Editing Stellar designations and names (section)

== Catalogue designations ==

In the absence of any better means of designating a star, catalogue designations are generally used. Many star catalogues are used for this purpose; see [[star catalogue]]s.

===By constellation===
The first modern schemes for designating stars systematically labelled them within their constellation.

*The [[Bayer designation]] is such a system, published by [[Johann Bayer]] in 1603.<ref>{{cite web|url=http://www.ianridpath.com/startales/bayer.htm|title=Bayer's Uranometria and Bayer letters|publisher=Ian Ridpath|access-date=2016-11-12}}</ref> It introduced a system of designating the brightest stars in each constellation by means of Greek (or less often Latin) letters, and is still widely used. Bayer generally assigned letters by magnitude class: 1st magnitude stars received the earliest letters in the alphabet, followed by 2nd magnitude stars, and so forth (though there are many exceptions).  The original list of Bayer designations contained 1,564 naked-eye stars, and several stars not catalogued by Bayer have been added by subsequent astronomers.
*The [[Flamsteed designation]] also lists stars by constellation, but by number rather than letter, ordering them by increasing right ascension rather than by decreasing brightness. These numbers were assigned not by Flamsteed himself but by the French astronomer J. J. Lalande in a French edition of Flamsteed's catalogue published in 1783.<ref>{{cite web|url=http://www.ianridpath.com/startales/flamsteed.htm|title=Flamsteed numbers – where they really came from|publisher=Ian Ridpath|access-date=2016-11-12}}</ref>
*The [[Gould designation]] for stars visible from the southern hemisphere, introduced by [[Benjamin Gould]] (1879), also lists stars by constellation, numbered by increasing right ascension.
*[[Hevelius]] and [[Johann Elert Bode|Bode]] both numbered stars within constellations similarly. Their number systems have fallen out of use, but their designations even now are occasionally mistakenly treated as Flamsteed designations.  [[47 Tucanae]], a number assigned by Bode, is a famous example.

===Full-sky catalogues===
Full-sky [[star catalogues]] detach the star designation from the star's constellation and aim at enumerating all stars with apparent magnitude greater than a given cut-off value.

*The ''[[Histoire céleste française]]'' (1801) enumerated  47,390 stars to magnitude 9.
*The ''[[Bonner Durchmusterung]]'' (1859) was the most complete star catalogue compiled without the aid of photography. It listed a total of 320,000 northern stars, expanded by the ''Cordoba Durchmusterung'' (1892) and the ''Cape Photographic Durchmusterung'' (1896).
*The ''[[Henry Draper Catalogue]]'' (1924) listed 225,300 stars to magnitude 10, extended to a total of 359,083 in 1949. The HD numbers remain in widespread use for stars that do not have a Flamsteed or Bayer designation.
*The ''[[Bright Star Catalogue]]'' of 1930 listed all stars brighter than magnitude 6. It was supplemented to include stars down to magnitude 7.1 in 1983.
*The ''Catalogue astrographique'' was compiled between 1891 and 1950 with the aim of listing all stars to magnitude 11, resulting in a list of 4.6 million stars. It is under continued development, now under custody of the [[U.S. Naval Observatory]].
*The USNO-B1.0 catalogue contains over a billion objects, and is also under continued development at the  U.S. Naval Observatory.
*The online ''[[Guide Star Catalog|Guide Star Catalog II]]'' (2008) contains 945 million stars to magnitude 21.

=== Variable designations ===
{{main article|Variable star designation}}
Variable stars that do not have Bayer designations are assigned designations in a variable star scheme that superficially extends the Bayer scheme with uppercase Latin letters followed by constellation names, starting with single letters R to Z, and proceeding to pairs of letters. Such designations mark them as variable stars. Examples include [[R Cygni]], [[RR Lyrae]], and [[28 Andromedae|GN Andromedae]]. (Many variable stars also have designations in other catalogues.)

=== Exoplanet searches ===

When a planet is detected around a star, the star is often given a name and number based on the name of the telescope or survey mission that discovered it and based on how many planets have already been discovered by that mission e.g. [[HAT-P-9]], [[WASP-1]], [[COROT-1]], [[Kepler-4]], [[TRAPPIST-1]].