Calculating the end-point from a given Day of Creation
Posted by Luminakisharblaze on March 4, 2011 at 11:20am in 2012
UPDATE 15/10/02: The whole page has now been corrected, BUT THERE IS STILL A 1-DAY DISCREPANCY.
The calendrical system of the Maya was older and more complex (and accurate) than that of the Aztecs, who had forgotten the Long Count system. The Mayan "Great Cycle", or 13-Baktun cycle, which is part of the Long Count, is 1,872,000 days long, and the start date is given as August 11th 3114 BC or August 13th 3114 BC according to the 2 most popular correlations, (known as the GMT 584283 and GMT 585285 respectively). The end-date is given either as 21 December 2012 AD or 23 December 2012 AD respectively. There are many other alternative start & end-dates that I have come across since first writing this page, especially in 2011 and 2013. There is now a special 2012: Dire Gnosis article about these : End-Date Confusion Explained.
In order to work out leap-years, the rule is a leap year must be divisible by 4, unless it is divisible by 100 - then it is not a leap year - unless it is divisible by 400, in which case it is a leap-year. The exception is 1 BC which is a leap year - plus the BC years have to converted to "astronomical years" by subtracting one year, to make up for the missing year zero, before calculation.
To work out the termination point using the GMT 584283 correlation:
The "zero-day", or Day of Creation; 0.0.0.0.0 in The Long Count, is 11th August 3114 BC in Gregorian calendar. This is the same as the year -3113 in "astronomer's jargon" which inserts an extra "year zero" to make BC-AD calculations simpler. Since the Gregorian calendar didn't exist then, and has to be back-calculated, it is should be more efficient to use a Julian Day number system - in this case, JD 584283. The only trouble is, the JD starts at midday, so often leads to confusion see another special 2012: Dire Gnosis explanation on the Maya Links and calculators page.
After 0.0.0.0.0 there are 1,872,000 days until the next Day of Creation, which is 13.0.0.0.0.
We know this is 5125 years (3114 + 2012 = 5126; subtract 1 for the missing "year zero" = 5125) 3114 + 2012 - 1 = 5125
Multiply the 5125 years from 3114 BC to 2012 AD by 365, to get 1870625; 5125 x 365 = 1870625
then dividing 5125 by 4 to get the number of "simple" leap days; (=1281), 5125 / 4 = 1281
then calculating how many century years from 3114 BC to 2012 AD are NOT leap years, by the century rule above (=39);
Century Years astronomical (+ 1 to convert to Gregorian for BCE years) LEAP YEAR? (divisible by 400) Non-leap year tally
-3100 NO 1
-3000 NO 2
-2900 NO 3
-2800 YES -
-2700 NO 4
-2600 NO 5
-2500 NO 6
-2400 YES -
-2300 NO 7
-2200 NO 8
-2100 NO 9
-2000 YES -
-1900 NO 10
-1800 NO 11
-1700 NO 12
-1600 YES -
-1500 NO 13
-1400 NO 14
-1300 NO 15
-1200 YES -
-1100 NO 16
-1000 NO 17
-900 NO 18
-800 YES -
-700 NO 19
-600 NO 20
-500 NO 21
-400 YES -
-300 NO 22
-200 NO 23
-100 NO 24
0 (1BC /"year zero") YES -
100 NO 25
200 NO 26
300 NO 27
400 YES -
500 NO 28
600 NO 29
700 NO 30
800 YES -
900 NO 31
1000 NO 32
1100 NO 33
1200 YES -
1300 NO 34
1400 NO 35
1500 NO 36
1600 YES -
1700 NO 37
1800 NO 38
1900 NO 39
2000 YES -
Total
39
and subtracting that from 1281 (=1242). 1281 - 39 = 1242
Then 1242 was added to 1870625, 1242 + 1870625 = 1871867
and the result (=1871869) was subtracted from 1,872,000 – the number of days in the Great Cycle, to get 133 – the number of days left until termination of the cycle. 1872000 - 1871867 = 133
If the cycle began at dawn on August 11th 3114 BC; 5125 years & 133 days later, or 1, 872,000 days later, at the end of December 21st 2012. August 11th 2012 (inclusive) + 133 = December 21st 2012 (inclusive)
so... August 11th 3114 BC 00.00 hrs + 1,872,000 = 21st December 2012 AD 23.59 hrs
JD 584283 + 1,872,000 = JD 2456283 = midday 11/8/3114 BC - midday 21/12 2012, SO THERE IS STILL A 1-DAY DISCREPANCY!
Here is a much simpler way to work it out, from John Major Jenkins:
Anyone with a Julian Day ephemeris can make the following simple calculation. December 21, 2012 is Julian Day 2,456,283. Subtract from this the number of days in 13 baktuns (1,872,000). The result is 584283, the Julian Day number of the Long Count's zero day back in 3114 BC, thus confirming the end-date as December 21, 2012.
(Source http://www.diagnosis2012.co.uk/add.htm#add)