Design and analysis of 20 m track mounted and 30 m telescopes

This paper presents designs of compact 21 and 30 m aperture telescopes with primary focal off/0.7 and f/0.56. The 20 20 telescope moves on three axes; the elevation axis (which is below the primary vertex), the azimuth axis, and a tracking axis at the center of 100 m diameter tracks. The 30 m telescope has an elevation and azimuth axis. All of the axes move on hydrostatic bearings. A primary requirement for such large telescopes is stiffness against deformation by wind gusts. The mass and stiffness needed for the structure is substantially independent of the primary mirror mass, which can therefore be set by thermal and diffraction issues. For the 21 m design, whose primary has seven 8.4 m glass segments weighing 128 tons, the total moving mass is 905 tons, and the lowest resonant frequency 6.5 Hz. For the 30 m design, whose primary has, 13 whole and 6 half, glass segments 8.7 m, across the points, weighing 256 tons, the total moving mass is 3,460 tons, and the lowest resonant frequency 5.3 Hz. These practical designs offer two versatile telescopes with high performance.