Title: AStrometric SAtellite TRAcking Network [ASSATRAN] 

　　Speaker: Mario Gai (Turin astronomical observatory, Italy) 

　　Time & Place: Wednesday, 2:30pm, March 5th, 3rd floor middle conference room 

　　Abstract: 

　　A novel concept for large angle, high precision astrometry from ground is proposed. The goal is verification in selected areas, and future maintenance, of the Gaia catalogue precision. 

　　The concept is based on combined observation of geostationary satellites and other near-Earth space objects from two or more telescopes, applying the triangulation principle over widely separated regions of the sky. 

　　We discuss the feasibility of the technique, some of the implementation aspects, and the limitations imposed by atmospheric turbulence. 

　　The potential astrometric benefits are presented, depending on the number and position of the contributing telescopes. Long term precision on star positions and parallaxes in the few ten micro-arcsec range appears to be feasible, whereas proper motion performance may reach the few micro-arcsec range. 

　　A side advantage of the technique is the improvement on the knowledge of satellite orbits, relevant to non-astronomical applications, e.g. satellite orbit control and navigation systems.