After Wang Mang deposed the Han Dynasty and instituted his new Xin Dynasty, he needed to promulgate a new calendar to mark the occasion. One of his court astronomers, Liu Xin, developed a new calendar that integrated the lunar and solar cycles with the planetary cycles and imbued it with numerological significance. We then talk about how Huan Tan, another astronomer of the era, would have gone about measuring the lunar mansions.
