The Babylonian astronomical diaries are a collection of Babylonian cuneiform texts which contain systematic records of astronomical observations and political events, as well as predictions based on astronomical observations. They also include other information, such as commodity prices for particular dates and weather reports.
Currently they are stored in the British Museum.
It is suggested that the Diaries were used as sources for the Babylonian Chronicles.
The Babylonians were the first to recognize that astronomical phenomena are periodic and apply mathematics to their predictions. The oldest known significant astronomical text is Tablet 63 of the Enûma Anu Enlil collection, the Venus tablet of Ammisaduqa, which lists the first and last visible risings of Venus over a period of about 21 years. It is the earliest evidence that planetary phenomena were recognized as periodic.
The systematic records of ominous phenomena in astronomical diaries began during the reign of Nabonassar (747–734 BC), when a significant increase in the quality and frequency of astronomical observations occurred. This allowed for the discovery of a repeating 18-year Saros cycle of lunar eclipses, for example.
Translations of the Diaries are published in multivolume Astronomical Diaries and Related Texts from Babylonia, edited by Abraham Sachs and Hermann Hunger.