Paranal Observatory First Choice to Host World’s Largest Array of Gamma-ray Telescopes

16 July 2015

On 15 and 16 July 2015, the Cherenkov Telescope Array (CTA) Resource Board decided to enter into detailed contract negotiations for hosting the CTA’s southern hemisphere array within the grounds of the Paranal Observatory, one of ESO’s sites in Chile. Similar negotiations for a northern site on La Palma are also starting.

The CTA project is an initiative to build the next generation of ground-based instruments designed for the detection of very high energy gamma-rays. Gamma rays are emitted by the hottest and most powerful objects in the Universe — such as supermassive black holes, supernovae and possibly remnants of the Big Bang. The array will provide valuable deeper insights into the high-energy Universe.

Although gamma rays don’t make it to the Earth’s surface, the CTA’s mirrors and high-speed cameras will capture short-lived flashes of the characteristic eerie blue Cherenkov radiation that is produced when the gamma rays interact with the Earth’s atmosphere. Pinpointing the source of this radiation will allow each gamma ray to be traced back to its cosmic source.

The CTA Resource Board is composed of representatives of ministries and funding agencies from Austria, Brazil, Czechia, France, Germany, Italy, Namibia, the Netherlands, Japan, Poland, South Africa, Spain, Switzerland and the United Kingdom. After months of negotiations and careful consideration of extensive studies of the environmental conditions, simulations of the science performance and assessments of construction and operation costs the Board has decided to start contract negotiations with ESO. The Namibian and Mexican sites will be kept as viable alternatives.

In order for the CTA to maximise its coverage of the night sky, the array will consist of about 100 telescopes on the Chile site in the southern hemisphere and about 20 telescopes at the northern site.

The Chile site for the CTA is less than ten kilometres southeast of the location of the Very Large Telescope, within the grounds of ESO's Paranal Observatory in the Atacama Desert. This is considered one of the driest and most isolated regions on Earth — an astronomical paradise. In addition to the ideal conditions for year-round observation, installing the CTA at the Paranal Observatory offers the CTA the opportunity to take advantage of the existing infrastructure (roads, accommodation, water, electricity, etc.) and access to established facilities and processes for the construction and operation of the telescope array.

Currently in its pre-construction phase, determination of the array sites is a critical factor in the CTA construction project.

More Information

The CTA aims to build the world’s largest and most sensitive high-energy gamma-ray telescope array. Over 1000 scientists and engineers from five continents, 31 countries (Argentina, Armenia, Australia, Austria, Brazil, Bulgaria, Canada, Chile, Croatia, Czechia, Finland, France, Germany, Greece, India, Ireland, Italy, Japan, Mexico, Namibia, the Netherlands, Norway, Poland, Slovenia, South Africa, Spain, Sweden, Switzerland, the United Kingdom, the United States of America and Ukraine) and over 170 research institutes participate in the CTA project. The CTA will serve as an open facility to a wide astrophysics community and provide a deep insight into the non-thermal, high-energy Universe. The CTA will detect high-energy radiation with unprecedented accuracy and approximately ten times the sensitivity of current instruments, providing novel insights into some of the most extreme and violent events in the Universe.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, Czechia, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.



Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

About the Announcement



The site of the future Cherenkov Telescope Array
The site of the future Cherenkov Telescope Array