Hobby-Eberly Telescope Dark Energy Experiment

Short Description:

HETDEX is a major experiment to search for dark energy. It uses one of the currently largest optical telescopes - the Hobby-Eberly Telescope at McDonald Observatory - and 156 separate spectrographs to map the three-dimensional positions of one million galaxies.

During five years of observations, HETDEX will collect data from galaxies whose light has travelled for 11 billion years before reaching us, yielding a detailed map of their locations. This map will allow HETDEX astronomers to measure how fast the universe was expanding at different times in its history. Changes in the expansion rate can test what role dark energy may have played at different epochs. Various explanations for dark energy and its alternatives predict different changes in the expansion rate, so by providing exact measurements of the expansion, the HETDEX map will eliminate some of the competing ideas.

Project Type:

Instrument and observing program for ground-based telescope

MPE Participation:

Member of the collaboration


Data-gathering operations have begun, with the survey completion expected in 2023


HETDEX pages at the University of Texas

Optical and Interpretative Astronomy (web pages of the MPE department involved in the project)

Hobby-Eberly Telescope
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