Prototyping activities during the development of the GMT mount

The Giant Magellan Telescope (GMT) will be a 25-meter optical telescope with a maximum weight of about 2300 t, located on Cerro Las Campanas in Chile. To fulfill the challenging pointing and tracking accuracy requirements, as well as the functionality requirements of the auxiliary subsystems, complex design solutions needed to be developed. To support and validate the design of those subsystems and to provide reliable data and parameter for performance analysis, a variety of prototyping tests have been performed during the design phase. The telescope support consists of a radial spring system that allows thermal decoupling to the concrete foundation, an earthquake damping system as well as frictionless hydrostatic bearings and a high-performance direct drives and control system. Highly accurate and precise mechanical components need to be consistent to gravity-caused structural deformations. This requires special supports to avoid structural overload. These unique supports, especially developed for the GMT have been prototyped. Self-induced vibrations are one of the most disturbing influences on such complex control systems as well as the adaptive optics of the telescope and need to be suppressed or at least reduced wherever possible. Tests have been performed to measure and optimize vibration sources like cable wraps and electronic cabinets. The covers of the primary mirrors with a diameter of more than eight meters were developed and tested in full scale to ensure proper function even in tilted position when the telescope rotates in elevation. Falling object tests have been made to demonstrate the protection of the mirrors. An inflatable wash seal around each mirror has been tested to ensure reliable functionality. The presentation will provide an overview on the subsystem development test activities and show test setups and results of main component tests supporting the subsystems design and analyses.