What was the name of the official who specialized in calendar in ancient China?

Different dynasties have different titles. Generally speaking, officials who study these are knowledgeable people with a wide range of work, and they should study astronomical calendars, history, and the magic numbers of Yin and Yang.

For example, in the Spring and Autumn Period, Lao Zi was called Taishiling, which was equivalent to the curator of the National Library. In the Tang Dynasty, Li's official name was Si.