Editing Revised Julian calendar (section)

==March equinox==
The following is a [[scatter plot]] of actual astronomical [[northward equinox]] moments as [[numerical integration|numerically integrated]] by SOLEX 11{{sfn|Vitagliano |1997|pp=293-308}}<ref>{{cite web |url= http://main.chemistry.unina.it/~alvitagl/solex/ |title= The SOLEX home page |url-status= dead |archive-url= https://web.archive.org/web/20110403085028/http://main.chemistry.unina.it/~alvitagl/solex/ |archive-date= 3 April 2011}}</ref> using DE421 mode{{sfn|Folkner|Williams|Boggs|2008}} with extended (80-bit) [[floating point]] precision, high integration order (18th order), and forced solar mass loss{{sfn|Noerdlinger|2008|p=}} ("forced" means taken into account at all times). SOLEX can automatically search for northern hemisphere spring equinox moments by finding when the solar [[declination]] crosses the [[celestial equator]] northward, and then it outputs that data as the [[Terrestrial Time]] day and fraction of day relative to {{nowrap|1 January 2000}} at noon ([[J2000#Julian years and J2000|J2000.0]] epoch). The progressive [[Tidal acceleration|tidal slowing of the Earth rotation rate]] was accounted for by subtracting [[ΔT (timekeeping)|Δ''T'']] as calculated by the [[Fred Espenak|Espenak]]-[[Jean Meeus|Meeus]] polynomial set recommended at the NASA Eclipses web site<ref>{{cite web |url= http://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html |publisher= NASA |title= Eclipses Delta T web site}} Gives the Espenak-Meeus polynomial expressions for Delta T.</ref> to obtain the J2000.0-relative [[Universal Time]] moments, which were then properly converted to Revised Julian dates and Jerusalem [[Solar time|local apparent time]], taking local apparent midnight as the beginning of each calendar day. The year range of the chart was limited to dates before the year AD 4400: by then Δ''T'' is expected to accumulate to about six hours, with an uncertainty of less than {{frac|2|1|2}} hours.<ref>{{cite web |url= http://eclipse.gsfc.nasa.gov/SEcat5/uncertainty.html |title= Uncertainty in Delta ''T'' (Δ''T'')}}</ref>

[[File:Equinox-Revised-Julian-Jerusalem-SOLEX-11.png|thumb|Equinox-Revised-Julian-Jerusalem-SOLEX-11]]

The chart shows that the long-term equinox drift of the Revised Julian calendar is quite satisfactory, at least until AD 4400. The medium-term wobble spans about two days because, like the Gregorian calendar, the leap years of the Revised Julian calendar are not smoothly spread: they occur mostly at intervals of four years but there are occasional eight-year gaps (at 7 out of 9 century years). Evidently each of the authorities responsible for the Gregorian and Revised Julian calendars, respectively, accepted a modest amount of medium-term equinox wobble for the sake of traditionally perceived leap rule mental arithmetic simplicity. Therefore, the wobble is essentially a curiosity that is of no practical or ritual concern.