An astronomical catalog is a systematic collection of astronomical objects, such as stars, galaxies, and nebulae, organized for easy reference and study. These catalogs provide essential information, including the position, brightness, and other characteristics of celestial bodies. They serve as valuable resources for astronomers and researchers in understanding the universe. Some well-known examples of astronomical catalogs include the Messier Catalog, which lists prominent deep-sky objects, and the Hipparcos Catalog, which contains precise measurements of star positions and distances. These catalogs help scientists track changes in the night sky and facilitate the discovery of new celestial phenomena.