#15 Julian Day Numbers

open
nobody
5
2006-05-10
2003-06-09
Scott A Tovey
No

It would be nice to see HebCal updated
with julian day numbers for both Gregorian
and Herbrew Days. This would allow for
greater accuracy when it comes to days
prior to the 10 day correction by Pop Gregory.
It would also be an ideal way to correct
the assumed 0 year that does not exist
in the Gregorian calendar.

I sent an email but am posting this here
to insure that it is seen by all who are
working on this project.

Scott

Discussion

  • Danny Sadinoff
    Danny Sadinoff
    2006-05-10

    • labels: --> hebcal for Unix (C)
     
  • Danny Sadinoff
    Danny Sadinoff
    2006-05-10

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    Good idea.

     
  • Scott A Tovey
    Scott A Tovey
    2006-05-10

    • summary: Juliam Day Numbers --> Julian Day Numbers
     
  • Scott A Tovey
    Scott A Tovey
    2006-05-10

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    Some thoughts on the differences between
    the Julian and Gregorian calendars.

    I've done a lot of thinking about the differnce
    between the Julian calandar and the Gregorian
    calandar since I posted the Julian day suggestion.

    I believe that their is a misunderstanding about
    the ten day correction to the calandar that occured
    when Pope Gregory initiated the Gregorian calendar.

    When one offsets the current Gregorian calendar by
    the ten days or so that the Julian calendar is off
    you end up with the Julian calendar as opposed to
    the Gregorian Calendar.

    The Gregorian Calendar is based on a specific year
    in history that it begins as year 1 which was at
    the time thought to be the birth year of Christ.
    The Julian calendar however, is based on a specific
    year in history that is considered the founding of
    the city of Rome. Currently, the year that is observed
    in both calendars are given the same numeric value
    as though both Calendars are observing the same time
    period when in fact they are not.

    It is impossible for the Julian Calendar to be in the
    year 2006 ad or ce being that it's first year of
    observance was in 45 bc or bce by Julius Ceasar.
    Thus the Julian calendar year ought to be at the
    least 2051. When Julius Ceasar initiated the calendar
    the City of Rome was considered to be 708 years old
    and this was the counting of the Roman year. Therefore,
    to be more accurate, the Julian Calendar year ought
    to be 2759.

    I do not know when the confusion between the two
    calendars began but it was and is disingenuouse
    to consider that both calendars are one and the
    same. In this scenario, one need not consider
    the ten day difference to obtain the correct
    Gregorian date of an event. When one considers
    the day difference between the Gregorian Calendar
    and the Julian Calendar, they are actually looking
    at the Julina date of the event. This difference
    of dates of a given event becomes less and less
    until one reaches the first century when the
    difference is eliminated. Because the Julian
    Calendar has more leap years than the Gregorian
    Calendar, the two calendars must be considered
    different Calendars not one and the same.

    The mathematical equation used to determine leap
    years in the Gregorian Calendar is far more accurate
    than that of the Julian Calendar. While the Julian
    calendar was the predecessor and the template of the
    Gregorian calendar, in truth, the two calendars are
    entirely different when their leap years are considered.

    With this in mind, we can determine the Gregorian date
    of a Hebrew event based on the alignment of the Hebrew
    and Gregorian Calendars without taking into consideration
    the ten day difference between the Julian Calendar and
    the Gregorian Calendar. Furthermore, all bc dates ought
    to be considered Gregorian calendar dates not Julian
    calendar dates. This gives us an accurate Gregorian
    calendar date and Hebrew calendar date alignment
    for the bc years without the need to be concerned with
    the ten day Julian calendar date inaccuracy as we are
    focussing on the current Gregorian calendar dates and
    not the previous Julian calendar dates.

    The current calendar we use is the Gregorian calendar
    as the previous Julian calendar was proven to be
    inaccurate and flawed. Secondly, the Julian calendar
    was further corrupted by the fact that the true
    year of the calendar was changed at some point in
    the past to reflect the current Gregorian year, thereby
    eliminating it as a guide to accurate historical
    time record.

    Scott

     
  • Danny Sadinoff
    Danny Sadinoff
    2006-05-10

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    Emitting the julian day number or the (conventionally
    defined) Julian calendar date is not difficult.

    Scott, in implementing this feature, I do not intend to
    offset the year number by 54 as you describe. Julian day
    numbers are well-defined in the (astronomical) literature,
    and the Julian calendar is well-understood, as far as I can
    tell, to correpoond to the gregorian calendar of today, give
    or take a few weeks, not tens of years.

    For instance, if you were to examine a gravestone in Ireland
    or Russia from the 14th century, the dates are all "off"
    from our current Gregorian calation by weeks, not years.

    If, on the other hand, you'd like to understand dates from
    before the 8th century, that's another kettle of fish
    entirely. I firmly believe that hebcal is the wrong tool
    for this job, since it's very doubtful that the Jewish
    calendar was computable before then.

    In short, I intend to add the Julian (-10 days) calendar,
    as well as astronomical Julian day numbers to hebcal, as an
    option. It's possible that a tunable "cutover" date could
    be implemented, but I feel that a better strategy would be a
    global switch, since a "smooth" cutover likely never
    happened, anywhere.

    q.v. http://en.wikipedia.org/wiki/Gregorian_calendar#Timeline

     
  • Scott A Tovey
    Scott A Tovey
    2006-05-10

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    Sounds like a plan.

    I found out that the switch from the Roman
    AUC years to the Current BC AD year format
    was implemented in 527 by the Roman abbot
    Dionysius Exiguus. I always thought that
    it was implemented at the same time as
    the Gregorian correction. I was wrong.

    Take care.

    Scott
    >>>>
    In short, I intend to add the Julian (-10 days)
    calendar, as well as astronomical Julian day
    numbers to hebcal, as an option. It's possible
    that a tunable "cutover" date could be implemented,
    but I feel that a better strategy would be a
    global switch, since a "smooth" cutover likely
    never happened, anywhere.
    >>>>>