Observatories and telescopes: 4 to H

European Solar Telescope

The European Solar Telescope is a planned 4.2-meter solar telescope at Roque de los Muchachos Observatory on La Palma, Spain, promoted by 26 European research institutions.

European Southern Observatory

The European Southern Observatory, founded in 1962, is an intergovernmental organization of 16 European states that builds and operates observatories in Chile, including the Very Large Telescope.

Event Horizon Telescope

The Event Horizon Telescope is a global network of radio telescopes linked into one Earth-sized virtual telescope, which released the first image of a black hole in April 2019.

Extremely Large Telescope

The Extremely Large Telescope (ELT) is a 39-meter optical and infrared telescope the European Southern Observatory is building in Chile, to become the world's largest.

Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph

The Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph (FGS/NIRISS) is a Canadian Space Agency instrument on the James Webb Space Telescope that guides pointing and performs near-infrared imaging and spectroscopy.

First G-APD Cherenkov Telescope

The First G-APD Cherenkov Telescope (FACT) is a Cherenkov telescope on La Palma, Spain, the first with a camera of silicon Geiger-mode photodiodes instead of photomultiplier tubes.

Five-hundred-meter Aperture Spherical Telescope

The Five-hundred-meter Aperture Spherical Telescope, known as FAST or Tianyan, is a 500-meter radio telescope in Guizhou, China, completed in 2016, the world's largest single-dish radio telescope.

FlashCam

FlashCam is a fully digital Cherenkov camera for the medium-sized telescopes of the Cherenkov Telescope Array Observatory, assigned to its southern array site alongside NectarCAM.

Fred Lawrence Whipple Observatory

The Fred Lawrence Whipple Observatory is the largest field research station of the Smithsonian Astrophysical Observatory, located on Mount Hopkins in southern Arizona and established in 1968.

Fred Young Submillimeter Telescope

The Fred Young Submillimeter Telescope (FYST), formerly CCAT-prime, is a 6-meter submillimeter survey telescope on Cerro Chajnantor in Chile, run by a Cornell-led consortium, with first light expected in 2026.

GECAM

GECAM (Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor; Chinese name 极目) is a pair of Chinese microsatellites launched in 2020 to monitor the whole sky in X-rays and soft gamma rays for gamma-ray bursts.

Gemini Observatory

The Gemini Observatory is a pair of identical 8.1-meter optical and infrared telescopes, Gemini North on Maunakea in Hawai'i and Gemini South on Cerro Pachón in Chile.

Giant Magellan Telescope

The Giant Magellan Telescope is a 25.4-meter optical and infrared telescope under construction at Las Campanas Observatory in Chile's Atacama Desert, with seven 8.4-meter mirrors.

Giant Metrewave Radio Telescope

The Giant Metrewave Radio Telescope (GMRT) is a radio interferometric array of thirty 45-meter dishes near Pune, India, proposed by Govind Swarup and operational since 1995.

Goode Solar Telescope

The Goode Solar Telescope is a 1.6-meter off-axis solar telescope at Big Bear Solar Observatory in California, operated by NJIT and second in size only to DKIST.

Gran Telescopio Canarias

The Gran Telescopio Canarias (GranTeCan) is a 10.4 m optical and infrared telescope at the Roque de los Muchachos Observatory on La Palma, Spain, the world's largest since 2007.

Green Bank Telescope

The Green Bank Telescope is a 100-meter radio telescope in Green Bank, West Virginia, and the largest fully steerable radio telescope on Earth, dedicated in 2000.

Griffith Observatory

Griffith Observatory is a public astronomy observatory and science education center on Mount Hollywood in Griffith Park, Los Angeles, opened in 1935 and run by the city with free admission.

Haute-Provence Observatory

The Haute-Provence Observatory (Observatoire de Haute-Provence, OHP) is a French astronomy and atmospheric science site near Saint-Michel-l'Observatoire, where 51 Pegasi b, the first exoplanet around a Sun-like star, was discovered in 1995.

Hinode

Hinode (ひので, Japanese for "Sunrise"), known before launch as Solar-B, is a Japanese solar-observing satellite launched by JAXA in 2006 to study the Sun's magnetic field.

Hobby-Eberly Telescope

The Hobby-Eberly Telescope (HET) is a 10-meter fixed-elevation optical telescope at McDonald Observatory in west Texas, built for $13.9 million in 1997 and run by UT Austin, Penn State, and German universities.

Hydrogen Epoch of Reionization Array

The Hydrogen Epoch of Reionization Array, or HERA, is a radio telescope of 14 m dishes in the South African Karoo measuring neutral hydrogen from cosmic dawn.