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.

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.