Introduction of the Methods for Determining the Zero Point of A Catalog

In this article the definitions of the zero point corrections of a catalog are summed up and the methods for determining the equinox and equator corrections by means of the observations of the Sun, the Moon and planets are introduced. It is pointed out that in order to improve the accuracy of the determination of the zero point corrections of a catalog, there should be some ideal objects to be observed and higher accurate observations distributed along their orbits as homogeneously as possible.