Cherenkov Telescope Array

The CTA Headquarters (HQ): Bologna (Italy), the CTA Science Data Management Centre (SDMC): Zeuthen (Germany), 2 Telescope array sites: El Roque de los Muchachos Observatory on the island of La Palma (Spain) & Paranal Observatory in Atacama Desert (Chiile)


CTA is a global project to build the world’s largest and most sensitive ground-based observatory for gamma-ray astronomy at very-high energies. It will be also the first observatory open to the world-wide astronomy and physics communities, providing a unique resource of data products and tools. The project started in 2005, when scientists around the world proposed the first design concept for a next-generation gamma-ray facility, and we currently estimate the observatory to be completed in 2025. More than 1,400 members from 31 countries are engaged in the scientific and technical development of CTA.

The observatory will have two telescope array sites: at the Instituto de Astrofísica de Canarias’ (IAC’s) El Roque de los Muchachos Observatory on the island of La Palma (Spain) and near the European Southern Observatory’s (ESO’s) Paranal Observatory in the Atacama Desert (Chile). CTA’s three classes of telescope will cover an unprecedented broad energy range from 20 GeV to 300 TeV: the Large-Sized Telescope (LST), the Medium-Sized Telescope (MST) and the Small-Sized Telescope (SST). The plan for the Northern hemisphere site in La Palma includes 4 LSTs and 15 MSTs, whilst the Southern array will feature all three types of telescopes – 4 LTSs, 25 MSTs and 70 SSTs.

The preparation of the design and implementation of the observatory is managed by the CTA Observatory gGmbH (CTAO gGmbH), which is governed by Shareholders and Associate Members from a growing number of countries.  The CTA Headquarters is located in Bologna (Italy) in a shared building with the Department of Physics and Astronomy of the University of Bologna at the INAF campus. The building for the CTA Science Data Management Centre (SDMC), in charge of coordinating the processing and preservation of data, as well as to provide tools and support to scientific users, is being built on the DESY campus in Zeuthen (Germany).

The scientific challenge

Ground-based gamma-ray astronomy is a young field with enormous scientific potential. The current instruments H.E.S.S., MAGIC and VERITAS have been operated since 2003 and have already demonstrated the huge scientific potential of astrophysical measurements at TeV energies. CTA, built on the same technology, expects a tenfold increase in the number of known gamma-ray-emitting celestial objects, detecting more than 1,000 objects.

With its superior performance, CTA will bring a significant increase in discovery space, paving the way to new questions, and likely paradigm-changing discoveries. In particular, CTA has an unprecedented sensitivity to short (sub-minute) timescale phenomena, which places it as a key instrument in the future multi-messenger and multi-wavelength time domain astronomy. Transient phenomena are of great scientific interest, being associated with catastrophic events involving relativistic compact objects, such as neutron stars and black holes. The proposed targets comprise gamma-ray bursts, gravitational wave alerts, neutrino alerts, optical/radio transient events and serendipitous very-high-energy discoveries.

The main scientific challenges of CTA are related to expand the understanding of known objects and astrophysical mechanisms and even unveil new physics, gathered in three major study themes:

  1. Understanding the origin and role of relativistic cosmic particles

Relativistic particles seem to play a key role in great part of celestial objects, but the mechanisms for, and the sites of, cosmic acceleration are not yet fully understood nor are their impact on star-formation process and the evolution of galaxies. With its high angular resolution and large field of view, that allows fast surveys of the gamma-ray sky, CTA will be able to disentangle nearby sources providing accurate measurements on known and new sources and even proffer a census of particle accelerators in the Universe.

  1. Probing extreme environments

The most energetic electromagnetic radiation and highest-energy particles are usually associated to the most extreme environments in the Universe, such as those nearby neutron stars and black holes. From their vicinities, relativistic jets (beams of matter moving almost at the speed of light), violent winds and explosions arise, where gamma rays originate. Gamma-ray emission can therefore act as a probe of these surroundings and help to understand the emission and acceleration processes that govern there.

  1. Exploring frontiers in physics

Dark matter is thought to account for a large part of the total mass of the Universe and still, its nature remains to be one of the greatest mysteries in science. The improved energy resolution will increase CTA’s ability to look for features in the spectrum of gamma rays produced when dark matter particles (believed to be Weakly Interacting Massive Particles, or WIMPs) annihilate one another when they interact. Moreover, CTA may also provide evidence of deviations from the Einstein’s theory of relativity as well as the existence of axion-like particles and answers to the contents of cosmic voids. 

Some of the most promising discoveries and interesting sources to address these Key Science Themes will come from our own Galaxy, the Milky Way, which holds remnants of supernova explosions (SNRs) and pulsar wind nebulae (PWNe), binary systems hosting a neutron star or a black hole, and rapidly spinning, magnetized and ultra-dense stars known as pulsars. Beyond the Milky Way, CTA will search for star-forming galaxies, galaxies with supermassive black holes in their centres (called Active Galactic Nuclei) and even galaxy clusters.

The Impact

More info soon.