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This webpage is part of www.alexandriancomputus.net,
which supports the new book on early Alexandrian Paschal reckoning
[Jan Zuidhoek (2023) Reconstructing Alexandrian Lunar Cycles (on the basis of
Espenak’s Six Millennium Catalog of Phases of the Moon): Zwolle]. This
webpage consists of a short description of the content of this new book,
which is available via this website,
and a very concise curriculum vitae of its author. |
This book explains, by following the
mainstream of the history of computus (i.e. Paschal reckoning developed from
early third century for determining Julian or Alexandrian calendar dates of
Paschal Sunday) which shortly after AD 250 rose in Alexandria (Egypt) to
ultimately in AD 1582 (turning point in the history of chronology) flow
into an astronomically more realistic method for determining Gregorian calendar
dates of Easter, how at the time in Alexandria calendar dates of Paschal Sunday
depended on phases of the moon and how recently the three lost important
Metonic lunar cycles constructed in Alexandria before the first council of
Nicaea in AD 325 (turning point in the history of Christianity) were
reconstructed by the author of this book on the basis of the Six Millennium
Catalog of Phases of the Moon compiled by NASA’s eclipse expert Fred Espenak.
The author of this book 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 Gymnasium Celeanum in Zwolle. After having gone deeply
into the history of chronology and of early Christianity, which resulted in his webpages “Christian Era and Universal Time”
and “Dionysius
Exiguus’ Paschal Table”, he became fascinated by the
Alexandrian computus. In 2009 he succeeded, using the Six Millennium Catalog,
in reconstructing the lost predecessor of the lost Metonic lunar cycle
underlying the famous 19‑year Paschal cycle of the great third century Alexandrian computist
Anatolius which had survived as a part of the third or fourth century Latin
text De ratione paschali. The two
presentations he gave at international conferences on the science of computus
at the university of Galway in 2010 and in 2018 resulted in 2017 in a
pioneering article, entitled “The initial year of De ratione paschali
and the relevance of its paschal dates”, and in 2019 in his first book (ISBN 9789090324678), entitled “Reconstructing Metonic
19 year Lunar Cycles”, reducing the article to a preparatory study. This new
book (ISBN 9789090370446) was developed from the revised edition of his first
book.
© Jan Zuidhoek 2023‑2025