Astronomical Catalogs & Professional Sky Databases

Two catalogues compiled by George Abell. The 1958 catalogue of rich clusters of galaxies — later extended southward — became the standard reference for galaxy clusters, listing thousands of the densest concentrations in the Universe. Separately, Abell catalogued 86 large, faint planetary nebulae. Objects carry an 'Abell' number in both.

The first systematic catalogue of dark nebulae, compiled by Edward Emerson Barnard from his pioneering photographs of the Milky Way. The 1919 list of 182 objects was later extended to 370; each 'B' object is a cloud of interstellar dust silhouetted against the star fields behind it, such as B33, the Horsehead Nebula.

The great pre-photographic survey of the northern sky, carried out under Friedrich Argelander at Bonn and published from 1863. It recorded positions and magnitudes for about 325,000 stars to roughly ninth magnitude — the most comprehensive star catalogue of its era — and its 'BD' designations remain in use for naked-eye and telescopic stars today.

A list of 109 bright deep-sky objects compiled by the British amateur astronomer Sir Patrick Moore to complement the Messier Catalogue, which it deliberately avoids duplicating. Ordered by declination and spanning both hemispheres, it gathers showpiece galaxies, clusters, and nebulae — such as the Hyades and NGC 869/884 — that Messier omitted. Objects carry a 'C' number.

The authoritative catalogue of variable stars, first published in Moscow in 1948 and maintained since at the Sternberg Astronomical Institute. It assigns official variable-star designations and records variability type, period, and amplitude for tens of thousands of stars, serving as the reference for the naming of newly confirmed variables.

The standard catalogue of stars in the immediate solar neighbourhood, begun by Wilhelm Gliese and later extended with Hartmut Jahreiß. It lists the stars known to lie within about 25 parsecs of the Sun, with distances and motions; its 'GJ' (or older 'Gl') numbers are the usual designations for nearby red dwarfs and other close stars.

A catalogue of stars with large proper motions — at least half an arcsecond per year — compiled by Willem Luyten from decades of photographic plate comparisons. Because high proper motion usually signals a nearby star, the 'LHS' catalogue is a rich hunting ground for the Sun's closest neighbours, including many faint red and white dwarfs.

A comprehensive catalogue of galaxies begun by Paturel and collaborators, providing a unique 'PGC' identifier, position, and basic parameters for tens of thousands of galaxies. It forms the backbone of the HyperLEDA database, and its PGC numbers are widely used as a standard cross-reference for galaxies lacking a common name.

A catalogue of 258,997 stars compiled by the Smithsonian Astrophysical Observatory, combining earlier positional catalogues to support satellite tracking. Its dense, uniform coverage and widely printed star atlas made 'SAO' numbers a long-standing standard designation for stars down to about ninth magnitude.

A catalogue of HII regions — clouds of ionised hydrogen glowing around hot young stars — compiled by Stewart Sharpless. Its second edition (Sh2, 1959) lists 313 emission nebulae across the northern Milky Way, including many of the sky's great star-forming complexes. Objects carry an 'Sh2' number.

An astrometric and photometric catalogue of about 2.5 million of the brightest stars, derived from the star-mapper data of ESA's Hipparcos satellite. Named in honour of Tycho Brahe, it provides positions, proper motions, and two-colour photometry, and its 'TYC' identifiers are a standard reference for stars fainter than the main Hipparcos catalogue.

A catalogue of 12,921 galaxies north of declination −02°30′, compiled by Peter Nilson at Uppsala from the Palomar Sky Survey. Selected mainly by apparent size, it was for decades the most complete catalogue of nearby northern galaxies and remains a common cross-reference; objects carry a 'UGC' number.

The principal database of double and multiple stars, maintained by the United States Naval Observatory. It gathers positions, separations, position angles, and magnitudes for well over a hundred thousand pairs from centuries of measurements, and its 'WDS' identifiers are the standard reference for binary and multiple systems.

An early catalogue of high-proper-motion stars assembled by Max Wolf, a pioneer of astrophotography, from his survey of moving stars. Its 'Wolf' numbers survive as designations for several well-known nearby stars — most famously Wolf 359, one of the closest stars to the Sun.

The positional catalogues that pin down where the stars are — from Argelander's pre-photographic Bonner Durchmusterung and the Smithsonian's SAO catalogue to the space-based precision of Hipparcos, Tycho-2, and Gaia.

The catalogues of bright deep-sky showpieces made for the eye and the small telescope — Charles Messier's eighteenth-century list of 'objects to avoid' when comet-hunting, and Patrick Moore's later Caldwell Catalogue that gathers the bright objects Messier passed over.

The New General Catalogue and its two Index Catalogue supplements, compiled by J. L. E. Dreyer from the visual discoveries of the Herschels and their successors. Together the NGC and IC number nearly 13,000 galaxies, clusters, and nebulae and remain the most widely used designations for deep-sky objects.

The great reference catalogues of galaxies — the Uppsala General Catalogue's size-selected northern galaxies and the Principal Galaxies Catalogue that underpins the HyperLEDA database, providing standard identifiers for galaxies far beyond those with common names.

The catalogues that map the Sun's immediate neighbourhood — Gliese's census of stars within about 25 parsecs, and the high-proper-motion catalogues of Luyten (LHS) and Max Wolf, whose fast-moving stars are usually the closest ones.

The specialist catalogues of interstellar clouds — Sharpless's HII regions glowing around young stars, Barnard's dark dust clouds silhouetted against the Milky Way, and Abell's large, faint planetary nebulae. Together they map the gas and dust between the stars.

The catalogues of stars that change and stars that come in pairs — the General Catalogue of Variable Stars, which names and classifies variables, and the Washington Double Star Catalog, the master reference for binary and multiple systems.

The system introduced by Johann Bayer in his 1603 atlas Uranometria, labelling the bright stars of each constellation with a Greek letter followed by the Latin genitive of the constellation's name — so α Orionis is Betelgeuse, even though Rigel (β Orionis) is usually the brighter of the two, a reminder that the ordering is only approximate. Roughly in order of brightness, Bayer letters remain the most familiar designations for naked-eye stars.

A numbering scheme drawn from John Flamsteed's star catalogue, published posthumously in 1725, that labels the stars of each constellation with a number in order of increasing right ascension — so 61 Cygni is the sixty-first Flamsteed star of Cygnus. Flamsteed numbers name many stars that have no Bayer letter.

The scheme for naming variable stars, formalised in the General Catalogue of Variable Stars. Within each constellation the first variables take the letters R through Z, then two-letter combinations RR through ZZ and AA through QZ, and thereafter V335, V336, and so on — a system that grew from a handful of early discoveries into a labelling scheme for tens of thousands of variables.