This webpage belongs to www.alexandriancomputus.net, which is a website promoting [Jan Zuidhoek (2019) Reconstructing Metonic 19-year Lunar Cycles (on the basis of NASA’s Six Millennium Catalog of Phases of the Moon): Zwolle], and reproduces the table containing the five Alexandrian Metonic 19‑year lunar cycles being part of this pioneering book, which is available via this website.

Five Alexandrian Metonic 19-year Lunar Cycles
AD	Anatolius’	archetyp. Alex.	Festal Index	Theophilus’	classic. Alex.
304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322	8 April 28 March 16 April 5 April 24 March 12 April 1 April 20 April 9 April 29 March 17 April 6 April 26 March 14 April 3 April 23 March 11 April 31 March 19 April	6 April 26 March 13 April 2 April 22 March 10 April 30 March 18 April 7 April 27 March 15 April 4 April 24 March 12 April 1 April 21 March 9 April 29 March 17 April	6 April 26 March 14 April 2 April 22 March 10 April 30 March 18 April 7 April 27 March 15 April 4 April 24 March 12 April 1 April 21 March 9 April 29 March 17 April	6 April 26 March 13 April 2 April 22 March 10 April 30 March 18 April 7 April 27 March 15 April 4 April 24 March 12 April 1 April 21 March 9 April 29 March 17 April	5 April 25 March 13 April 2 April 22 March 10 april 30 March 18 April 7 April 27 March 15 April 4 April 24 March 12 April 1 April 21 March 9 April 29 March 17 April
Table 8: Comparing the two lost (but reconstructed) ante-Nicene and the three well‑known post‑Nicene Alexandrian Metonic 19-year lunar cycles to each other

Anatolius’ 19-year lunar cycle is the lost Metonic 19‑year lunar cycle from which the great Alexandrian computist Anatolius, who became bishop of Laodicea (Syria), around AD 260 started in order to construct his famous 19‑year Paschal cycle. The archetypal Alexandrian 19-year lunar cycle, also simply referred to as the archetypal Alexandrian cycle, is the lost ante‑Nicene common archetype of the three well-known post‑Nicene Alexandrian Metonic 19‑year lunar cycles. Both of these Metonic 19‑year lunar cycles were both constructed (before the council of Nicaea in AD 325) and reconstructed (recently) mutatis mutandis according to four computistical principles: the principle concerning the spring equinox, the principle concerning the crescent moon, the principle of periodicity, and the principle of metonicity.

The Festal Index 19-year lunar cycle, also simply referred to as the Festal Index cycle, must have been obtained from the archetypal Alexandrian cycle by replacing its date 13 April with 14 April. Theophilus’ 19-year lunar cycle must have been obtained by bishop Theophilus of Alexandria by adopting the archetypal Alexandrian cycle or by adapting the Festal Index cycle by replacing its date 14 April with 13 April.

The classical Alexandrian 19-year lunar cycle, also simply referred to as the classical Alexandrian cycle, is Annianus’ 19-year lunar cycle, being the Metonic 19‑year lunar cycle opted for by the Alexandrian monk and great computist Annianus (around AD 412) and subsequently adopted by bishop Cyril of Alexandria (around AD 425). The classical Alexandrian cycle forms the Metonic structure underlying both Dionysius Exiguus’ Paschal table (AD 525) and the Easter table of Beda Venerabilis (AD 725).

We observe that there exists a gap of about 2 days between on the one hand Anatolius’ 19-year lunar cycle and on the other hand the other four Alexandrian Metonic 19-year lunar cycles; this gap dates from before the council of Nicaea in AD 325, and is therefore referred to as the ante-Nicene Alexandrian 2‑day gap.

back to homepage

Five Alexandrian Metonic 19-year Lunar Cycles