先生文集.

The first of the book's 6 juan explains methods related to geometry and circular functions, while the remaining five fascicles discuss techniques for predicting solar and lunar eclipses, as well as the transits of the five planets. The book pioneered a method for calculating the azimuth angles of the beginning and end of solar and lunar eclipses (ri-yueshi chukui, fuyuan fangwei jiao 日月食初虧、復圓方位角), significantly improving the accuracy of eclipse predictions.

Additionally, he independently invented a method for calculating the transits (lengri 凌日) of Venus and Mercury and explored the reason behind planetary orbits around the Sun, attributing it to the Sun's gravitational pull, which he compared to the attraction of a magnet to a needle.

The book is included in the series Shoushange congshu 守山閣本叢書, Cuilangganguan congshu 翠瑯軒叢書, Muxixuan congshu 木犀軒叢書, Siku quanshu 四庫全書 and Congshu jicheng chubian 叢書集成初編.