The GLONASS system is rapidly becoming of great interest for navigation, timing and geodetic applications, usually in combination with the GPS system. The goal of this paper is to describe the first world-wide campaign of observations of GLONASS satellites, organized with a large international participation. This first campaign, called IGEX98 will be organized in fall 1998. In this paper, we will
... [Show full abstract] focus on the scientific objectives and present the on-going preparation for this campaign. We will address several important scientific issues that could be solved in the short term by such a campaign. A large number of organizations have already answered positively to the IGEX98 International Call for Participation.