Prof. Dr. phil. nat. Michael Soffel is the director of the Lohrmann Observatory of the Technical University Dresden. He is an internationally known expert in relativistic celestial mechanics, relativistic astronomy and geodesy and experimental gravity research. He is the author of the books Relativity in Astrometry, Celestial Mechanics and Geodesy (Springer, 1989) and Space-Time Reference Systems. Prof. Wen-Biao Han, who receicved his Ph.D. in 2009, is full professor at Shanghai Astronomical Observatory, Chinese Academy of Sciences. His research area focuses on relativistic fundamental astronomy, numerical simulations of gravity waves and low-frequency gravitational astronomy. He is author of many scientific papers and principle investigator of the group 'Gravitational waves and relativistic fundamental astronomy' at Shanghai Astronomical observatory.