The pioneers of calculations, our beloved Assyrian ancestors, established sciences e.g., astronomy, but I found it insulting for the modern Assyrians to have an absolutely wrong Assyrian calendar hanging on their walls. I always believe simple things shall last forever, but simplicity has a limit and it shall never compromise the dignity of a matter or an object. Today, the problem is some have chosen simplicity, ease, and compromise over the valuable heritage, thus therefore, the dignity of their nation.
What we hang on our walls in views of our kids is not an Assyrian calendar; it is a “translated” version of the Gregorian calendar to the Assyrian language. If the Gregorian month has 30 days, corresponding Assyrian month has 30 days, if the Gregorian month has 29, the Assyrian month has 29 days, and so on an so forth. No sense of respect and preservation to the roots of all calendars, the Assyrian calendar, is being seen here.
Have you ever asked yourself if March 21st is the beginning of the Assyrian new year, then why 10 days later is marked to be the 1st of Nisan? What happens to those 10 days in between? Do they belong to Nisan? Because I don’t know, after all we just passed the 1st of Nisan, but if it is so, why don’t we tag them as days belonging to the month of Nisan? Look at your calendar. Mark March 21st as the “Rish Nisanu”, then try to continue counting, now naturally March 22nd, supposedly, is the 2nd of Nisan, and March 23 is the 3rd, but no, with the fallacious calendar, April 1st is the 1st of Nisan, and April 2nd is the second day, and so on. This mess continues to the edges of infinity.
We all know a year is 365.2422 days long. It takes this time for earth to orbit its sun. Western nations use 365 days in their calendar dropping the .25 = (1/4 day) remaining time. After four years, 4 times of this .2422 is equivalent to one day (1/4 day X 4) = 4/4 day = 1
In the Gregorian calendar, they add this one day to the end of the 4th year, and they call it leap year, which presents the year as having 366 days. Here is when month of February gets 29 days instead of the usual 28 days period. Last time this happened was in the year 2008 which was the leap year and the next one is going to be 2012.
(Jan:31, Feb:28, Mar:31, April:30, May:31, Jun:30, Jul:31, Aug:31, Sep:30, Oct:31, Nov: 30, Dec: 31) = 365 days
Now, some other nations handle this remaining time differently. For example, Iranians in their modern lunisolar calendar have 6 first months counted as 31 days (6 x 31 = 186) plus 5 months of 30 days (5 x 30 = 150) plus 29 days for the 12th month.
(Farvardin:31, Ordibehesht:31, Khordad:31, Tir:31, Mordar:31, Shahrivar:31, Mehr:30, Aban:30, Azar:30, Dei:30, Bahman:30, Esfand: 29) = 365 days
On the 4th year (leap year), Iranians add one day to their last month and like Gregorian, they make a year with 366 days.
Ancient Assyrians used three different algorithms to calculate the days in a year. These are:
- Lunar (<365 days): Based on the cycles of the moon. It had 12 months containing of 28, 29, or 30 days, and each two to three years, they had to add a month (13th) to their calendar to balance the dates with the seasons.
“The reason for this is that a year is not evenly divisible by an exact number of lunations, so without the addition of intercalary months the seasons would drift each year. This results in a thirteen-month year every two or three years.” 
- 2- Lunisolar (364 days): Some sort of lunisolar year days, with 12 to 13 months, but having months of 29, 30, or 31 days totaling in 364 days. Not much information found on this method. 
- 3- Schematic year of 360 days (360 + 5 = 365 days): The year starts with Spring Equinox, has 12 months of 30 days which make up a total of 360 days. Later on Assyrians had to alter and add 5 still unknown days to their calendar to balance with actual 365. 
Ancient Mayans, independently from the Assyrians, but mysteriously, have used the same 360 days year calendar as Assyrians did. They also had to add 5 additional days later on. What has happened? Why they chose 360? Didn’t they know it takes the world 365.2422 days not 360 to travel around the sun? The answer is yes they knew it. They were able and they solved much more difficult calculations. Nobody really knows why, but perhaps, the reason is at the time they started establishing their calendars, world was going around the sun in 360 days, but then something changed. 
For the secular reader, a good example for that change was published recently by NASA in which they annouced, "The Feb. 27 magnitude 8.8 earthquake in Chile may have shortened the length of each Earth day." 
And for a believer reader, The Bible specifically mentions that God has done an alteration on time. These additional 5.2422 days are God‘s Doing, and it is to be remembered among us. 
"Behold, I will bring the shadow on the sundial of Ahaz ten degrees backward." (Isaiah 38:8) & (2 Kings 20:1-11)
Both Assyrian and Mayans used base 60 in mathematics. Every clock around the world today is based on base 60. The number 60 was a sacred number in Assyria. The 360 refers to perfection (Kameeloota).
“360’s divisors are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180 and 360. (A total of 24 divisors.)
360 makes a highly composite number. Not only is 360 highly composite, but also no number less than twice as much has more divisors. 360 is also a superior highly composite number and a colossally abundant number. 360 is the smallest number divisible by every number from 1 to 10 except 7. A circle is divided into 360 degrees for the purpose of angular measurement.”
The Assyrian date function, which has been added to the Assyrian Calendar page is based on the original Assyrian 360 days calendar. The date is being calculated to the accuracy of seconds based on the exact Spring Equinox provided by the U.S. Naval Oceanography portal which is the single data access point for all public facing Meteorology and Oceanography products and services in accordance with Department of Defense (DoD) and Navy guidance.
The 12 x 30 days months will restore to life the sacred 360 days calendar once again in Assyrian history. And 5 bonus days could always be considered as holidays at the end of the Assyrian year for those of us hardworkers.
Months: (Nisannu:30, Iyaru (Yaar):30, Simanu (Khzeeran):30, Tamuzu:30, Abu (Tabbakh):30, Ululu (Elul):30, Tashritu (Tishrin I):30, Arahsamnu (Tishrin II):30, Kissilimu (Kanoon I):30, Tebetu (Kanoon II):30, Shabatu:30, Addaru:30) = 360
Limitation: Because the algorithm is based on Spring Equinox, and the only data available at the moment is for years 2000 to 2020, the function will work until 2020 when it would need new Spring Equinox to be entered into the system.
Time: Greenwich Mean Time (GMT)
What would the function show for those 5 days?
Currently it will show “Intercalation day D, [YYYY]” where D is for number of day and YYYY is for 4 digit year number until we find out what Assyrians called those 5 days.
On the March 20th, Assyrians will celebrate their new year 6760. The new year is called "Rish Nissanu" in Assyrian. Happy New Year Assyria!
- Babylonian calendar: en.wikipedia.org/wiki/Babylonian_calendar
- Assyrian calendar: en.wikipedia.org/wiki/Assyrian_calendar
- Bible Prophecy Year of 360 Days: 360calendar.com/bible-prophecy-360-days-calendar-2a.htm
- Making 360 Days in a Year: users.hartwick.edu/hartleyc/yeardays.htm
- Chilean Quake May Have Shortened Earth Days: nasa.gov/topics/earth/features/earth-20100301.html
- 360 vs. 365: direct.ca/trinity/360vs365.html
Assyrian Circular Astrolabe Reconstruction
Mesopotamian Cosmic Geography
Author: Wayne Horowitz