Babylonian (AST)
| Epoch | Confidence | Associated with |
|---|---|---|
| 29 March 310 BCE +15:00:00 | Medium | Babylon |
Overview
The Babylonian calendar is an observational lunisolar calendar that was used in ancient Babylon. It consists of 12 months of 29 or 30 days that begin after the first sighting of the new crescent moon at sunset. An intercalary month is added every 2-3 years in accordance with the 19-year Metonic cycle, typically repeating the 12th month but repeating the 6th month for only the 17th year of the Metonic cycle.
Days start at sunset. While there is no week structure, "holy-days" take place at intervals of 7 days after the start of each month to make offerings to specific gods; Marduk and Ishtar on the 7th, Ninlil and Nergal on the 14th, Sin and Shamash on the 21st, and Enki and Mah on the 28th.
Due to the long history of empires and conquests of Babylon, years can be counted from a number of different epochs. Two are displayed here: the Seleucid Era (SE) denoting the time since the founding of the Seleucid Empire, and the Asarcid Era (AE) denoting the time from the start of the Arsacid Empire.
Info
The Babylonian calendar is derived from the ancient Sumerian calendar and shares many similarities in month names, while the Hebrew calendar is derived from the Babylonian calendar.
| Months | |||
|---|---|---|---|
| Month | Cuneiform | Transliteration (Akkadian) | Approx. Gregorian |
| 1 | ๐๐ | Arah Nisฤnu | Mar/Apr |
| 2 | ๐๐ | Arah ฤru | Apr/May |
| 3 | ๐๐ | Arah Simฤnu | May/Jun |
| 4 | ๐๐ | Arah Dumuzu | Jun/Jul |
| 5 | ๐๐ | Arah Abu | Jul/Aug |
| 6 | ๐๐ฅ | Arah Ulลซlu | Aug/Sep |
| Intercalary (year 17 only) | ๐๐๐๐ฅ | Arah Makarลซลกa Ulลซlu | Sep |
| 7 | ๐๐ฏ | Arah Tiลกrฤซtum | Sep/Oct |
| 8 | ๐๐ณ | Arah Samnu | Oct/Nov |
| 9 | ๐๐ถ | Arah Kislฤซmu | Nov/Dec |
| 10 | ๐๐ | Arah แนฌebฤtum | Dec/Jan |
| 11 | ๐๐ฉ | Arah ล abฤแนญu | Jan/Feb |
| 12 | ๐๐บ | Arah Addaru / Adฤr | Feb/Mar |
| Intercalary | ๐๐๐๐บ | Arah Makarลซลกa Addari / Arah Addaru Arku | Mar |
| Holy-days | |
|---|---|
| Day | Offering to |
| 7 | Marduk and Ishtar |
| 14 | Ninlil and Nergal |
| 21 | Sin and Shamash |
| 28 | Enki and Mah |
Accuracy
The Babylonian calendar is well-documented, but there is some debate as to how it should be calibrated. Certain dates are well-defined, but since it is largely an observational calendar, then there is no set formula to determine the start of each month. This site uses 6pm in Babylon as the time of sunset, and the start of a month is calculated as being the first sunset that occurs at least 24 hours after a new moon.
The dates that result from this calculation line up very closely with date tables found from various sources, but not exactly. They also vary amongst each other. It is unclear how these tables were calculated, so it's possible that any or all of these calculations are wrong in some way.
The Metonic cycle wasn't established in the Babylonian calendar until around 380 BCE. Leap years prior to that date aren't handled with historical accuracy. Similarly, dates after 75 CE are calculated but not historical.
The intercalary month of ๐๐๐๐ฅ was not explicitely named but directly described. The name was chosen to match the pattern found in the other intercalary month, ๐๐๐๐บ.
Source
Much of the information on this calendar came from its Wikipedia article.
The calendar can be calibrated using this converter which is sourced from this table of dates.