Cherenkov Telescope Array (CTA)

Schematic of the Cherenkov Telescope Array
(Credit: CTA Collaboration)

CTA, consisting of two sites, one in the northern hemisphere and one in the southern hemisphere, is an international initiative to build the next generation ground-based, very high energy gamma-ray observatory. CTA will represent an improvement in sensitivity over current Imaging Atmospheric Cherenkov Telescope arrays of a factor of ten, whilst simultaneously extending the energy range covered and providing improved energy and spatial resolution. CTA will survey the sky about 200 times faster than current instruments and will outperform the Fermi satellite by over four orders of magnitude in sensitivity.

Each site will contain an array of telescopes that will allow the detection of gamma-ray induced cascades over a large area. Covering a large area will increase the number of detected gamma-rays, improving angular resolution and suppression of cosmic-ray background events. CTA will have a large discovery potential in key areas of astronomy, astrophysics and fundamental physics research. These include the study of the origin of cosmic rays and their impact on the constituents of the Universe, the investigation of the nature and variety of black hole particle accelerators and effects of quantum gravity.


Quick Facts about CTA

Telescope Sizes

3 sizes of telescopes; Small Size Telescope; Medium Size Telescope; and Large Size Telescope. Deployed in the northern and southern hemisphere to optimise the energy detection profiles of the arrays.


Two separate sites in the northern and southern hemisphere containing telescope arrays.

International Collaboration

Over 1,350 scientists in over 210 institutes in 32 countries

UK Collaboration

Over 40 Scientists

Science Challenges

The CTA research programme is key to achieving STFC’s science challenges and will help to answer the following questions:

  • How did the universe begin and how is it evolving?
  • What are the fundamental constituents and fabric of the universe and how do they interact?
  • When were the first stars, black holes and galaxies born?
  • How do galaxies evolve?
  • What is the physics of the early Universe?
  • How are stars born and how do they evolve?
The Gamma-ray Cherenkov Telescope prototype design with reduced size circular primary mirror petals

The Gamma-ray Cherenkov Telescope prototype design with reduced size circular primary mirror petals
(Credit: CTA Collaboration)

UK Involvement

CTA is currently in its pre-production phase with the first telescopes now either constructed and under test or nearing completion. UK scientists are leading aspects of this programme and have contributed significantly to the progress of CTA to date. So far the UK has developed a high-performance dual-mirror design for the optics and structure of the small sized telescopes (SST) which has made production of the SSTs economically viable. In addition, UK scientists proposed the optical calculations for the Gamma-Cherenkov Telescope (GCT), an SST, as well as the first mechanical structure of the telescope which is now being used. CTA-UK groups, with the support of STFC, have designed cameras for the GCT using multi-anode and silicon photomultipliers. The UK groups have formed a collaboration with European, Japanese, Australian and US groups to construct GCTs for CTA, with UK involvement foreseen primarily in camera construction, but also in studies of improved mirrors and aspects of the structure telescope structure, as well as in the CTA data pipeline.


The CTA-UK group has considerable experience in knowledge exchange with industrial partners. This will allow the technology developed as part of the UK’s contribution to filter down into other industrial applications benefiting the economy. The amplifiers designed as a requirement for the GCT camera are high-speed, low-noise, low-power and cheap. These amplifiers could be used in neutron detection systems. The amplifiers may also be used in battery-powered hand held devices.

The construction of CTA will cost approximately €400M and will require substantial industrial involvement. This will provide many opportunities for UK industrial contracts of both major and minor components. A “CTA Industry Day” was held at Daresbury Laboratory in which representatives from industry learnt about the type of work required. Several of the connections made during the day will be exploited.

The CTA-UK group regularly takes part in outreach events for schools and the general public. PhD students and Postdoctoral Research Assistants are also at the heart of CTA. Investing in the next generation of scientists is key to the future development of state-of-the-art technology.

Science and Technology Facilities Council Switchboard: 01793 442000