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29 September 2004 The Giant Magellan Telescope (GMT) structure
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A concept design has been developed for the Giant Magellan Telescope (GMT). The project is a collaboration by a group of U.S. universities and research institutions to build a 21.5-meter equivalent aperture optical-infrared telescope in Chile. The segmented primary mirror consists of seven 8.4-meter diameter borosilicate honeycomb mirrors that will be cast by the Steward Observatory Mirror Laboratory. The fast primary optics allow the use of unusually compact telescope and enclosure structures. A wide range of secondary trusses has been considered for the alt-az mount. The chosen truss employs carbon fiber and steel and, due to its unique geometry, achieves high stiffness with minimal wind area and primary obscuration. The mount incorporates hydrostatic supports and a C-ring elevation structure similar in concept to those implemented on the Magellan 6.5-m and LBT dual 8.4-m telescopes. Extensive finite element analysis has been used to optimize the telescope structure, achieving a lowest telescope resonant frequency of ~5 Hz. The design allows for removal and replacement of any of the 7 subcells for off-telescope mirror coating with no risk to the other mirrors. A wide range of instruments can be used which mount to the top or underside of a large instrument platform below the primary mirror cells. Large instruments are interchanged during the day while small and medium-sized instruments can be enabled quickly during the night. The large Gregorian instruments will incorporate astatic supports to minimize flexure and hysteresis.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steve Gunnels, Warren B. Davison, Brian Cuerden, and Edward Hertz "The Giant Magellan Telescope (GMT) structure", Proc. SPIE 5495, Astronomical Structures and Mechanisms Technology, (29 September 2004);


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