Present

• ATA (Allen Telescope Array): A SETI project that will eventually have 350 radio dishes.
• Arecibo Observatory in Puerto Rico, operated by Cornell University: A 300-m dish.
• GBT (Green Bank Telescope): Two-acre dish in WV; Started operating in Aug, 2000.
• Haystack: MIT observatory using a 37-m radio telescope operating at wavelengths from 2.6 mm to 1.3 cm.
• HHT (Heinrich Hertz Submillimeter Telescope): Started operation in January 2000, looking at terahertz frequencies.
• HALCA (Space Very Long Baseline Interferometry): NASA program launched in 1996.
• VLA (NRAO's Very Large Array): 27 antennas in a Y pattern 22 miles across in New Mexico.

Future

• SKA (Square Kilometre Array): The largest telescope, an array of 30 interferometric stations, planned by a collaboration of different countries, will come into operation in the middle of the next decade (SFN article).
• Ideas: Space-based, lightweight inflatable telescopes?

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Past

• COBE (Cosmic Background Explorer): NASA mission launched in November 1989, to map the cosmic microwave background spectrum in different directions; led to the 1992 first discovery of fluctuations.

Present

• Archeops: A balloon-borne experiment designed to measure the temperature fluctuations of the CMB on a large region of the sky (about 30%) with a high angular resolution (10 arcminutes) and a high sensitivity.
• Boomerang: Maps the cosmic microwave background (CMB) using a balloon-borne telescope that circumnavigates Antarctica; a Canada-Italy-UK-US collaboration.
• CBI (Cosmic Background Imager): An array of 13 antennas designed to measure variations in the cosmic microwave background radiation on angular scales from 5 arc minutes to one degree, located at an altitude of 5000 meters near San Pedro de Atacama, in northern Chile.
• DASI (Degree Angular Scale Interferometer): A US experiment based at the South Pole, consisting of a 13-element interferometer designed to measure anisotropies in the cosmic microwave background radiation over a large range of scales with very high sensitivity.
• JCMT (James Clerk Maxwell Telescope): The largest astronomical telescope designed specifically to operate at submillimeter wavelengths; Used to study the Solar System, interstellar dust and gas, and distant galaxies; Situated on Mauna Kea at an altitude of 4092 m.
• WMAP (Wilkinson Microwave Anisotropy Probe): NASA mission, launched in June 2001 to measure differences in different directions (anisotropies) in the cosmic microwave background radiation (overview article); Much more sensitive than COBE, will also measure polarization, and cover the whole sky (BBC launch article).
• Maxima (Millimeter Anisotropy eXperiment Imaging Array): A US balloon experiment.
• SWAS (Submillimeter Wave Astronomy Satellite): In orbit 400 miles above the Earth's surface; Launched in 1998, operated by NASA with collaboration from several other institutions.

Future

• Planck: ESA mission scheduled for launch in 2009 together with Herschel, to study the origin and evolution of the Universe by observing the Cosmic Microwave Background radiation (0001, 0106 articles).
• South Pole Telescope: An 8-m array of 1,000 bolometers, that will be located at the National Science Foundation's South Pole Station, to take advantage of Antarctica's clear, dry skies; its scientific goal will be to understand the nature of dark energy.
• VSA (Very Small Array): A project to make images of the cosmic microwave background (CMB) radiation on angular scales around one degree.

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Past

• IRAS (Infrared Astronomical Satellite): A 0.6 m telescope placed in orbit at 30 km in 1983, operated for 10 months.
• ISO (Infrared Space Observatory): Launched in 1995, operated until May 1998; so far (2001) the best infrared space telescope astronomers have ever had: could have detected a 1-cm thick ice cube at a distance of 1000 km, solely by its heat emission.
• KAO (NASA's Kuiper Airborne Observatory): A 0.9-m reflector mounted on an airplane, retired from service in 1995.

Present

• ADONIS (ADaptive Optics Near Infrared System): An instrument, mounted at the European Southern Observatory 3.6-m telescope at the La Silla Observatory, Chile.
• GEMINI: Twin 8.1-m telescopes, GEMINI North at Mauna Kea in Hawaii and GEMINI South at Cerro Pachón in Chile.
• INGRID (Isaac Newton Group Red Imaging Device).
• IRTF (NASA's Infrared Telescope Facility): A 3.0-m telescope on Mauna Kea.
• Spitzer Space Telescope (formerly known as Space Infrared Telescope Facility): Part of NASA Origins Program; launched in August 2003, cooled with liquid helium to a few degrees above 0 K, and placed in an Earth-trailing orbit (Caltech site, images site).
• UKIRT (United Kingdom InfraRed Telescope): A 3.8-m telescope on Mauna Kea, the world's largest telescope dedicated solely to infrared astronomy.
• WIRE (NASA's Wide Field Infrared Explorer) Considered crippled because the spacecraft failed after launch in 1999, its tiny two-inch star camera was converted into a scientific instrument that measures star oscillation and searches for extrasolar planets (Caltech site).
• 2MASS (Two-Micron All-Sky Survey) (UMass site).

Future

• FIRST (ESA's Far Infra-Red and Submillimetre Telescope): Scheduled for launch on February 15, 2007 together with Planck; Renamed the Herschel Space Observatory.
• Herschel: ESA's infrared space observatory, now scheduled for launch in 2009; Will chart the formation rate of stars throughout cosmic history.
• SOFIA (Stratospheric Observatory for Infrared Astronomy): A 2.5-m reflecting infrared telescope, mounted inside a modified Boeing 747-SP aircraft; expected to fly into the stratosphere, at an altitude of 12,500 meters, open the telescope cavity door, and point its telescope at the heavens 3-4 nights a week for at least twenty years, starting in 2008.
• SPIRIT (Space Infrared Interferometric Telescope): Two telescopes at opposite ends of a 40-m beam that will provide views of planet, star and galaxy formations in unprecedented detail while examining the atmospheric chemistry of giant planets around other stars; Developed by a NASA-led team of university and industry partners.
• WISE (Wide-field Infrared Survey Explorer): NASA space telescope to be launched in 2008.

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Past

• IUE (International Ultraviolet Explorer): Launched in 1978, for wavelengths in the range 1200­3200 Å, was turned off in 1996.
• FUSE (Far Ultraviolet Spectroscopic Explorer): Launched in 1999 on a 3-year mission; Was extended and eventually ended in 2007; 800–1200 Å (9906 and 0106 articles).
• EUVE (Extreme UV Explorer): Launched in 1992, shut down in Jan 2001; Showed that the interstellar medium contains regions of ionized gases and is more transparent to UV radiation than what most scientists and astronomers expected; Detected more than 1000 sources, using wavelengths in the range 80–800 Å.

Present

• CHIPS (Cosmic Hot Interstellar Plasma Spectrometer): NASA satellite, launched in Jan 2003; will collect the first extreme ultraviolet spectra of truly diffuse emission from interstellar plasma and study the Local Bubble.
• HETE-2 (High Energy Transient Explorer): Built by a US/Japan/France/Italy collaboration led by MIT; Launched in October 2000 for UV, X-ray and gamma ray observation; in particular, to look for gamma ray bursts.
• Galex (Galaxy Evolution Explorer): NASA imaging and spectroscopic survey mission launched in April 2003, designed to map the global history and probe star formation and evolution over the redshift range 0 < z < 2 (80% of the history of the universe).

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Past

• HEAO-1: NASA X-ray orbiting telescope (Aug 1977 – Jan 1979).
• HEAO-2 (Einstein Satellite): NASA X-ray orbiting telescope (Nov 1978 – Apr 1981).
• ROSAT (Roentgen Satellite): Jun 1990 - Feb 1999.
• ASCA (Advanced Satellite for Cosmology and Astrophysics): Japanese/US orbiting X-ray telescope, launched in 1993; did not recover from historically big solar flare on July 14, 2000.
• Astro-E: NASA spacecraft launched in Feb 2000, but lost almost right away.
• BeppoSAX: Italian space agency X-ray satellite, that cracked the mystery of gamma-ray bursts by pinning down their locations on the sky well enough for astronomers to find their faint, visible-light afterglows; Deactivated in 2002, deorbited in 2003.

Present

• Chandra: NASA's orbiting X-ray telescope, launched in July 1999 by the space shuttle Columbia; 8-m long, with 1/2 arc-second resolution, on an oval orbit extending one-third of the way to the Moon (can't be reached by astronauts); looks at quasars, black holes, supernovas, pulsars, and intergalactic plasmas. (Harvard site, NYT site, current location.)
• Constellation X: A team of X-ray telescopes that will orbit close to each other in space, with emphasis on high throughput, high resolution spectroscopic observations of selected cosmic X-ray sources.
• EXIST (Energetic X-ray Imaging Space Telescope): For hard X-ray all-sky survey.
• HETE-2 (High Energy Transient Explorer): Built by a US/Japan/France/Italy collaboration led by MIT; Launched in October 2000 and operational from Feb 2001, for UV and X-ray and gamma ray observation; in particular, to look for gamma ray bursts.
• MAXIM (Milli-Arcsecond X-ray Imaging Mission): NASA mission with emphasis on very high resolution imaging observations of cosmic X-ray sources (NASA article).
• RXTE (Rossi X-Ray Timing Explorer): NASA X-ray satellite launched in 1995.
• XMM-Newton (X-Ray Multi-Mirror Mission): ESA's orbiting X-ray telescope.
• X-Ray Interferometry from the Center for Astrophysics and Space Astronomy at the University of Colorado.

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Past

• CGRO (Compton Gamma Ray Observatory, 1991-2000): Carried the Burst and Transient Source Experiment (BATSE), and the Energetic Gamma Ray Telescope Experiment (EGRET). Among many achievements, mapped the Milky Way using gamma rays from ²⁶Al.

Present

• NASA's gamma ray astrophysics program.
• AGILE (Astrorivelatore Gamma a Immagini LEggero): Italian space agency mission, launched in Apr 2007 and scheduled to be operational for three years.
• CANGAROO (Collaboration of Australia and Nippon for a GAmma Ray Observatory
  in the Outback): A project with various telescopes, in operation since 1992: Review article.
• GLAST (NASA's Gamma Ray Large Area Space Telescope): Launched in June 2008, for high-throughput observations of high energy cosmic gamma-ray sources; designed for a lifetime of 5 years and a goal of 10, will start with a one-year survey of the gamma-ray sky.
• HESS (High Energy Stereoscopic System): A ground-based array of Cerenkov telescopes deployed in Namibia by a European/African collaboration; looks for gamma rays produced by the most energetic particles in the Universe (images).
• HETE-2 (High Energy Transient Explorer): Built by a US/Japan/France/Italy collaboration led by MIT; Launched in Oct 2000 and operational from Feb 2001, for UV and X-ray and gamma ray observation; in particular, for gamma-ray burst position determination.
• INTEGRAL (ESA's INTErnational Gamma Ray Astrophysical Laboratory): Launched in October 2002, for high-resolution gamma-ray spectroscopy.
• MAGIC (Major Atmospheric Gamma Imaging Cherenkov, en español): A very large atmospheric imaging Cherenkov telescope on the Canary island of La Palma, with a mirror surface of more than 230 m², to detect cosmic g-rays at energies lower than any other terrestrial g-ray telescope.
• Swift (NASA's Gamma Ray Burst Explorer): Launched in November 2004, the first space mission for gamma-ray burst position determination.
• STACEE in New Mexico.

Future

• VERITAS (Very Energetic Radiation Imaging Telescope Array System): Ground-based, comprises 7 large-aperture (12-m diameter) Cherenkov telescopes, each equipped with an imaging camera; currently under construction.

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Cosmic Ray and Neutrino Telescopes

• Antares (Astronomy with a Neutrino Telescope and Abyss environmental RESearch): An underwater neutrino telescope that after a long development started working in 2006.
• AMANDA (Antarctic Muon and Neutrino Detector Array): A neutrino telescope near the South Pole, which looks downward - through the Earth - for arriving muons from the northern hemisphere, using strings of photomultiplier tubes lowered up to 2 kilometers into the ice.
• ARGO-YBJ (Astrophysical Radiation with Ground-based Observatory at Yangbajing): A Chinese-Italian collaboration involving researchers from 14 different institutions; Located in remote mountain valley in Tibet at an altitude of 14,000 feet, started operation in 2001.
• BESS (Balloon-borne Experiment with a Superconducting Spectrometer): A US-Japanese detector on a balloon which has flown nearly every summer since 1993 searching for evidence of an antimatter domain within our Universe.
• IceCube: A project for a detector like AMANDA but much larger, having an effective volume of 1 cubic kilometer below the South Pole Station, consisting of 4,800 PMTs on 80 strings.
• Pierre Auger Project: A cosmic ray shower detector being built over twelve hundred square miles of pampa in Argentina.
• SNO (Sudbury Neutrino Observatory).

Search for Antimatter

• NASA's BESS (Balloon-borne Experiment with a Superconducting Spectrometer).
• AMS (Alpha Magnetic Spectrometer), to be installed in the International Space Station in 2005.