SpaceX. NASA Featured Images and Galleries. Hobby-Eberly Telescope. Hobby-Eberly Telescope The HET is one of the world's largest optical telescopes, with an effective aperture of 9.2 meters and a 78 square meter, hexagonal mirror array made from 91 segments.
Its design is revolutionary. It sits at a fixed elevation angle of 55º, and rotates in azimuth to access 81% of the sky visible from McDonald Observatory (discounting the "high airmass" zone right next to the horizon which telescopes normally avoid). The HET was built for approximately 15-20% of the cost of other 9 meter class telescopes.