List of Constellations by Accuracy of Bayer Designations

The brighter stars of constellations are designated by Greek letters according to Bayer Designations, for which the original intent was for the brightest star of a constellation to be designated Alpha (α), the second brightest Beta (β), the third brightest Gamma (γ), and so on through the Greek alphabet. Astronomers, including Bayer, however, hardly made an effort to make Bayer Designations actually indicate the brightest rank of stars in constellations, sometimes because it is hard to differentiate brightnesses (Bayer designated the stars with Greek letters before sufficient modern quantitative technology), sometimes because they wanted to have Greek letters outline patterns, and sometimes when it seems that they could only have been fooling around. In any case, here is a list of constellations ordered from most accurately Bayer-designated to most badly Bayer-designated. The quantity first stated is the sum of the positive differences between the apparent magnitude of the star actually Bayer-designated a Greek letter and the apparent magnitude of the star that should have been respectively Bayer-designated that letter. Divided by the number of Bayer-designated stars in the constellation, the final quantity shows the average amount by which a Bayer designation in that constellation is off by magnitude.

Here’s a picture of Orion with eight labeled stars, with magnitudes attached, for reference.

orionmagnitudes

Note that with less stars Bayer-designated, it is naturally harder to make gigantic errors, and thus those most impressively Bayer-designated are those with many stars accurately Bayer-designated.

Canes Venatici: 0/2=0
Leo Minor: 0/1=0
Lynx: 0/1=0
Vulpecula: 0/1=0

Sextans: 0.02/5<0.01

Coma Berenices: 0.18/3=0.06
Scutum: 0.44/7=0.06

Dorado: 1.47/12=0.12
Vela: 0.92/7=0.13
Sculptor: 2.22/16=0.14
Lacerta: 0.28/2=0.14
Triangulum Australe: 1.44/10=0.14

Corona Australis: 1.77/11=0.16
Apus: 1.66/10=0.17
Volans: 1.66/10=0.17
Centaurus: 4.07/23=0.18
Monoceros: 1.09/6=0.18
Circinus: 1.49/8=0.19
Columba: 2.91/15=0.19
Mensa: 2.91/15=0.19
Cassiopeia: 4.79/24=0.20

Lyra: 2.73/13=0.21
Perseus: 4.65/22=0.21
Canis Minor: 1.52/7=0.22
Corona Borealis: 4.51/20=0.23
Delphinus: 2.26/10=0.23
Chamaeleon: 2.94/13=0.23
Caelum: 1.72/7=0.25
Camelopardalis: 0.74/3=0.25
Crux: 2.98/12=0.25

Grus: 5.25/21=0.25
Pictor: 3.05/12=0.25
Hydrus: 4.20/16=0.26
Reticulum: 2.69/10=0.27
Virgo: 6.69/24=0.28
Lupus: 6.83/24=0.28
Equuleus: 2.03/7=0.29
Triangulum: 1.75/6=0.29
Pyxis: 2.92/10=0.29

Horologium: 3.00/10=0.30
Gemini: 7.01/23=0.30
Andromena: 7.57/24=0.32
Cepheus: 5.70/18=0.32
Phoenix: 7.30/23=0.32
Indus: 5.07/15=0.34
Telescopium: 4.09/12=0.34
Cancer: 7.90/23=0.34
Lepus: 4.47/13=0.34
Pegasus: 7.65/22=0.35
Hercules: 8.01/23=0.35

Leo: 8.43/24=0.35
Ursa Minor: 3.53/10=0.35
Aries: 6.79/19=0.36
Serpens: 8.64/24=0.36
Crater: 4.34/12=0.36
Ara: 5.48/15=0.37
Musca: 4.04/11=0.37
Fornax: 7.5/20=0.38
Norma: 3.87/10=0.39
Boötes: 9.41/24=0.39
Aquarius: 9.42/24=0.39
Pavo: 8.75/22=0.40
Draco: 9.56/24=0.40

Ophiuchus: 9.22/23=0.40
Auriga: 9.24/23=0.40
Cygnus: 9.79/24=0.41
Pisces: 10.07/24=0.42
Tucana: 6.34/15=0.42
Hydra: 10.37/24=0.43
Microscopium: 4.47/10=0.45

Carina: 3.60/8=0.45
Octans: 10.80/24=0.45
Aquila: 10.37/23=0.45
Eridanus: 10.38/23=0.45
Capricornus: 10.92/24=0.46
Taurus: 10.98/24=0.46
Cetus: 10.22/22=0.46
Orion: 11.56/24=0.48

Ursa Major: 12.25/24=0.51
Piscis Austrinus: 7.34/14=0.52
Antlia: 3.73/7=0.53

Canis Major: 11.64/21=0.55
Puppis: 5.13/9=0.57

Sagitta: 5.13/8=0.64

Corvus: 4.62/7=0.66

Libra: 14.57/18=0.81
Sagittarius: 19.76/24=0.82

Scorpius: 20.12/22=0.91

Brightest stars in Libra: β (2.61), α (2.75), σ (3.25), υ (3.60), τ (3.66), γ (3.91), θ (4.13)
Brightest stars in Sagittarius: ε (1.79), σ (2.05), ζ (2.60), δ (2.72), λ (2.82), π (2.88), γ (2.98), η (3.10), φ (3.17), τ (3.32)
Brightest stars in Scorpius: α (1.06), λ (1.62), θ (1.86), δ (2.29), ε (2.29), κ (2.36), β (2.56), υ (2.70), τ (2.82), π (2.89), σ (2.90), ι (2.99)

In Scorpius, it can be seen that in α through λ, what is being designated is the backbone of the scorpion, traced from the heart upwards and then downwards. In Sagittarius, whatever pattern is being used is thoroughly mysterious, and α (3.96) literally comes 16th in the Greek letters. In these exceptional cases, Bayer Designations may show important patterns, but whatever they are, brightness is completely out of the question.

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