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abstract
The Hobby-Eberly Telescope (HET), currently under construction at McDonald Observatory, is a unique approach to large telescope system design. The HET, formerly called the Spectroscopic Survey Telescope before its groundbreaking in March 1994, has a number of unique features that allow it to meet its science mission with unusual cost effectiveness. This fixed altitude design has a spherical primary mirror consisting of 91 identical hexagonal segments made of low expansion glass with a total collecting area of 77.6 square meters. The pupil of the HET varies from a maximum diameter of 9 meters as an all reflecting spherical aberration corrector tracks the astronomical target on the spherical focal surface of the primary mirror. This tracking is accomplished with a multi-axis system that provides precision motions and minimal pupil obstruction. A final focal plane field of view of 4 arc minutes at f/4.7 will deliver seeing limited images at the McDonald site. A combination of a 35 degree tilt from zenith.
The HET is well suited to spectroscopic follow-up of objects from wide field ground based and space based surveys. Instrumentation planned for the HET include a low resolution imaging spectrograph in the focal plane and fiber coupled medium and high resolution instruments. The fiber feeds allow rapid switching of instruments compatible with a queue scheduled observing mode. Anticipated performance of the HET with such instruments will be present along with the current status of the project.
First light is expected in 1996.
