**Concise**** Curriculum Vitae**

**Jan Zuidhoek was born in 1938, studied mathematics, physics, and astronomy at the university of
Utrecht from 1960 to 1969,
and was a teacher of mathematics from
1970 to 2001 at the Gymnasium Celeanum
in Zwolle. After having gone deeply into
the fields of history of mathematics, chronology, and history of early Christianity, he became fascinated by the Alexandrian computus, i.e. the Alexandrian form of the computus paschalis being the science developed from the beginning of the third century on
behalf of the determination
of the date of Paschal Sunday.
In 2009 he succeeded, by using NASA’s
Six Millennium Catalog of Phases of the Moon, in determining the initial year (AD 271) of De ratione paschali, i.e. the medieval Latin text containing the legendary 19-year Paschal cycle of Anatolius, the famous third century
Alexandrian computist who invented the very first Metonic
19‑year lunar cycle.
The underlying reconstruction
of the so called proto-Alexandrian 19‑year lunar
cycle was the subject of the presentation
he gave at the international conference on the science of computus which took place at the university of Galway in 2010. This presentation resulted in his article entitled
“The initial year of De ratione paschali and the relevance of
its paschal dates”, which was published in 2017 in
the proceedings of that
conference. The presentation he
gave at a similar conference in 2018 led to this book,
in which he describes not only
his reconstruction of both lost Alexandrian Metonic 19-year lunar cycles supposed to be constructed
some time before the first council of Nicaea (AD 325), turning point in the history of Christianity, but also the development from the second of them to the particular
Metonic 19-year lunar cycle from which
thirteen centuries later the
Italian astronomer Luigi Lilio and subsequently the German mathematician Christoph Clavius would develop
a modern, astronomically more correct, system for determining
the Gregorian calendar date
of Easter Sunday.**

**© Jan Zuidhoek 2019‑2021**