Editing Astronomical naming conventions (section)

=== Supernovae ===
{{see also|Supernova#Naming convention|l1=Naming and classification of supernovae}}

[[Supernova]] discoveries are reported to the IAU's ''[[Central Bureau for Astronomical Telegrams]]'' and are automatically given a provisional designation based on the co-ordinates of the discovery. Historically, when supernovae are identified as belonging to a "type", CBAT has also published circulars with assigned year–letter designations, and discovery details. A supernova's permanent designation is formed by the standard prefix "SN", the year of discovery, and a suffix composed of one to three letters of the Latin alphabet. The first 26 supernovae of the year receive a capital letter from ''A'' to ''Z''. Subsequent supernovae of that year are designated with pairs of lower-case letters from "aa" to "az", and then continuing with "ba" until "zz". Then come "aaa", "aab", and so on (this first occurred in 2015-2016)<!-- Asiago Supernova Catalogue for 2015 (http://graspa.oapd.inaf.it/cgi-bin/sncat_new.cgi?yr=2015) runs up to 2015dd and then jumps to 2016aai, 2016dpd, and 2016fq -->. For example, the prominent [[SN&nbsp;1987A]], was the first one to be observed in 1987, while [[SN 2023ixf]] was one of the brightest ever observed in recent times. Several thousand supernovae have been reported since 1885.<ref name="cbat-SN-list" /> In recent years, several supernova discovery projects have retained their more distant supernova discoveries for in-house follow-up, and not reported them to CBAT. Starting in 2015, CBAT has scaled back its efforts to publish assigned designations of typed supernovae: By September 2014, CBAT had published names and details of 100 supernovae discovered in that year. By September 2015, CBAT had only published names of 20 supernovae discovered in that year. The [[Astronomer's Telegram]] provides some surrogate services independent from CBAT.

Four historical supernovae are known simply by the year they occurred: [[SN&nbsp;1006]] (the brightest stellar event ever recorded), [[SN&nbsp;1054]] (of which the remnant is the [[Crab Nebula]] and the [[Crab Pulsar]]), [[SN&nbsp;1572]] (''Tycho's Nova''), and [[SN&nbsp;1604]] (''Kepler's Star'').

Since 1885, the letter-suffixes are explicitly assigned, regardless whether only one supernova is detected during the entire year (although this has not occurred since 1947). Driven by advances in technology and increases in observation time in the early 21st century, hundreds of supernovae were reported every year to the IAU, with more than 500 catalogued in 2007.<ref name="cbat-SN-list">{{cite web|url=http://cbat.eps.harvard.edu/lists/Supernovae.html |title=List of Supernovae |publisher=Cbat.eps.harvard.edu |access-date=4 September 2015}}</ref> Since then, the number of newly discovered supernovae has increased to thousands per year, for example almost 16,000 supernovae observations were reported in 2019, more than 2,000 of which were named by CBAT.<ref>{{cite web |last=Bishop |first=David |title=Supernova discovery statistics for 2019 |url=http://www.rochesterastronomy.org/sn2019/snstats.html |archive-url=https://web.archive.org/web/20201120085934/http://www.rochesterastronomy.org/sn2019/snstats.html |archive-date=2020-11-20 |access-date=14 March 2021 |publisher=Rochester Academy of Science, Astronomy Section}}</ref>