Science News

Final Agreements Signed for CTA’s Southern Hemisphere Site in Chile

Published on 20.12.2018


he Cherenkov Telescope Array Observatory (CTAO) Council and European Southern Observatory (ESO) have signed the final agreements needed for CTA’s southern hemisphere array to be hosted near ESO’s Paranal Observatory in Chile.

Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) or National Commission for Scientific and Technological Research. With these three agreements in place, the CTAO will be able to begin construction on the southern site. The hosting agreement with the Instituto de Astrofísica de Canarias (IAC) is already in place to host CTA’snorther n hemisphere arrayat the Observatorio del Roque de los Muchachos in La Palma, Spain. Construction on both the northern and southern arrays is expected to begin in 2020.

Federico Ferrini, Managing Director of the Cherenkov Telescope Array Observatory (CTAO), met ESO’s Director General, Xavier Barcons at the Chilean Ministry of Foreign Affairs in Santiago. Together with ESO’s Director for Operations, Andreas Kaufer, they signed the agreement for the construction and operation of the CTA’s southern array at ESO’s Paranal-Armazones site in northern Chile. Preceding the signing of the two agreements on Wednesday, Ferrini met CONICYT’s Executive Director, Christian Nicolai Orellana on 17 December to sign the scientific collaboration agreement between the two parties.

CTA will be the next generation ground-based instrument in the detection of gamma rays, which are very high-energy electromagnetic radiation emitted by the hottest and most powerful objects in the Universe — such as supermassive black holes, supernovae and possibly remnants of the Big Bang. To provide access to the whole sky, the CTA Observatory will have two sites, with 19 telescopes in the northern hemisphere and 99 in the southern hemisphere.

CTA’s southern site is less than ten kilometres southeast of the location of the Very Large Telescope at ESO's Paranal Observatory in the Atacama Desert, and only 23 kilometres from the construction site of the upcoming Extremely Large Telescope. This is one of the driest and most isolated regions on Earth — an astronomical paradise. In addition to the ideal conditions for year-round observation, installing CTA at the Paranal Observatory brings the advantages of ESO’s expertise and infrastructure.

Current gamma-ray telescope arrays only consist of a handful of individual telescopes, but CTA — with its larger collecting area and wider sky coverage — will be the largest and most sensitive array of gamma-ray telescopes in the world, with unprecedented accuracy and 10 times more sensitive than existing instruments.

Although the Earth’s atmosphere prevents gamma rays from reaching the surface, CTA’s mirrors and high-speed cameras will capture the short-lived flashes of eerie blue Cherenkov radiation produced when gamma rays interact with the atmosphere. Detection of this Cherenkov light will allow the gamma ray to be traced back to its cosmic source.

The scientific scope of CTA is extremely broad: from understanding the role of relativistic cosmic particles to the search for dark matter. CTA will explore the extreme Universe, probing environments from the immediate neighbourhood of black holes to cosmic voids on the largest scales. It may even lead to brand new physics as it studies the nature of matter and forces beyond the Standard Model.

More than 1,400 scientists and engineers from 31 countries are engaged in the scientific and technical development of CTA. The Observatory will be constructed and operated by the CTAO ERIC, which is governed by member states and associate members from a growing number of countries.

Shareholders of CTAO gGmbH – the entity that is preparing for the CTAO ERIC – are representatives of ministries and funding agencies from Australia, Austria, Czech Republic, France, Germany, Italy, the Netherlands, Japan, Slovenia, South Africa, Spain, Switzerland and the United Kingdom [1].


[1] The Netherlands and South Africa attend as observers.

More Information

CTA is a global initiative to build the world’s largest and most sensitive high-energy gamma-ray observatory. More than 1,400 scientists and engineers from 31 countries across five continents (Armenia, Australia, Austria, Brazil, Bulgaria, Canada, Chile, Croatia, the Czech Republic, Finland, France, Germany, Greece, India, Ireland, Italy, Japan, Mexico, Namibia, the Netherlands, Norway, Poland, Slovenia, South Africa, Spain, Sweden, Switzerland, Thailand, the United Kingdom, the United States of America and Ukraine) and more than 200 research institutes are participating in the CTA project. CTA will be the foremost global observatory for very high-energy gamma-ray astronomy over the next decade and beyond and will be the first ground-based gamma-ray astronomy observatory open to the world-wide astronomical and particle physics communities.

CTA’s northern hemisphere site & the ICCUB

Rendering Credit: Gabriel Pérez Diaz, IAC, SMM

CTA’s northern hemisphere site is located on the existing site of the Instituto de Astrofisica de Canarias’ (IAC’s) Observatorio del Roque de los Muchachos in Villa de Garafia on the island of La Palma.

While the southern hemisphere array will span the entire energy range of CTA, covering gamma-ray energies from 20 GeV to more than 300 TeV, the northern hemisphere array will be more limited in size and will focus on the low- and mid-energy ranges from 20 GeV to 20 TeV. For this reason, the northern hemisphere site will not host any Small-Sized Telescopes, which are tuned to capture the highest-energy gamma rays. The plan is for the site to host four Large-Sized Telescopes to capture the low-energy sensitivity of CTA and 15 Medium-Sized Telescopes to cover CTA’s core energy range.

0n October 2018 was celebrated the inauguration of the first prototype Large-Sized Telescope (LST). The Institute of Cosmos Sciences (ICCUB) had an important participation in the technological development of the LST-1, contributing to the design of one of the signal amplification devices and to the definition of the scientific objectives of the project.