What I checked: The flying stars in the Nine Palaces of Luoshu entered the middle palace one after another according to the flow of time.
Any star that enters the middle palace is called the star of the season. The so-called on-duty means that the order is given at that time, just like taking turns to be on duty. At a certain time, a certain star will be on duty, so the on-duty star is also called the on-duty star. If a certain star is on duty, this star is a prosperous star.