Designation Systems
The naming schemes that label the stars themselves — Bayer letters, Flamsteed numbers, and variable-star designations.
- Bayer DesignationDesignation systemα · 1603
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.
- Flamsteed DesignationDesignation system61 · 1725
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.
- Variable-Star DesignationDesignation systemR
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.