Enclosure azimuth rotation system analysis of alternatives for the Giant Magellan Telescope

Telescope enclosure azimuth rotation systems have traditionally been supported by custom bogies with steel wheels and steel rails, with mixed results in terms of long-term reliability and performance. Because the enclosure azimuth rotation mechanisms are vital for the operational success of all telescopes, and because the scale of the Giant Magellan Telescope (GMT) enclosure will exceed that of all enclosures now in existence, the GMT project team has explored alternative solutions for enclosure rotation in search of cost, reliability, and maintainability benefits. Four concepts are studied: railway bogies, ring crane bogies, segmented slewing bearings, and THK curved linear bearings. All four concepts are highly developed systems engineered to meet specific design objectives and performance requirements, some objectives of which overlap those of the GMT enclosure azimuth rotation system; however, in all four instances, significant customization or development of an altogether new product would be required for fulfilment of the GMT performance requirements.