The Grand Spherical Telescope Array (GSTA)

This paper describes a telescope concept that has an aperture area equivalent to 88 m in diameter by arranging 16 telescopes with an aperture of 22m closely within a 250m range. The primary mirror uses an off-axis spherical mirror fixed on the ground to eliminate diurnal movement and reduce costs, and a subsequent correction unit consisting of three or more aspherical mirrors corrects most of the aberrations of the primary mirror. The correction unit is placed on a cliff of about 40m high, and diurnal motion can be tracked for 20 minutes around the meridian passes. Multiple correction units separated in the north-south direction can be operated simultaneously at each telescope. The wide-field camera is integrated with the correction unit, but the other instruments are fixed on the cliff and the light is relayed there. All telescopes are equipped with wide-field cameras and enable high-speed deep surveys. High signal-to-noise ratio spectroscopic observations can be made by installing the same spectrograph on all telescopes. In addition, all telescopes have laser-guide star adaptive optics, optical delaylines, and coude paths, which allow light from all telescopes to be focused in one location in phase to function as one ultimate telescope. This will enable the exploration of exoplanets and the study of galactic objects with high angular resolution and high sensitivity.