The Giant Magellan Telescope (GMT) is 25 meter diameter extremely large ground based infrared/optical telescope
being built by an international consortium of universities and research institutions. It will be located at the Las
Campanas Observatory in Chile. The GMT primary mirror consists of seven 8.4 meter diameter borosilicate mirror
segments. Two seven segment Gregorian secondary mirror systems will be built; an Adaptive Secondary Mirror (ASM)
to support adaptive optics modes and a Fast-steering Secondary Mirror (FSM) with monolithic segments to support
natural seeing modes when the ASM is being serviced.
Wind excitation results in static deformation and vibration in the telescope structure that affects alignment and image
jitter performance. The telescope mount will reject static and lower frequency windshake, while each of the Faststeering
Secondary Mirror (FSM) segments will be used to compensate for the higher frequency wind-shake, up to 20
Hz. Using a finite element model of the GMT, along with CFD modeling of the wind loading on the telescope structure,
wind excitation scenarios were created to study the performance of the FSM and telescope against wind-induced jitter.
A description of the models, methodology and results of the analyses are presented.
The preliminary design of the 25 m Giant Magellan Telescope (GMT) has been completed. This paper describes the design of the optics, structure and mechanisms, together with the rationales that lead to the current design. Analyses that were conducted to verify structure and optical performance are summarized. Science instruments will be mounted within the telescope structure. A common instrument de-rotator is provided to compensate for field rotation caused by the alt-az tracking of the telescope. The various instrument stations and provisions for mounting instruments are described. Post-PDR development plans for the telescope are presented.