Astronomy Hacks

Identify Stars by Catalog Designations

Learn about the stellar catalogs used by amateur astronomers.

Of the thousands of stars visible to the naked eye—and millionsvisible with optical aid—only a few hundred of the brightest have proper or common names, such as Vega or Sirius. Although proper names are convenient for referring to bright “guidepost” stars, astronomers also need unambiguous designations for dimmer stars.

It is possible, although awkward, to specify a particular star by giving its coordinates [Hack #17]. For example, we could say, the star located at 14h15m40.35s right ascension and +19°11’14.2” declination, but that gets old fast. As a more convenient alternative, astronomers have developed star catalogs, which assign each star a unique short identifier, such as α-Boötis or HIP 69673. (All three of these designations specify Arcturus, the brightest star in the constellation Boötes.)

Early astronomers began the work of cataloging the stars visible to the naked eye, dividing the stars by constellation and then assigning unique identifiers to each. Modernday astronomers have continued that practice, but they now treat the sky as a contiguous whole and catalog stars without respect to constellation. Surprisingly, the star naming syntax of some catalogs produced 300 to 400 years ago remains in common use. Here are the stellar catalogs you need to be familiar with.

The Bayer Catalog

The German astronomer Johann Bayer (1572–1625) published Uranometria, the first comprehensive ...