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Genitives

The form of the Latin name of a constellation used when describing objects, especially stars, within that constellation. For example, the genitive form of 'Centaurus' is 'Centauri'; hence the famous 'Alpha Centauri', the brightest star in that constellation.


Strictly genitive refers to the grammatical case used to denote possession or association. In English this is commonly denoted by the word 'of', but in Latin the case is indicated by inflection; that is, a change to the ending of the word in question. This rule holds for the Latin names given to the constellations, so, following the example above, 'Alpha Centauri' literally means 'Alpha (the brightest star) of Centaurus'.

The most familiar use of genitive constellation names is in Bayer desginations, which use Greek letters to rank the stars of a constellation - at least theoretically - by magnitude, followed by the genitive case of the constellation's name. 'Alpha Centauri' is a famous example of this system, as are names like 'Epsilon Eridani' (the Epsilon star of Eridanus, the River) or 'Tau Ceti' (the Tau star of Cetus, the Whale).

Genitive constellation names are also used by the Flamsteed system, which uses numbers instead of Greek letters, counting west to east across the constellation. For example, the brilliant star Sirius is designated 'Alpha Canis Majoris' on the Bayer system, and also '9 Canis Majoris' by the Flamsteed numbers (that is, the ninth Flamsteed star from the western boundary of Canis Major). Genitives are also used in variable designations (such as 'UV Ceti') and very occasionally in the proper names of stars such as Proxima Centauri or Mira Ceti.

Each constellation has an official abbreviation of its name, and it is common to see this used in place of the full genitive form. For example, the first extrasolar planet to be discovered orbits a star designated in full '51 Pegasi' (that is, fifty-first of the eighty-nine Flamsteed stars in the constellation Pegasus). In practice, this star is almost universally referred to as simply '51 Peg'.

The table below lists the genitive forms and abbreviations for all eighty-eight officially recognised constellations. There are two cases (Camelopardalis and Puppis) where the genitive form remains the same as the constellation name; in all other cases the ending of the name changes to form the genitive.

ConstellationGenitiveAbbreviation

Andromeda Andromedae And
Antlia Antliae Ant
Apus Apodis Aps
Aquarius Aquarii Aqr
Aquila Aquilae Aql
Ara Arae Ara
Aries Arietis Ari
Auriga Aurigae Aur

Boötes Boötis Boo

Caelum Caeli Cae
Camelopardalis Camelopardalis Cam
Cancer Cancri Cnc
Canes Venatici Canum Venaticorum CVn
Canis Major Canis Majoris CMa
Canis Minor Canis Minoris CMi
Capricornus Capricorni Cap
Carina Carinae Car
Cassiopeia Cassiopeiae Cas
Centaurus Centauri Cen
Cepheus Cephei Cep
Cetus Ceti Cet
Chamæleon Chamæleonis Cha
Circinus Circini Cir
Columba Columbae Col
Coma Berenices Comae Berenicis Com
Corona Australis Coronae Australis CrA
Corona Borealis Coronae Borealis CrB
Corvus Corvi Crv
Crater Crateris Crt
Crux Crucis Cru
Cygnus Cygni Cyg

Delphinus Delphini Del
Dorado Doradis Dor
Draco Draconis Dra

Equuleus Equulei Equ
Eridanus Eridani Eri

Fornax Fornacis For

Gemini Geminorum Gem
Grus Gruis Gru

Hercules Herculis Her
Horologium Horologii Hor
Hydra Hydrae Hya
Hydrus Hydri Hyi

Indus Indi Ind

Lacerta Lacertae Lac
Leo Leonis Leo
Leo Minor Leonis Minoris LMi
Lepus Leporis Lep
Libra Librae Lib
Lupus Lupi Lup
Lynx Lyncis Lyn
Lyra Lyrae Lyr

Mensa Mensae Men
Microscopium Microscopii Mic
Monoceros Monocerotis Mon
Musca Muscae Mus

Norma Normae Nor

Octans Octantis Oct
Ophiuchus Ophiuchi Oph
Orion Orionis Ori

Pavo Pavonis Pav
Pegasus Pegasi Peg
Perseus Persei Per
Phoenix Phoenicis Phe
Pictor Pictoris Pic
Pisces Piscium Psc
Piscis Austrinus* Piscis Austrini PsA
Puppis Puppis Pup
Pyxis Pyxidis Pyx

Reticulum Reticuli Ret

Sagitta Sagittae Sge
Sagittarius Sagittarii Sgr
Scorpius Scorpii Sco
Sculptor Sculptoris Scl
Scutum Scuti Sct
Serpens Serpentis Ser
Sextans Sextantis Sex

Taurus Tauri Tau
Telescopium Telescopii Tel
Triangulum Trianguli Tri
Triangulum Australe Trianguli Australis TrA
Tucana Tucanae Tuc

Ursa Major Ursae Majoris UMa
Ursa Minor Ursae Minoris UMi

Vela Velorum Vel
Virgo Virginis Vir
Volans Volantis Vol
Vulpecula Vulpeculae Vul

* Piscis Austrinus, the constellation of the Southern Fish, is sometimes called Piscis Australis; in that case its genitive form is also Piscis Australis (the abbreviation remains 'PsA' in either case).

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