Lists and catalogs of galaxies

Classification and common categories

Galaxies are often grouped by morphology, environment and observational properties. Typical categories used in lists include:

• Morphological types: spiral, elliptical, lenticular (S0) and irregular — originally organized under Hubble's tuning-fork scheme and modern refinements.
• Activity: active galactic nuclei (AGN), quasars, starburst galaxies and radio galaxies, identified by energetic processes at their centers or intense star formation.
• Distance or brightness: nearest galaxies, brightest in the sky, or highest-redshift (most distant) examples.
• Environmental grouping: members of the Local Group or the Virgo Cluster, satellite galaxies around a larger host, and systems inside galaxy clusters or filaments.

Major catalogs and curated lists

Astronomical catalogs collect galaxies by systematic surveys or historical observations. Well-known compilations include historical catalogs (Messier and the New General Catalogue) and large survey catalogs produced by photographic and digital sky surveys. The first widely used modern compilation was the Catalogue of Galaxies and of Clusters of Galaxies; later efforts and digital surveys expanded the number and level of detail for listed objects.

Examples of commonly referenced lists and catalogs are provided as curated resources: lists of individual galaxies, compilations of galaxy clusters, and broad survey results and context summaries accessible via general resources such as comprehensive astronomical summaries.

Notable examples and groups

Some galaxies appear frequently in lists because they are nearby, bright, or scientifically important. The Andromeda Galaxy and the Milky Way are often cited as representative large spirals; the Large and Small Magellanic Clouds are well-known irregular satellites of the Milky Way. Other frequently listed systems include iconic objects like the Whirlpool and Sombrero galaxies, and extreme sources such as luminous quasars or galaxies undergoing dramatic mergers. Lists also highlight galaxy groups and clusters, which serve as laboratories for studying galaxy evolution and large-scale structure.

Uses and importance of galaxy lists

Organized lists are essential tools in observational astronomy and cosmology. They allow researchers to select targets for follow-up observations, to compile statistical samples for population studies, and to cross-match objects across different wavelength surveys. Educators and amateur astronomers also rely on compact lists (for example, visible targets for small telescopes) when planning observations.

Distinctions and notable facts

It is important to distinguish between a galaxy and a galaxy cluster: a galaxy is a single gravitationally bound system of stars, gas and dark matter, while a cluster contains many galaxies bound together and embedded in a hot intracluster medium. Catalogs vary in scope and criteria: some list every resolved source above a survey threshold, others emphasize specific physical properties. Because the sky has been observed at many wavelengths, complementary lists exist for infrared, radio, ultraviolet and X-ray selected galaxy samples.