page_title: Revised Julian calendar
section_title: March equinox
hierarchical_section_title: Revised Julian calendar / March equinox
caption_attribution_description: English: Depicts the numerically integrated northward equinox relationship for the Revised Julian calendar, computed for Jerusalem Local Apparent Time.
context_page_description: The Revised Julian calendar, also known as the Milanković calendar, or, less formally, new calendar, is a calendar proposed by the Serbian scientist Milutin Milanković in 1923, which effectively discontinued the 340 years of divergence between the naming of dates sanctioned by those Eastern Orthodox churches adopting it and the Gregorian calendar that has come to predominate worldwide. This calendar was intended to replace the ecclesiastical calendar based on the Julian calendar hitherto in use by all of the Eastern Orthodox Church. From 1 March 1600 through 28 February 2800, the Revised Julian calendar aligns its dates with the Gregorian calendar, which was proclaimed in 1582 by Pope Gregory XIII for adoption by the Christian world. The calendar has been adopted by the Orthodox churches of Constantinople, Albania, Alexandria, Antioch, Bulgaria, Cyprus, Greece, and Romania.
  The Revised Julian calendar has the same months and month lengths as the Julian calendar, but, in the Revised Julian calendar, years evenly divisible by 100 are not leap years, except that years with remainders of 200 or 600 when divided by 900 remain leap years, e.g. 2000 and 2400 as in the Gregorian Calendar.
context_section_description: The following is a scatter plot of actual astronomical northward equinox moments as numerically integrated by SOLEX 11 using DE421 mode with extended (80-bit) floating point precision, high integration order (18th order), and forced solar mass loss ("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 1 January 2000 at noon (J2000.0 epoch). The progressive tidal slowing of the Earth rotation rate was accounted for by subtracting ΔT as calculated by the Espenak-Meeus polynomial set recommended at the NASA Eclipses web site to obtain the J2000.0-relative Universal Time moments, which were then properly converted to Revised Julian dates and Jerusalem 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 ΔT is expected to accumulate to about six hours, with an uncertainty of less than ​2 ¹⁄₂ hours.
  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.
caption: Equinox-Revised-Julian-Jerusalem-SOLEX-11
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