Dear Frank,
... ANSI Standard Easter, I missed it, I hope none of the international
authorities for the standards read this mailing-list :-)
Even Gauss took care of it but his algorithm doesn't manage some exceptions.
For those interested in the matter:
Algorithm to calculate the date of Easter, by Spencer Jones, from his
book General Astronomy, pages 73-74, edition of 1922.
Published again in the Journal of the British Astronomical Association,
vol. 88, page 91, december 1977.
Here it is reported that the algorithm was defined on 1876 and it
appeared in the Butcher's Ecclesiastical Calendar.
Unlike the algorithm of Gauss, this hasn't exceptions and it runs for
the Gregorian Calendar, starting from 1583.
The limits of the dates are march 22 and april 25.
The dates of Easter have a cycle of 5,700,000 years.
The most frequently date is april 19.
Example for 2019:
A=5, B=20, C=19, D=5, E=0, F=1, G=6, H=29, J=4, K=3, L=1, M=0, N=4, P=20
N=4 that is april, P+1=21
The Orthodox Easter follows the Julian Calendar, the algorithm is:
The cycle of the dates of the Julian Easter is 532 years.
Example for 2019:
A=3, B=3, C=5, D=20, E=4, F=4, G=14
N=4 april, G+1=15, in the Gregorian Calendar 15+13=28
ciao Fabio
Il 21/03/2019 15:35, Frank King ha scritto:
Dear Roger,
I note that you say:
My reference on this topic is The Sun in
the Church by J L Heilbron.
He is pretty sound on this and, as early
as page 3, notes that the time of the
equinox and the time of full moon depend
where you are on the planet. He adds,
"as, of course does Sunday".
If everyone used the Julian Date then
they might all agree on the instant of
the equinox and the instant of full
moon but it seems most unlikely that
they would have similar agreement as
to what is meant by "Sunday".
It takes 48 hours from the start of a
given Sunday, just to the west of the
International Date Line, to the end of
the same Sunday, just to the east of
the Line.
Fabio has pointed out that Rome and
Jerusalem have been suggested as
candidate places for defining a
Canonical Sunday. I too have read
this but I don't know where the
supposed primary source is.
I think Fabio's explanation is the
most plausible. In essence, you
define an algorithm (albeit one
that is a bit suspect) and impose
a kind of ANSI Standard Easter :-)
As a former colleague once told me:
"The great thing about having Standards
is that there are so many of them."
You are one of the most-westerly
subscribers to this list so I think
a Bailey-Standard Easter would be
worth lobbying for.
You might thereby become a noted
Holy Man. Be careful!
Very best wishes
Frank
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Fabio Savian
fabio.sav...@nonvedolora.it
www.nonvedolora.eu
Paderno Dugnano, Milano, Italy
45° 34' 9'' N, 9° 9' 54'' E, UTC +1 (DST +2)
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