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Large Earth Finder

Giant Magellan Telescope Consortium Large Earth Finder (G-CLEF)
The Large Earth Finder will measure the masses of Earth-like planets outside of our solar system and search for biosignatures, such as oxygen, in their atmospheres. Other specialties include characterizing quasars and the most metal poor stars, such as the [Fe/H]<–7.1 star SMSS J031300.36-670839.3. The Large Earth Finder is a high spatial resolution visible light Echelle spectrograph with red and blue channels, capable of operating in natural seeing during early operations. It is the only high-resolution visible spectrograph planned for the first decade of use on all the three of the world’s proposed Extremely Large Telescopes. The instrument will also be the first science instrument installed on the Giant Magellan Telescope.


The G-CLEF is being developed by astrophysicist Andrew Szentgyorgyi from the Center for Astrophysics | Harvard & Smithsonian.

Science Goals

  • Exoplanets: precise velocities, atmospheric properties
  • Stars: abundances, isotopes, and velocities
  • Dwarf galaxies: abundances, dark matter
  • Cosmology: chemical evolution, fine structure constant

Technical Specifications

Spectral resolutions:
19,000 | 35,000 | 108,000
Wavelength range:
3500 – 9500 Å
Velocity precision:
<50 cm/s per observation; <10 cm/s over time
High throughput, Medium Resolution, High resolution, precision radial velocity, multi-object (with MANIFEST fiber system)
Field of view (Imager):
300 arcmin2 (with MANIFEST fiber system)
For a full list of technical specifications, refer to our Science Book

Additional Resources

The G-CLEF spectrograph optical design: an update to the white pupil echelle configuration Furesz, G., et al. | Proc. SPIE 9147-343, (2014)
Feasibility studies for the detection of O2 in an Earth-like exoplanet Rodler, F. and Lopez-Morales, M. | ApJ, 781, 12, (2014)
A preliminary design for the GMT-Consortium Large Earth Finder (G-CLEF) Szentgyorgyi , A. et al. | Proc. SPIE 9147, Ground-based and Airborne Instrumentation for Astronomy V, 914726 (28 July 2014)
The GMT integral-field spectrograph (GMTIFS) conceptual design McGregor, P. J., Bloxham, G. J., Boz, R., Davies, J., Doolan, M. C., Ellis, M., Hart, J., Nielsen, J. J., Parcell, S., Sharp, R. G. and Stevanovic, D | Proc. SPIE 8446 (2012)
The GMT-Consortium Large Earth Finder (G-CLEF): an optical Echelle spectrograph for the Giant Magellan Telescope (GMT) Szentgyorgi, A, et al. | Part of SPIE Astronomical Telescopes + Instrumentation, 2016

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