Subject: corrective measures

From: Rives McDow <[email-masked]>
Date: Mon, 07 Feb 2000 08:58:05 -0800

Earlier I made a post that was misinterpreted.  Here is a correcting bit.

    I wasn't proposing to convert to the Julian Calendar, but to the julian
day count.  This use of a name that is so similar to an existing calendar
system has caused a lot of confusion, but there is no relationship at all
between the two methods.  The julian day count was proposed by the
astronomer Scallinger in some former century, after running into problems
converting back and forth between ancient calendar systems to pin down
astronomical events.   Scallinger picked a calendrical conjunction that
predated all the calendar systems in history with the exception, I believe
of the Mayan calendar.  This date was Gregorian 4713 BC Jan. 1, I believe.
I am travelling right now, and my references are at home, along with all my
source and header files.  Today is julian Day 2451581, or 2451582.1717 right
now to be exact, as the day is usually expressed as a float referenced to
Greenwich.  The modified julian date, used by Nasa and others not wanting or
having space for such a large number in their memory map or processor
capabilities, is the julian day minus 2,400,000.  Today's modified julian
day is 51581.  Either works, as the other can be derived by simple
subtraction or addition.  Here is a url that has a pretty good overview of
today's date in various calendar systems.

http://www.ecben.net/calendar.shtml

   This can seem a little overwhelming when first considering the coding.
However, I have found that calendar systems are solar, lunar, or
solar/lunar, and that the differences are primarily the setting of the
epoch, with a few exceptions (Hebrew being one).  Converting back and forth
between the julian day count and any calendar system is fairly
straightforward, using the proper algorithm.  I reference the julian day
count to the west side of the International Date Line, for reasons stated
earlier.  This has proved to be the best approach in the applications I have
developed so far, but I am open to arguments.

Sincerely,

Rives McDow