Editing IAU designated constellations (section)

=== Abbreviations ===
Each IAU constellation has an official three-letter abbreviation based on the [[genitive]] form of the constellation name. As the genitive is similar to the base name, the majority of the abbreviations are just the first three letters of the constellation name: ''Ori'' for ''Orion/Orionis'', ''Ara'' for ''Ara/Arae'', and ''Com'' for ''Coma Berenices/Comae Berenices''. In some cases, the abbreviation contains letters from the genitive not appearing in the base name (as in ''Hyi'' for ''Hydrus/Hydri'', to avoid confusion with ''Hydra'', abbreviated ''Hya''; and ''Sge'' for ''Sagitta/Sagittae'', to avoid confusion with ''Sagittarius'', abbreviated ''Sgr''). Some abbreviations use letters beyond the initial three to unambiguously identify the constellation (for example when the name and its genitive differ in the first three letters): ''Aps'' for ''Apus/Apodis'', ''CrA'' for ''Corona Australis'', ''CrB'' for ''Corona Borealis'', ''Crv'' for ''Corvus''. (''Crater'' is abbreviated ''Crt'' to prevent confusion with ''CrA''.) When letters are taken from the second word of a two-word name, the first letter from the second word is capitalised: ''CMa'' for ''Canis Major'', ''CMi'' for ''Canis Minor''. Two cases are ambiguous: ''Leo'' for the constellation ''Leo'' could be mistaken for ''Leo Minor'' (abbreviated ''LMi''), and ''Tri'' for ''Triangulum'' could be mistaken for ''Triangulum Australe'' (abbreviated ''TrA'').<ref>{{cite journal|bibcode=1922PA.....30..469R|title=The New International Symbols for the Constellations|journal=Popular Astronomy|volume=30|pages=469|last1=Russell|first1=Henry Norris|year=1922}}</ref>

In addition to the three-letter abbreviations used today, the IAU also introduced four-letter abbreviations in 1932. The four-letter abbreviations were repealed in 1955 and are now obsolete, but were included in the NASA Dictionary of Technical Terms for Aerospace Use (NASA SP-7) published in 1965.<ref>{{cite web |url=http://www.ianridpath.com/constellations1.html |title=Constellations |publisher=[[Ian Ridpath]] |access-date=30 January 2023 |archive-date=16 July 2023 |archive-url=https://web.archive.org/web/20230716100455/http://www.ianridpath.com/constellations1.html |url-status=live }}</ref> These are labeled "NASA" in the table below and are included here for reference only.