Top 5 Optical Telescopes By: Kiana Gathers and Mary Beth Garrett

W.M Keck Observatory  Located in Mauna Kea, Hawaii  Two telescopes: Keck 1 and Keck 2  Expected to see much farther than we can see today and help to discover how the universe began (later proved to exceed expectations)  Largest and most scientifically productive telescopes  Operates twin 10-meter optical/infrared telescopes  primary mirrors are 10 meters in diameter and are each composed of 36 hexagonal segments that work in concert as a single piece of reflective glass  Both telescopes have laser guide star adaptive optics  Confirmed 41 of the exo-planets discovered by Kepler and determined the masses of 16  Obtained the first-ever spatially resolved images of a DLA galaxy

Gran Telescopio de Canarias  Located on La Palma  Allowed the study of the nature of black holes, the formation history of stars and galaxies in the early universe, the physics of distant planets around other stars, and the nature of dark matter and dark energy in the universe  Primary mirror consists of 36 individual hexagonal segments that together act as a single mirror  Allows rotational movements of the telescope along a horizontal and vertical axis. This movement has to be extremely precise in order to keep the stars projected stably onto the detector  Discovered the whirlpool galaxy M51 and the Eskimo Nebula

Large Binocular Telescope  Located on 10,700-foot Mount Graham in the Pinaleno Mountains of southeastern Arizona  The telescope design has two 8.4-meter (28 ft) mirrors mounted on a common base  Discovered a galaxy cluster 2XMM J which was over 7 billion light years away from Earth.  Detected a 26th magnitude afterglow from the gamma ray burst GRB

Southern African Large Telescope  Located in Sutherland, South Africa  Designed mainly for spectroscopy  Design comes from the HET  It enables imaging, spectroscopic, and polarimetric analysis of the radiation from astronomical objects out of reach of northern hemisphere telescopes  Primary mirror is composed of an array of mirrors designed to act as a single larger mirror  The mirror is made up of 91 identical hexagonal segments  Is fixed at an elevation angle of 55° and moves only in azimuth;  Confirmed evidence for a very strange new planetary system, where two giant planets are orbiting a close pair of "suns"

Hobby-Eberly Telescope  Located in Mount Locke, West Texas on the Davis Mountains  Designed specifically for spectroscopy, the decoding of light from stars and galaxies to study their properties  Composed of 91 hexagonal mirror segments which must be aligned to form a perfect reflecting surface  Is fixed at an elevation angle of 55° and moves only in azimuth  Diameter is 11 meters  The mushroom-shaped tower to the side of the HET dome contains a laser-alignment system that works to keep the segments in proper alignment  Discovered three planets -- each orbiting its own giant, dying star