This volume presents an edition of cuneiform tablets with lunar and
planetary data from the 3rd century to the 1st century B.C. Most of
these data are observations, in all likelihood excerpted from
Astronomical Diaries of the kind published in Vols. I to III. Planetary
phenomena reoccur after a certain number of years on almost the same
calendar date within the Babylonian year. The number of years is quite
easy to calculate if one has observations of planetary phenomena such as
those in the Diaries; this period is different for each planet. The
so-called goal-year texts collect observations one period earlier than
the year for which the text is intended. This enables quite good
predictions of the planet positions on particular calendar dates. The
texts were probably also used by Babylonian astronomers to investigate
periodically recurring phenomena, in order to discover means of
computing them in advance.