> 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).
> 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
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.