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The GMT-Consortium Large Earth Finder (G-CLEF) is a fiber-fed, optical echelle spectrograph that will be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF is a general-purpose echelle spectrograph with precision radial velocity (PRV) capability. The radial velocity (RV) precision goal of G-CLEF is 10 cm/sec; necessary for detection of Earth-sized exoplanets orbiting Solar-type stars in their habitable zone. This imposes challenging stability requirements on the optical mounts and spectrograph support structures especially when considering the instrument’s operational environment. G-CLEF’s accuracy will be influenced by thermal effects, ambient air pressure, vibration, and micro gravity vector variations caused by normal telescope slewing. The design and fabrication schedule for the G-CLEF spectrograph and ancillary systems will lead the GMT telescope by approximately 5 years, therefore, we will design and build an interim installation configuration for G-CLEF at Magellan’s 6.5m telescopes. This will allow us to complete and commission the spectrograph. During this period, we will collect at least 5 years of data at Magellan from roughly 2025 to 2030. We will also optimize major subsystems including; spectrograph optics and mechanics, vacuum systems, thermal control, and vibration isolation. G-CLEF completed its Critical Design Phase for the GMT configuration in 2018. In this paper, we provide an update on the G-CLEF spectrograph’s opto-mechanical design, including the GMT front end assembly. We also provide an update on our current fabrication status including procurement of camera optics, reflective optics, carbon-fiber optical bench, camera optical mounts, and vacuum chamber assembly. We also discuss adaptations required to support the interim deployment at Magellan.
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