Gamma-ray Astronomy: Site negotiations for Cherenkov Telescope Array started

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On the 10th April 2014, the 12 country delegates mandated by their governments to decide about the start of site negotiations for CTA (Cherenkov Telescope Array), to which contribute the CNRS and the CEA, met in Munich. Two sites in the southern hemisphere are likely to welcome this future network of new generation telescopes in high energy astronomy : Aar in Namibia and ESO (*) in Chile. The site Leoncito in Argentina is meanwhile a third option. With this selection of potential sites in the southern hemisphere, an important step towards the realization of the international CTA project has been made.

The CTA observatory will lead to explore the cosmos at the highest gamma photon energies and provide an-order-of-magnitude jump in sensitivity over current instruments, providing novel insights into some of the most extreme processes in the Universe.

CTA will consist of more than 100 Cherenkov telescopes of 23 m, 12 m and 4 m diameters for its southern site, which will be the main site, and a smaller site in the northern hemisphere. A set of potential candidate sites have been identified in the northern and southern hemispheres, and in-depth studies of the environmental conditions, simulations of scientific performance, and evaluation of the construction costs were made.

The selection committee of the sites (SSC: Site Selection Committee), composed of international experts in the evaluation of sites for astronomical observatories, reviewed the studies and provided an independent assessment of the various candidate sites.

After they took note of the report of the SSC, the delegates representing Argentina, Austria, Brazil, France, Germany, Italy, Namibia, Poland, Spain, South Africa, Switzerland and the UK decided, based on the 75% majority required, to start the negotiations on the two sites located in the southern hemisphere, namely Aar in Namibia and ESO(*) in Chile, keeping Leoncito in Argentina as a third option. After the negotiations, finally one site will be selected at the end of the year 2014.

Additional studies concerning the implantation of the CTA observatory in the northern hemisphere emerged – candidate sites are located in Mexico, Spain and the United States. As a consequence, the representatives decided to postpone their decision and ask the Board of CTA – gathering departments and agencies – to make progress on this point. The decision to launch negotiations on the choice of the northern hemisphere site will be taken as soon as possible.

CTA – the Cherenkov Telescope Array – is a multinational, world-wide project to construct a unique instrument exploring the cosmos at the highest photon energies. Over 1000 scientists and engineers from 5 continents, 28 countries and over 170 research institutes participate in the CTA project.

The French laboratories involved in the CA consortium are :

  • Astroparticule et cosmologie – APC (Université Paris Diderot-Paris 7/CNRS/CEA/Observatoire de Paris)
  • Centre d’Etudes Nucléaires Bordeaux-Gradignan – CENBG (Université Bordeaux, CNRS)
  • Centre de physique des particules de Marseille – CPPM (Aix-Marseille Université,/CNRS)
  • Institut de planétologie et d’astrophysique de Grenoble – IPAG (CNRS/Université Joseph Fourier)
  • Institut de recherche en astrophysique et planétologie – IRAP (Université Paul Sabatier Toulouse III/CNRS)
  • Institut de recherche sur les lois fondamentales de l’Univers – Irfu (CEA)
  • Laboratoire d’Annecy-le-Vieux de physique des particules – Lapp (CNRS/Université de Savoie)
  • Laboratoire Leprince-Ringuet – LLR (CNRS/École Polytechnique)
  • Laboratoire de physique nucléaire et de hautes énergies – LPNHE (CNRS / Université Pierre et Marie Curie / Université Paris Diderot-Paris 7)
  • Laboratoire Univers et particules de Montpellier – LUPM (CNRS – Université Montpellier 2)
  • Observatoire de Paris
  • Laboratoire Univers et théories- LUTH (CNRS/ Observatoire de Paris/ Université Paris Diderot)
  • Galaxies, Etoiles, Physique, Instrumentation – GEPI (CNRS/ Observatoire de Paris/ Université Paris Diderot)

* ESO – European Southern Observatory

IRAP Contact

Jürgen Knödlseder,, 06 24 36 25 47

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