The Hobby-Eberly Telescope (HET) is a large optical telescope located at the McDonald Observatory in Texas, USA. It is one of the largest telescopes in the world, with a segmented mirror that has an effective diameter of 10 meters. Its innovative design and relatively low cost compared to other telescopes of similar size are due to its specialization in spectroscopy, allowing for the detailed observation of celestial objects by breaking down light into its components.

Unlike conventional telescopes, the HET does not fully move on both the altitude and azimuth axes to track objects in the sky. Instead, it remains fixed at a 35-degree angle, using a secondary mirror system and a movable platform to adjust the field of view, enabling it to follow objects over a limited section of the sky. This approach significantly reduces construction and operational costs without sacrificing its ability to study astronomical phenomena with precision.

The HET has been used in pioneering research, including the search for exoplanets, studies on the expansion of the universe, and detailed analysis of galaxy structure. One key project that has leveraged its capabilities is the HETDEX (Hobby-Eberly Telescope Dark Energy Experiment), aimed at investigating dark energy and its role in the accelerated expansion of the cosmos.

The construction and operation of the HET have been made possible through collaboration between U.S. universities, such as the University of Texas at Austin, and international institutions. This partnership has enabled the HET to remain at the forefront of global astronomical research, with results that have made a significant impact on the field of cosmology.