Astronomers must be able to refer to a given star or other celestial object after studying it. This can be done with the star coordinates or with a name. Our knowledge of the existence of the fainter stars in the optical sky derives from surveys of the sky, such as a series of large-area photographs or the counting rate data from an x-ray detector that scans the entire sky. Such surveys typically yield the celestial coordinate of each located object. Interesting objects of a given type that are found in such surveys can be plotted on maps of the sky (charts) or listed with positions and other information in printed catalogs.
Was this article helpful?