Editing List of non-standard dates (section)

==Historical==
===January 0===
'''January 0''' is an alternative name for [[December 31]]. January 0 is the day before [[January 1]] in an annual [[ephemeris]]. It keeps the date in the year for which the ephemeris was published, thus avoiding any reference to the previous year, even though it is the same day as [[December 31]] of the previous year. January 0 also occurs in the [[Epoch (astronomy)|epoch]] for the [[Second#Fraction of an ephemeris year|ephemeris second]], "1900 January 0 at 12 hours ephemeris time".<ref name="USNO">{{cite web|title=Leap Seconds |publisher=Time Service Department, [[United States Naval Observatory]] |url=http://tycho.usno.navy.mil/leapsec.html |access-date=December 31, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20120228195938/http://tycho.usno.navy.mil/leapsec.html |archive-date=February 28, 2012 }}</ref> 1900 January 0 (at Greenwich Mean Noon) was also the epoch used by [[Newcomb's Tables of the Sun|Newcomb's ''Tables of the Sun'']], which became the epoch for the [[Julian day#Variants|Dublin Julian day]].<ref>{{cite web|url=https://textfiles.meulie.net/computers/DOCUMENTATION/astroclk.dc2 |title=Program ASTROCLK: Astronomical Clock and Celestial Tracking Program with Celestial Navigation | first=David H. Jr. | last=Ransom |date=November 19, 1989 |page=110}}</ref>

===February 30===
{{see also|Swedish calendar}}
[[File:feb1712.jpg|thumb|right|300px|Swedish calendar for February 1712]]

'''February 30''' is a day that does not occur on the [[Gregorian calendar]], where the month of [[February]] contains only 28 days, or 29 days in a [[leap year]]. However, from a historical perspective February 30 has been used at least once and appears in some [[#Reform calendars|reform calendars]].

The thirteenth-century scholar [[Johannes de Sacrobosco]] claimed that in the [[Julian calendar#Sacrobosco's incorrect theory on month lengths|Julian calendar]], [[February]] had 30 days in leap years from 45 BC until 8 BC, when [[Caesar Augustus|Augustus]] allegedly shortened [[February]] by one day to give that day to the month of [[August]] named after him so that it had the same length as the month of [[July]] named after his adoptive father, [[Julius Caesar]]. However, all historical evidence refutes [[Johannes de Sacrobosco|Sacrobosco]], including dual dates with the [[Coptic calendar|Alexandrian calendar]].<ref>Roscoe Lamont, "[http://articles.adsabs.harvard.edu//full/1919PA.....27..579P/0000583.000.html The Roman calendar and its reformation by Julius Caesar]", ''[[Popular Astronomy (US magazine)|Popular Astronomy]]'' '''27''' (1919) 583–595. Sacrobosco's theory is discussed on pages 585–587.</ref>

February 30 was a day that happened in [[Sweden]] in 1712.<ref name = timeanddate>{{cite web
 |url=http://www.timeanddate.com/date/february-30.html
 |title=February 30 Was a Real Date
 |publisher=timeanddate.com
 |access-date=2024-07-11
 |first=Vigdis
 |last=Hocken
 |url-status=live
 |archive-url=https://web.archive.org/web/20240329043659/https://www.timeanddate.com/date/february-30.html
 |archive-date=2024-03-29
}}</ref> This occurred because, instead of changing from the [[Julian calendar]] to the [[Gregorian calendar]] by omitting a block of consecutive days, as had been done in other countries, the [[Swedish Empire]] planned to change gradually by omitting all [[leap day]]s from 1700 to 1740, inclusive, so that the next leap year after 1696 would not be until 1744. Although the leap day was omitted in February 1700, the [[Great Northern War]] began later that year, diverting the attention of the Swedes from their calendar so that they did not omit leap days on the next two occasions; 1704 and 1708 remained leap years.<ref name="Bauer">{{cite book|last1=Bauer|first1=R. W.|title=Calender for Aarene fra 601 til 2200|date=1868|location=Copenhagen, Denmark|publisher=Dansk Historisk Fællesråd (1993 reprint)|isbn=87-7423-083-2|page=100}}</ref>

To avoid confusion and further mistakes, the [[Julian calendar]] was restored in 1712 by adding a second leap day, thus giving that year the only known actual use of February 30 in a calendar. That day corresponded to February 29 in the [[Julian calendar]] and to March 11 in the [[Gregorian calendar]].<ref name="Bauer"/><ref>{{cite book|last1=Vallerius|first1=Johannes|title=Allmanach på åhret effter Christi födelse 1712|date=1711|location=Lund, Sweden}}</ref> The Swedish conversion to the [[Gregorian calendar]] was finally accomplished in 1753, when February 17 was followed by March 1.<ref name="Bauer"/>

Artificial calendars may also have 30 days in [[February]]. For example, in a climate model the statistics may be simplified by having 12 months of 30 days. The [[Hadley Centre]] General Circulation Model is an example.<ref>{{cite web|url=http://www.metoffice.com/research/hadleycentre/models/GDT/ch23.html|title=Hadley Centre: GDT netCDF conventions|date=November 22, 2005|work=MetOffice.com|access-date=March 21, 2017|url-status=dead|archive-url=https://web.archive.org/web/20051122015007/http://www.metoffice.com/research/hadleycentre/models/GDT/ch23.html|archive-date=November 22, 2005}}</ref>

===May 35===
'''May 35''' is used in the title of ''[[The 35th of May, or Conrad's Ride to the South Seas]]'', a German children's novel published in 1932.{{cn|date=March 2025}}

===July 36===
{{Main|July 36}}
'''July 36''' refers to 5 August 2024, when the Bangladesh [[2024 Bangladesh quota reform movement|quota reform movement]] celebrated Prime Minister [[Sheikh Hasina]] resigning and fleeing to India after mass protests, which began with the reinstatement of the quota system in June and escalated despite the Supreme Court's ruling on 21 July in favor of quota reform.<ref>{{Cite web |date=2024-12-01 |title='Bangladesh Reborn: Pathway to July 36' photo exhibition by BJIM starts tomorrow |url=https://www.tbsnews.net/events/bangladesh-reborn-pathway-july-36-photo-exhibition-bjim-starts-tomorrow-1007386 |access-date=2024-12-04 |website=The Business Standard |language=en}}</ref><ref>{{Cite web |title=Photo exhibition 'Saluting the Brave Hearts, 36 days of July' inaugurated |url=https://www.dhakatribune.com/bangladesh/event/366734/photo-exhibition-%E2%80%98saluting-to-brave-hearts-36 |access-date=2024-12-04 |website=Dhaka Tribune |language=en}}</ref><ref>{{Cite web |date=2024-08-20 |title='New Bangladesh', '36 July': Artworks grow on Dhaka walls to memorialise protests |url=https://www.mid-day.com/news/world-news/article/new-bangladesh-36-july-artworks-grow-on-dhaka-walls-to-memorialise-protests-23377626 |access-date=2024-12-04 |website=Mid-day |language=en}}</ref>

===December 31.5 GMT===
{{see also|Greenwich Mean Time#Ambiguity in the definition of GMT}}
'''December 31.5 GMT''' in 1924 almanacs was an instant defined to resolve the contrast between two different conventions in defining the [[civil time]] of referring to midnight as zero hours.<ref>{{cite book |title=Astronomical Supplement to the Astronomical Almanac |publisher=University Science Books |year=1992 |isbn=0-935702-68-7 |page=76}}</ref>

===December 32===
The [[LearAvia Lear Fan]] aircraft test flight had British government funding that expired at the end of that year. After the cancellation of a planned test flight on December 31, 1980, due to technical issues, the first prototype made its maiden flight on January 1, 1981, but a sympathetic government official recorded the date as "December 32, 1980".<ref>{{cite web |url=http://www.museumofflight.org/aircraft/lear-fan-2100-futura|title=Lear Fan 2100 (Futura) |archive-url=https://web.archive.org/web/20090712041304/http://museumofflight.org/aircraft/lear-fan-2100-futura |archive-date=July 12, 2009 |work=The Museum of Flight |date=2009 |access-date=November 27, 2009}}</ref>