The Babylonian astronomical diaries : a contextual survey and graphical analysis of their implied reference system

Abstract

Abstract Babylonian scribes nightly observed and recorded celestial events for over six centuries during the first millennium BC. A number of cuneiform tablets containing these astronomical diaries have been recovered and later were translated by Abraham Sachs and Hermann Hunger.

The majority of diary entries track the position of the moon with reference to 31 "normal stars," all within 10 degrees of the ecliptic. Entries specify the moon as being "above," "below," "in front of," or "behind" a second body by a specified distance in cubits. The scribes fail to define either the reference system used for these topographical relations or the dimensions of a cubit. Any instruments that may have been utilized in these observations have not survived.

Gerd Graffhoff posits that "topographical relations in the Babylonian Diaries are accurately measured ecliptic coordinates," and that a cubit represents 2.5 angular degrees. His findings have been questioned and I examine the se is sues through a new approach. In my research I perform a contextual study of factors leading to the diary observations. Additionally I conduct a graphical computer analysis that depicts actual positions of the bodies in question on specified dates.

Computer-generated star-charts and coordinates for the selected entries clearly show a direct interdependence between the topographical relations and the celestial course of the sun, moon, and planets. Virtually every relation that I examined corresponds generally with celestial longitude and latitude. While my study produced certain cubit values not far from Graffhoff's, I found an inconsistency in these dimensions that casts great doubt as to the existence of a uniform system of measure. The computer-generated star-charts distinctly reflect correlation to the general path of ecliptic travel, but it is doubtful that the topographical relations of the Astronomical Diaries refer to any specific coordinate reference system.