Cherenkov Telescope Array Observatory CTAO (astroparticle physics)

CTA's southern hemisphere site © CTAO

The Cherenkov Telescope Array Observatory (CTAO) will be the largest new-generation ground-based observatory for very high energy gamma-ray astronomy. It will be formed of two telescope arrays deployed in the southern hemisphere at the Paranal astronomical observation site (Chile), operated by the European Southern Observatory (ESO), and in the northern hemisphere at the La Palma astronomical observation island (Canary Islands, Spain), operated by the Canary Islands Institute of Astrophysics (IAC). This means the CTAO will be the first ground-based observatory to cover the entire sky. The Observatory will be set up as a European Research Infrastructure Consortium (ERIC), with its headquarters in Bologna, Italy. 

The CTAO is an international scientific collaboration to build the Cherenkov Telescope Array (CTA), a world-leading astroparticles research infrastructure. It is hoped that its technical performance will allow fundamental breakthroughs in the field of high energy astrophysics, but also more generally in cosmology and fundamental physics. 

A consortium of scientists and institutes from around the world is currently in the process of designing CTA. Construction is scheduled to start in 2022. The first configuration of the telescope array is expected to cost about EUR 330 million. The array is due be fully operating by 2025 and will have an expected lifetime of 30 years. 

The northern hemisphere site is located on the island of La Palma in the Canary Islands. The southern site is located at ESO’s Paranal Observatory. 

The largest terrestrial observatory for very high energy gamma-ray astronomy

The CTAO will be the world's largest high-energy gamma-ray observatory. Its two telescope arrays will detect gamma rays with unprecedented accuracy and sensitivity. CTA will also provide unique cooperation opportunities for particle physics and astrophysics communities around the world. It will also provide the nascent astroparticle physics community with a truly international research organisation.

CTA will be able to detect high-energy gamma rays from cosmic sources ranging from 20 gigaelectronvolts [GeV] to 300 teraelectronvolts [TeV]. It will be sensitive to the most powerful cosmic particle accelerators in the universe. CTA will have vast scientific potential; for example, it will give greater insight into the role of high-energy cosmic particles, the functioning of black holes and pulsars, and the search for dark matter. 

CTA is also an IT challenge: the total volume of data to be managed by the Observatory's archives will be around 25 PB per year. Images of the gamma-ray sources will be reconstructed from observations of numerous particle showers captured by the cameras of the CTA telescopes. This data, which will be distributed from a data centre in Zeuthen (Germany), will be freely accessible.

LST prototype (LST-1), northern hemisphere site, La Palma, Spain © CTAO

Swiss participation

The University of Zurich, University of Geneva and the ETH Zurich have been involved in CTA since the early 2000s. Having a privileged role in the project design, in early 2020 the University of Geneva, with federal support, took the lead in consolidating the user base in Switzerland necessary for a possible future Swiss membership in CTAO ERIC. 

CTAO ERIC could be established by mid-2022. Headed up by Italy, further founding members would include Austria, Czech Republic, France, Germany, Poland, Slovenia, Spain and ESO. Switzerland is planning to join CTAO ERIC as a founding observer. In addition to the circle of future members of CTAO ERIC, institutions in several countries, in particular Japan, Australia, Brazil, the USA and the UK, will also be involved in the construction.

CTA is of considerable scientific interest to Switzerland and the world in terms of data production and analysis techniques, including machine learning and modern imaging techniques. Moreover, there will be opportunities for specialised industries to be involved in construction of the telescopes. 

SERI is participating in the ongoing negotiations on the establishment of the CTAO ERIC organisation, along with the future member states.


SERI, Xavier Reymond
Head of the Swiss delegation

University of Geneva
Prof. Teresa Montaruli
Swiss CTAO Collaboration coordinator

ETH Zurich
Prof. Adrian Biland
Science delegate for Switzerland

SERI, Simon Berger
Swiss delegate to the Board of Government Representatives