ELlA M. LEIBOWITZ Director, Wise Observatory Chair, Scientific Organizing Committee The international symposium on "Astronomical Time Series" was held at the Tel Aviv University campus in Tel Aviv, from December 30 1996 to January 11997. It was organized in order to celebrate the 25th anniversary of the Florence and George Wise Observatory (WO) operated by Tel Aviv University. The site of the 1 meter telescope of the observatory is near the town of Mitzpe-Ramon, some 220 km south of Tel Aviv, at the center of the Israeli Negev highland. There were two major reasons for the choice of Time Series as the sub­ ject matter for our symposium. One is mainly concerned with the subject matter itself, and one is related particularly to the Wise Observatory. There is hardly any doubt that astronomical time series are among the most ancient concepts in human civilization and culture. One can even say that astronomical time series preceeded astronomy itself, as the impression of the day /night cycle on Earth is probably the first and most fundamental effect that impress a. human being, or, in fact, most living creatures on this planet. An echo of this idea. can be heard in the Biblical story of Creation, where the concept of night and day preceeds the creation of the astronomical objects.