<title>VLT primary support system</title>

A large, flexible mirror like the VLT Primary needs several sophisticated support systems, one for each operation during its lifetime. Typical mirror specifications, design loads and design requirements are given. For astronomical use ZEISS proposes a hydraulical passive support system for all 6 DOF of the mirror. For active correction an actuator with high dynamic bandwidth is connected to the axial passive support. Design features are discussed. Particularly the dynamic behavior of the support system is studied in an ACSL simulation. Active damping is foreseen as backup feature.