Keck Observatory

Keck Observatory consists of two 10-meter adaptive optics (AO) reflector telescopes (Keck I and Keck II) near summit of Mauna Kea in Hawaii, at an elevation of 4,145 meters (13,600 ft). When they went into operation in the 1990s, they represented a substantial increase in the size of optical telescopes and as of 2025, ~10 meters remains largest class of individual optical telescopes in operation. The two can operate as an optical interferometer with a baseline of 85 meters, known as the Keck Interferometer (KI). The observatory is named for W. M. Keck whose foundation funded it. Its instruments include:

• HIRES "High Resolution Echelle spectrometer" - good instrument for measuring stellar radial velocity to identify and characterize extra-solar planets.
• LRIS "Low Resolution Imaging Spectrograph".
• MOSFIRE "Multi-object Spectrometer For Infra-red Exploration".
• OSIRIS "OH-suppressing Infrared Imaging Spectrograph".
• KPF "Keck Planet Finder" - high resolution spectrograph.
• DEIMOS "Deep Extragalactic Imaging multi-object spectrograph".
• ESI "Echellette Spectrograph and Imager".
• KCWI "Keck Cosmic Web Imager" - integral field spectrograph.
• NIRES "Near-Infrared Echellette Spectrometer".
• NIRC-2 "near infrared camera" (2nd generation).
• NIRSPEC "Near infrared Spectrometer" - includes the Keck Planet Imager and Characterizer (KPIC) infrared extreme adaptive optics system.
• SCALES - "Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy".

KCRM ("Keck Cosmic Reionization Mapper") is a 2023 upgrade to KCWI. Some previously listed instruments:

• NIRC (predecessor to NIRC-2).
• LWS "Long Wavelength Spectrometer".

A future upgrade in development is KAPA (for "Keck All-Sky Precision Adaptive Optics"), an improved AO system.