The Giant Magellan Telescope (GMT), one of several next generation Extremely Large Telescopes (ELTs), is a 25.4 meter diameter altitude over azimuth design set to be built at the summit of Cerro Campanas at the Las Campanas Observatory in Chile. This paper provides an update and overview of the ongoing efforts for the GMT site, infrastructure, facilities and enclosure design. The paper provides insight of the proposed systems, trade studies and approach resulting in the current design solution.
The Giant Magellan Telescope (GMT), one of several next generation Extremely Large Telescopes (ELTs), is a 25.4 meter diameter altitude over azimuth design set to be built at the summit of Cerro Campánas at the Las Campánas Observatory in Chile. The paper describes the use of Building Information Modeling (BIM) for the GMT project.
The Giant Magellan Telescope (GMT) is a 25-meter optical/infrared extremely large telescope that is being built by an
international consortium of universities and research institutions. It will be located at the Las Campanas Observatory,
Chile. The GMT primary mirror consists of seven 8.4-m borosilicate honeycomb mirror segments made at the Steward
Observatory Mirror Lab (SOML). Six identical off-axis segments and one on-axis segment are arranged on a single
nearly-paraboloidal parent surface having an overall focal ratio of f/0.7. The fabrication, testing and verification
procedures required to produce the closely-matched off-axis mirror segments were developed during the production of
the first mirror. Production of the second and third off-axis segments is underway.
GMT incorporates a seven-segment Gregorian adaptive secondary to implement three modes of adaptive-optics
operation: natural-guide star AO, laser-tomography AO, and ground-layer AO. A wide-field corrector/ADC is available
for use in seeing-limited mode over a 20-arcmin diameter field of view. Up to seven instruments can be mounted
simultaneously on the telescope in a large Gregorian Instrument Rotator. Conceptual design studies were completed for
six AO and seeing-limited instruments, plus a multi-object fiber feed, and a roadmap for phased deployment of the GMT
instrument suite is being developed.
The partner institutions have made firm commitments for approximately 45% of the funds required to build the
telescope. Project Office efforts are currently focused on advancing the telescope and enclosure design in preparation for
subsystem- and system-level preliminary design reviews which are scheduled to be completed in the first half of 2013.
The GMT (Giant Magellan Telescope) is a large ground-based telescope for astronomical research at optical and infrared
wavelengths. The telescope is enclosed inside an Enclosure that rotates to follow the tracking of the telescope. The
Enclosure is equipped with adjustable shutters and vents to provide maximum ventilation for thermal control while
protecting the telescope from high wind loads, stray light, and severe weather conditions. The project will be built at Las
Campanas Observatory in Chile on Cerro Las Campanas. The first part of this paper presents the wind tunnel test data as
well as CFD (Computational Fluid Dynamics) study results for the GMT Enclosure. The wind tunnel tests include
simulations for: a) Topography, b) Open Enclosure (all the shutters and vents open), and c) Closed Enclosure (all the
vents and shutters closed). The CFD modeling was carried out for a wide range of conditions such as low and high wind
speeds at various wind directions, and for the fully open and partially open Enclosure. The second part of this paper
concerns the thermal effects of the Enclosure steel members. The wind speed and member sizes have been studied in
relation to the required time to reach a defined temperature inside the Enclosure. This is one of the key performance
characteristics of the Enclosure that can affect "Dome Seeing" significantly. The experimental data and theoretical
predications have been used to identify the areas inside the Enclosure that need to be ventilated. The Enclosure thermal
control strategy has been determined and an optimized system has been designed based on the final results.