Re: Western Metonic Cycle

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Re: Western Metonic Cycle

Peter Meyer
Walter said:

> The Julian Day system is based on the Easter cycle

Scaliger's invention of the Julian Period of 7980 years is based in
part on the number of years (19) in the Metonic Cycle.  (7980 is the
least common multiple of 28, 19 and 15.)  The "Easter cycle" is also
based on the Metonic Cycle.  But this does not imply that Scaliger's
Julian Period is based on the Easter cycle.

The Julian Day Number system was not part of, or implied by, Scaliger's
invention.  That system was invented in 1849 (or earlier) by the
astronomer John W. F. Herschel, who defined "Julian Day Number" as the
number of days since the first day of Scaliger's Julian Period, namely,
-4712-01-01 JC (which is JDN 0).

For more on this see "Julian Day Numbers" at
https://www.hermetic.ch/cal_stud/jdn.htm

Regards,
Peter
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Re: Western Metonic Cycle

Walter J Ziobro

Dear Peter et al

Thank you for clarifying that

It is interesting to note that the beginning of the Julian Date system is 248 Metonic cycles before Julian year 1 BC

WalterZiobro




On Friday, March 22, 2019 Peter Meyer <[hidden email]> wrote:

Walter said:

> The Julian Day system is based on the Easter cycle

Scaliger's invention of the Julian Period of 7980 years is based in
part on the number of years (19) in the Metonic Cycle.  (7980 is the
least common multiple of 28, 19 and 15.)  The "Easter cycle" is also
based on the Metonic Cycle.  But this does not imply that Scaliger's
Julian Period is based on the Easter cycle.

The Julian Day Number system was not part of, or implied by, Scaliger's
invention.  That system was invented in 1849 (or earlier) by the
astronomer John W. F. Herschel, who defined "Julian Day Number" as the
number of days since the first day of Scaliger's Julian Period, namely,
-4712-01-01 JC (which is JDN 0).

For more on this see "Julian Day Numbers" at

Regards,
Peter
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Re: Western Metonic Cycle

Peter Meyer
In reply to this post by Peter Meyer
Walter said:

> It is interesting to note that the beginning of the Julian Date
> system is 248 Metonic cycles before Julian year 1 BC

Yes. Karl might be able to throw light on the esoteric significance of this.

But strictly speaking there's no "Julian Date system".  There is,
however, a "Julian Day Number system". There's also a "Julian date",
which term can refer either to a date in the Julian Calendar (which is
the more common meaning) or a real number whose integer part is a
Julian Day Number.  For more see
https://www.hermetic.ch/cal_stud/jdn.htm#different_meanings

Regards,
Peter
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Re: Western Metonic Cycle

k.palmen@btinternet.com
In reply to this post by Walter J Ziobro
Dear Walter and Calendar People

The Julian Day epoch was chosen to the start of the Julian Calendar year (Jan 1) whose Golden number is 1 and so this is no surprise. It was also chosen to be at the start of the 28-year Solar Cycle (better named Sunday cycle) and the 15-year indiction cycle.

Karl

Monday Delta March 2019
----Original message----
From : [hidden email]
Date : 22/03/2019 - 13:28 (GMT)
To : [hidden email]
Subject : Re: Western Metonic Cycle

Dear Peter et al

Thank you for clarifying that

It is interesting to note that the beginning of the Julian Date system is 248 Metonic cycles before Julian year 1 BC

WalterZiobro




On Friday, March 22, 2019 Peter Meyer <[hidden email]> wrote:

Walter said:

> The Julian Day system is based on the Easter cycle

Scaliger's invention of the Julian Period of 7980 years is based in
part on the number of years (19) in the Metonic Cycle.  (7980 is the
least common multiple of 28, 19 and 15.)  The "Easter cycle" is also
based on the Metonic Cycle.  But this does not imply that Scaliger's
Julian Period is based on the Easter cycle.

The Julian Day Number system was not part of, or implied by, Scaliger's
invention.  That system was invented in 1849 (or earlier) by the
astronomer John W. F. Herschel, who defined "Julian Day Number" as the
number of days since the first day of Scaliger's Julian Period, namely,
-4712-01-01 JC (which is JDN 0).

For more on this see "Julian Day Numbers" at

Regards,
Peter