Twenty-one years of Venus risings and settings recorded under King Ammisaduqa, copied a thousand years later at Nineveh: the oldest long-run astronomical dataset on Earth, and the pivot of a century-long fight over the date of Babylon itself.
Documented
The documented dataset
Tablet 63 of the omen series Enuma Anu Enlil survives in seventh-century BC copies from Ashurbanipal's library at Kuyunjik, preserving Venus records tied to the reign of Ammisaduqa, fourth king of Babylon's first dynasty. In 1912 Franz Kugler identified the tablet's Year of the Golden Throne as Ammisaduqa's year 8, turning the record into the linchpin of Mesopotamian absolute chronology. Depending on how the Venus intervals are read, the record's start lands at 1702, 1646, 1638, 1582, or 1550 BC: the High, Middle, Low, and Ultra-Low chronologies, which shift the fall of Babylon by more than a century.
Assessment: Fully documented: the copies, the dataset, the 1912 identification, and the four-way split. Documented also is that the field's majority still rides the Middle chronology.
Stories
The horoscope under the clock
The tablet's day job was not astronomy but omen: Venus vanishes, a king falls; Venus returns, the land rejoices. The same clay holds the data and the divination, and Babylon's sky-watchers saw no seam between them. Later astrology, the personal horoscope, the planetary week, grows from this filing system where measurement and meaning were one department.
Assessment: Stories: the omen content is right there in the text. The folk reading, that the science was a byproduct of fortune-telling, inverts the tablet's own view, in which the fortune-telling was the point and the precision was the craft.
Interesting claims
The circularity charge
The methodological complaint, pressed by chronology skeptics: editors along the copy chain normalized the Venus data, so the clock was partly rebuilt by its own users, and choosing a chronology first chooses your reading of the tablet. The ultra-low proposal of Gasche, Armstrong, Cole, and Gurzadyan (Dating the Fall of Babylon, 1998) pushed Babylon's fall to 1499 BC and was largely declined by the field, leaving the Middle chronology in place by consensus rather than proof.
Assessment: Interesting: the circularity is real and admitted in the literature; so is the practical fact that the Middle chronology meshes with dendrochronology and the Assyrian lists. Filed: the clock works, but its warranty is a footnote war.
Sources and further reading
Enuma Anu Enlil tablet 63 and its 7th-century BC copies from Kuyunjik
Kugler (1912): the Year of the Golden Throne identified as Ammisaduqa year 8
the chronology split: High 1702, Middle 1646, Low 1638, Ultra-Low 1582 and 1550 BC
Gasche, Armstrong, Cole and Gurzadyan, Dating the Fall of Babylon (1998), the ultra-low proposal and its reception
Reiner and Pingree on the transmission of the Venus records
Worth asking
When the clock and the calendar must calibrate each other, which one do you trust first?