The GMT-Consortium Large Earth Finder (G-CLEF): An optical Echelle spectrograph for the Giant Magellan Telescope (GMT)

Andrew Szentgyorgyi, Daniel Baldwin, Stuart Barnes, Jacob Bean, Sagi Ben-Ami, Patricia Brennan, Jamie Budynkiewicz, Moo Young Chun, Charlie Conroy, Jeffrey D. Crane, Harland Epps, Ian Evans, Janet Evans, Jeff Foster, Anna Frebel, Thomas Gauron, Dani Guzmán, Tyson Hare, Bi Ho Jang, Jeong Gyun JangAndres Jordan, Jihun Kim, Kang Miin Kim, Claudia Mendes Mendes De Oliveira, Mercedes Lopez-Morales, Kenneth McCracken, Stuart McMuldroch, Joseph Miller, Mark Mueller, Jae Sok Oh, Cem Onyuksel, Mark Ordway, Byeong Gon Park, Chan Park, Sung Joon Park, Charles Paxson, David Phillips, David Plummer, William Podgorski, Andreas Seifahrt, Daniel Stark, Joao Steiner, Alan Uomoto, Ronald Walsworth, Young Sam Yu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

41 Scopus citations


The GMT-Consortium Large Earth Finder (G-CLEF) will be a cross-dispersed, optical band echelle spectrograph to be delivered as the first light scientific instrument for the Giant Magellan Telescope (GMT) in 2022. G-CLEF is vacuum enclosed and fiber-fed to enable precision radial velocity (PRV) measurements, especially for the detection and characterization of low-mass exoplanets orbiting solar-type stars. The passband of G-CLEF is broad, extending from 3500Å to 9500Å. This passband provides good sensitivity at blue wavelengths for stellar abundance studies and deep red response for observations of high-redshift phenomena. The design of G-CLEF incorporates several novel technical innovations. We give an overview of the innovative features of the current design. G-CLEF will be the first PRV spectrograph to have a composite optical bench so as to exploit that material's extremely low coefficient of thermal expansion, high in-plane thermal conductivity and high stiffness-to-mass ratio. The spectrograph camera subsystem is divided into a red and a blue channel, split by a dichroic, so there are two independent refractive spectrograph cameras. The control system software is being developed in model-driven software context that has been adopted globally by the GMT. G-CLEF has been conceived and designed within a strict systems engineering framework. As a part of this process, we have developed a analytical toolset to assess the predicted performance of G-CLEF as it has evolved through design phases.

Original languageEnglish
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy VI
EditorsLuc Simard, Christopher J. Evans, Hideki Takami
ISBN (Electronic)9781510601956
StatePublished - 2016
Externally publishedYes
EventGround-Based and Airborne Instrumentation for Astronomy VI - Edinburgh, United Kingdom
Duration: 26 Jun 201630 Jun 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGround-Based and Airborne Instrumentation for Astronomy VI
Country/TerritoryUnited Kingdom


  • ELTs
  • Echelle spectrograph
  • G-CLEF
  • GMT
  • High dispersion spectroscopy
  • Precision radial velocity


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