Editing Bayer designation (section)

==Revised designations==
[[Ptolemy]] designated four stars as "border stars", each shared by two constellations: [[Alpheratz]] (in [[Andromeda (constellation)|Andromeda]] and [[Pegasus (constellation)|Pegasus]]), [[Elnath]] (in [[Taurus (constellation)|Taurus]] and [[Auriga (constellation)|Auriga]]), [[Nu Boötis]] ([[Nu1 Boötis|Nu<sup>1</sup>]] and [[Nu2 Boötis|Nu<sup>2</sup>]])(in [[Boötes]] and [[Hercules (constellation)|Hercules]]) and [[Fomalhaut]] (in [[Piscis Austrinus]] and [[Aquarius (constellation)|Aquarius]]).<ref name="LostStars"/>{{rp|p. 23}} Bayer assigned the first three of these stars a Greek letter from both constellations: {{nowrap|[[Alpha Andromedae]] {{=}} Delta Pegasi}}, {{nowrap|[[Beta Tauri]] {{=}} Gamma Aurigae}}, and {{nowrap|[[Nu Boötis]] {{=}} Psi Herculis}}. (He catalogued Fomalhaut only once, as [[Alpha Piscis Austrini]].) When the [[International Astronomical Union]] (IAU) assigned definite boundaries to the constellations in 1930, it declared that stars and other celestial objects can belong to only one constellation. Consequently, the redundant second designation in each pair above has dropped out of use.<ref name=iau2>{{cite book|author1=Eugène Delporte|author2=International Astronomical Union|title=Délimitation scientifique des constellations|url=https://books.google.com/books?id=v3XvAAAAMAAJ|year=1930|publisher=At the University press}}</ref>

Bayer assigned two stars duplicate names by mistake: {{nowrap|[[Xi Arietis]]}} (duplicated as {{nowrap|Psi Ceti}}) and {{nowrap|[[Kappa Ceti]]}} ([[Kappa1 Ceti|Kappa<sup>1</sup>]] and [[Kappa2 Ceti|Kappa<sup>2</sup>]]) (duplicated as {{nowrap|g Tauri}}). He corrected these in a later atlas, and the duplicate names were no longer used.<ref name="LostStars"/>{{rp|p. 23}}

Other cases of multiple Bayer designations arose when stars named by Bayer in one constellation were transferred by later astronomers to a different constellation. Bayer's Gamma and Omicron Scorpii, for example, were later reassigned from [[Scorpius]] to [[Libra (constellation)|Libra]] and given the new names [[Sigma Librae|Sigma]] and [[Upsilon Librae]].<ref name="LostStars"/>{{rp|p. 196}} (To add to the confusion, the star now known as [[Omicron Scorpii]] was not named by Bayer but was assigned the designation o Scorpii (Latin lowercase 'o') by Lacaille—which later astronomers misinterpreted as omicron once Bayer's omicron had been reassigned to Libra.)<ref name="LostStars"/>{{rp|p. 278}}

A few stars no longer lie (according to the modern constellation boundaries) within the constellation for which they are named. The [[proper motion]] of [[Rho Aquilae]], for example, carried it across the boundary into [[Delphinus]] in 1992.<ref name=moore>{{cite book|author=Patrick Moore|title=The Observer's Year: 366 Nights of the Universe|url=https://books.google.com/books?id=p87TBwAAQBAJ&pg=PA132|date=29 June 2013|publisher=Springer Science & Business Media|isbn=978-1-4471-3613-2|pages=132–}}</ref><ref name=hirshfeld>{{cite journal | display-authors=1 | last1=Hirshfeld | first1=A. | last2=Sinnott | first2=R. W. | last3=Ochsenbein | first3=F. | last4=Lemay | first4=D. | title=Book-Review - Sky Catalogue 2000.0 - V.1 - Stars to Magnitude 8.0 ED.2 | journal=Journal of the Royal Astronomical Society of Canada | volume=86 | issue=4 | page=221 |date=August 1992 | bibcode=1992JRASC..86..221L }}</ref>

A further complication is the use of numeric superscripts to distinguish neighboring stars that Bayer (or a later astronomer) labeled with a common letter. Usually these are [[double star]]s (mostly optical doubles rather than true [[binary star]]s), but there are some exceptions such as the chain of stars [[Pi1 Orionis|π<sup>1</sup>]], [[Pi2 Orionis|π<sup>2</sup>]], [[Pi3 Orionis|π<sup>3</sup>]], [[Pi4 Orionis|π<sup>4</sup>]], [[Pi5 Orionis|π<sup>5</sup>]] and [[Pi6 Orionis|π<sup>6</sup>]] [[Pi Orionis|Orionis]]. The most stars given the same Bayer designation but with an extra number attached to it is [[Psi Aurigae]]. ([[Psi1 Aurigae|ψ<sup>1</sup>]], [[Psi2 Aurigae|ψ<sup>2</sup>]], [[Psi3 Aurigae|ψ<sup>3</sup>]], [[Psi4 Aurigae|ψ<sup>4</sup>]], [[Psi5 Aurigae|ψ<sup>5</sup>]], [[Psi6 Aurigae|ψ<sup>6</sup>]], [[Psi7 Aurigae|ψ<sup>7</sup>]], [[Psi8 Aurigae|ψ<sup>8</sup>]], [[Psi9 Aurigae|ψ<sup>9</sup>]], [[16 Lyncis|ψ<sup>10</sup>]], although according to the modern IAU constellation boundaries, ψ<sup>10</sup> lies in [[Lynx (constellation)|Lynx]]).