In Europe, an increasing interest exits on a future autonomous Space Surveillance System. Currently, the knowledge of close-Earth space situation is mainly based on information provided by the US Space Command (USSPACECOM). The design and capabilities study of a future European Space Surveillance System was analysed as a part of the Advanced Space Surveillance System Simulator (AS4) project. AS4 was conceived as an end-to-end simulator which included a full set of capabilities such as generation and propagation of realistic population, measurements generation, orbit determination, correlation and final product delivery. This paper describes the continuation of the AS4 simulator. It is mainly focused in the initial orbit determination algorithms for optical measurements that were developed and applied to define new telescopes strategies. Numerical results and analysis to evaluate accuracy are presented.