The Quest for the Cosmological Parameters

Abstract. The following review is based on lectures given in the 1 st Samos Cosmology summer school. It presents an attempt to discuss various issues of current interest in Observational Cosmology, the selection of which as well as the emphasis given, reflects my own preference and biases. After presenting some Cosmological basics, for which I was aided by excellent text-books, I emphasize on attempts to determine some of the important cosmological parameters; the Hubble constant, the curvature and total mass content of the Universe. The outcome of these very recent studies is that the concordance model, that fits the majority of observations, is that with Ωm + ΩΛ = 1, ΩΛ ≃ 0.7, H ◦ ≃ 70 km s −1 Mpc −1, ΩB ≃ 0.04 and spectral index of primordial fluctuations, the inflationary value n ≃ 1. I apologise before hand for the many important works that I have omitted and for the possible misunderstanding of those presented. 1 Background- Prerequisites The main task of Observational Cosmology is to identify which of the idealized models, that theoretical Cosmologists construct, relates to the Universe we liv