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As it was said by one of the participants to this workshop"e; In our attempts to understand the spectral evolution of galaxies, we are fortunate indeed to have the ability to look back in time and observe galaxies as they were billions of years ago. Perhaos in no other discipline is it possible to gain such a direct view to hJstory. The galaxies we seek to study are remote, their light faint, and thus only recently has it become technicaJlv feasible to sample the spectra of normal luminosity galaxies at lookback times of five billion years or more"e; .... or, perhaps. even to see galaxies in the process of their formation. or shortly afterwards. This fourth workshop organized by the "e;Advanced School ot Astronomy was indeed centered on the "e;Spectral Evolution of Galaxies"e;. on reviewing and discussing the relevant astrophysical processes and on assessing our current ability to model and understand the evolution of stellar populations. Following an opening session dealing with some outstanding questions of galaxy evolution. Session I addressed the specific problems of galaxy and star formation processes. topics of uncertainty and controversy to which IRAS observations may give novel perspectives. The properties of stellar populations in the local group of galaxies formed the basis of Session II. Session III dealt with the fundaments of the theory of spectral and photometrical evolution of stellar populations. and with recent developments in the theory of stellar structure. a necessary step to model and understand galactic evolution.

ELlA M. LEIBOWITZ Director, Wise Observatory Chair, Scientific Organizing Committee The international symposium on "e;Astronomical Time Series"e; 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.

A star in a binary may interact with its companion and this complicates significantly its structure and evolution. During several decades in the past many astronomers hoped that the number of binaries is small. This is sometimes reflected in theoretical studies dealing with large populations of stars where it is ASSUMED (without any justification) that binaries do not alter the results. The number of confirmed binaries increases as observations improve and we there­ fore thought that the time was right to organize a meeting where the main topic would be the effect of binaries on stellar population studies. The SOC proposed a program with extended general overviews and highlights of non-evolved and evolved binaries, with low mass, intermediate mass and massive components, the link with supernova explosions, pulsars and gamma-ray bursts, the effect of binaries on the chemical evo­ lution of galaxies. Specialists in the different research fields were invited and have given very interesting and highly educational talks. As can be noticed by reading the proceedings, the authors have put a lot of effort in preparing their contribution.