The HETDEX Instrumentation: Hobby-Eberly Telescope Wide-field Upgrade and VIRUS

Gary J. Hill, Hanshin Lee, Phillip J. Macqueen, Andreas Kelz, Niv Drory, Brian L. Vattiat, John M. Good, Jason Ramsey, Herman Kriel, Trent Peterson, D. L. Depoy, Karl Gebhardt, J. L. Marshall, Sarah E. Tuttle, Svend M. Bauer, Taylor S. Chonis, Maximilian H. Fabricius, Cynthia Froning, Marco H user, Briana L. IndahlThomas Jahn, Martin Landriau, Ron Leck, Francesco Montesano, Travis Prochaska, Jan M. Snigula, Greg Zeimann, Randy Bryant, George Damm, J. R. Fowler, Steven Janowiecki, Jerry Martin, Emily Mrozinski, Stephen Odewahn, Sergey Rostopchin, Matthew Shetrone, Renny Spencer, Erin Mentuch Cooper, Taft Armandroff, Ralf Bender, Gavin Dalton, Ulrich Hopp, Eiichiro Komatsu, Harald Nicklas, Lawrence W. Ramsey, Martin M. Roth, Donald P. Schneider, Chris Sneden, Matthias Steinmetz

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59 Scopus citations


The Hobby-Eberly Telescope (HET) Dark Energy Experiment (HETDEX) is undertaking a blind wide-field low-resolution spectroscopic survey of 540 deg2 of sky to identify and derive redshifts for a million Lyα-emitting galaxies in the redshift range 1.9 < z < 3.5. The ultimate goal is to measure the expansion rate of the universe at this epoch, to sharply constrain cosmological parameters and thus the nature of dark energy. A major multiyear Wide-Field Upgrade (WFU) of the HET was completed in 2016 that substantially increased the field of view to 22′ diameter and the pupil to 10 m, by replacing the optical corrector, tracker, and Prime Focus Instrument Package and by developing a new telescope control system. The new, wide-field HET now feeds the Visible Integral-field Replicable Unit Spectrograph (VIRUS), a new low-resolution integral-field spectrograph (LRS2), and the Habitable Zone Planet Finder, a precision near-infrared radial velocity spectrograph. VIRUS consists of 156 identical spectrographs fed by almost 35,000 fibers in 78 integral-field units arrayed at the focus of the upgraded HET. VIRUS operates in a bandpass of 3500-5500 Å with resolving power R ≃ 800. VIRUS is the first example of large-scale replication applied to instrumentation in optical astronomy to achieve spectroscopic surveys of very large areas of sky. This paper presents technical details of the HET WFU and VIRUS, as flowed down from the HETDEX science requirements, along with experience from commissioning this major telescope upgrade and the innovative instrumentation suite for HETDEX.

Original languageEnglish (US)
Article number298
JournalAstronomical Journal
Issue number6
StatePublished - Dec 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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