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Hobby-Eberly Telescope at McDonald Observatory October 28, 2006.

The Hobby-Eberly Telescope is a 9.9 m telescope located at the McDonald Observatory (30.681° N 104.015° W). The telescope is named for former Texas Lieutenant-Governor Bill Hobby and for Robert E. Eberly, a Penn State benefactor. The primary mirror consists of 91 hexagonal elements. The telescope is fixed in altitude and can be moved in azimuth. It is able to observe objects for periods of 1-2 hours by the use of a tracker at its focus. The tracker follows the object across the pupil, compensating for the Earth's rotation.

Three instruments are available to analyze the light from the targets. All three instruments are spectrographs. The instruments work at high-, medium- and low-spectral resolution. The low-resolution spectrograph is housed at the prime focus, while the medium- and high-resolution spectrographs reside in the basement and the light is fed into them via a fiber-optic cable.

The telescope has been used for a wide variety of studies from our Solar System to stars in our Galaxy and studies of other galaxies. Measuring radial velocities as precisely as 1 m/s, the telescope has been used successfully to find planets orbiting around other stars. Using the low-resolution spectrograph, the telescope has been used to identify Type Ia supernovae to measure the acceleration of the Universe. The telescope has also been used to measure the rotation of individual galaxies.

The Hobby-Eberly Telescope is operated by The University of Texas McDonald Observatory for a consortium of institutions which includes The University of Texas at Austin, Pennsylvania State University, Stanford University, Ludwig Maximilians University of Munich, and Georg August University of Göttingen.

• HET General Information Page

• List of largest optical reflecting telescopes
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