CALENDAR CONVERSIONS
This application converts dates between Julian, Gregorian, Hebrew and French Calendars
and Julian Date. The type Calendar corresponds to today's Gregorian Calendar.
The year 0 in the Julian and Gregorian Calendars corresponds to 1 B.C.
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- Julian dates may be applied both before the calendar
was invented (proleptic) and after it was replaced as long as it is clear
that the Julian leap year rules are being applied. The Julian calendar is
used for dates on or before October 04, 1582. Gregorian
dates may be applied before the Gregorian calendar was invented (proleptic)
as long as it is clear that the Gregorian calendar leap year rules are being
applied. The Gregorian calendar is used for dates on or after October 15,
1582.
- The difference between the Julian and today's Gregorian calendar is that
the Gregorian does not make centennial years leap years unless they are a
multiple of 400.
- The Julian Day Number or JD of a particular instant
of time is the number of days and fractions of a day since 12 hours Universal
Time (Greenwich mean noon) on January 1, -4712, in the Julian proleptic calendar.
- The Hebrew calendar is the official calendar of
Israel and it is the liturgical calendar of the Jewish faith. Years are counted
from the Era of Creation, or Era Mundi, which corresponds to -3760 October
7 on the Julian proleptic calendar.
Days of the week are designated by number, with only the seventh day, Sabbath,
having a specific name. Days are reckoned from sunset to sunset, so that day
1 begins at sunset on Saturday and ends at sunset on Sunday. The Sabbath begins
at sunset on Friday and ends at sunset on Saturday. For calendrical calculations,
the day begins at 6 P.M., which is designated 0 hours. Hours are divided into
1080 halakim; thus one helek is 3 1/3 seconds. Calendrical calculations are
referred to the meridian of Jerusalem -- 2 hours 21 minutes east of Greenwich.
- The French calendar was adopted in October 1793
and was abandoned in January 1806.
- Julian and Gregorian conversion routines from Peter Baum http://www.capecod.net/~pbaum/
. Hebrew and French conversion routines from Scott E. Lee http://genealogy.org/~scottlee/
. Easter algorithm and other calendar information http://astro.nmsu.edu/~lhuber/leaphist.html
- Although the algorithms are from the sources above, I have no idea if the
JavaScript code is correct. If you have any comments or corrections, please
send an e-mail to jonnie@newyorkcity.com
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