正元历
Tang · Xu Chengsi, Yang Jingfeng
Overview
Promulgated in 785 CE under Xu Chengsi and Yang Jingfeng, used in the middle Tang.
Key data
| Item | Detail |
|---|---|
| Period of use | 785 – 821 CE |
| Compilers | Xu Chengsi, Yang Jingfeng |
| Year head | Jian-yin |
Development
The Zhengyuan calendar was made by Xu Chengsi and Yang Jingfeng, promulgated in 785 CE and used until 821.
It too worked within the old methods, taking the Dayan as its basis and adjusting it against observation.
The office of the calendrist
The Tang kept an Astronomical Bureau (Taishiju, later Sitian Tai) for the calendar, staffed by specialists. A calendar had to be measured, debated and promulgated — the work of many, not one.
Compiled and arranged by Chujia Kuang.