The day of the week has been stable across the entire era. Validation that the calculations are done correctly rests in part on finding events that fell on known days. A good example is the ancient fall of Jerusalem.
The left most item in all calendar reports is the day of the week. This was established empirically from the day of the week on current calendars. It is defined on the typical 7 day cycle and runs for all such periods across the entire system. No interruptions or changes anywhere.
Confirmation that the entire calendar system is correct can be found by looking at the date of the fall of the city of Jerusalem. The following is the relavant date:
|Fall of Jerusalem|
|Sat||10409/4/9 AA||7 Jul -579 NS||8 Mai 159 AUC||AAN: 3796929|
|909/4/9 FE||13 Jul -579 OS||8 Mai 595 BC||JDN: 1509772|
Here we see the date that Jerusalem fell to the Babylonians. It was recorded as being on the 9th day of the 4th month of Zedekiah’s 11th year, or 10409 AA 1 2 This turns out to be a Saturday, or Jewish Sabbath. The Bible does not record that this was a Sabbath, but Jerusalem has traditionally fell on Sabbath days, which is confirmed through this excercise.