The Astronomical Diaries (ADs) are a set of cuneiform tablets recording a variety of observed celestial, climatic, ecological, and economic phenomena, as well as giving accounts of historical events. They constitute one of the largest collections of observational data available from the Ancient World, consisting of more than 1,000 tablets and fragments dating from ca. 650-60 BCE. The texts are being published in an ongoing endeavor since the 1980s.
The ADs are a unique example of data gathering for the purpose of establishing an empirical basis for both astronomical and astrological prediction. The better part of the information contained usually relates to celestial – astronomical and meteorological – observations, and in particular to the position of the moon in the ecliptic during each night of a Babylonian lunar month. However, it has to be emphasized that the somewhat misleading term 'Astronomical Diaries' is the modern designation by their later editor A. Sachs, who was mainly interested in the astronomical content of the tablets. The more neutral Babylonian designation was nasāru ša ginê, meaning "regular observation". The astronomical section is usually followed by price quotations for foodstuffs and wool, and a note on the level of the river Euphrates. Often, a historical section is added. The ADs are indeed the single most important source for the political history of Late Achaemenid and Seleucid Babylonia. Among the historical accounts, the quite extensive report of the battle of Gaugamela and Alexander the Great's subsequent entry into the city of Babylon has attracted particular attention (AD -330A+B), as has the description of preparatory measures preceding the First Syrian War between the Ptolemaic and the Seleucid Empires in 274/3 BCE (AD -273B).
This corpus, the largest coherent body of empirical data gathered in antiquity, is unique, and its importance can hardly be overrated. Available on Oracc are currently ADART volumes I - III. Publication of further volumes in in progress.