Ground-based gamma-ray astronomy is a young research field. The possibility of astrophysical measurements at teraelectronvolt (TeV) energies was demonstrated in 1989 with the detection of a clear signal from the Crab nebula above 1 TeV with the Whipple 10m imaging atmospheric Cherenkov telescope (IACT). Since then, the instrumentation and techniques have evolved to the extent that a flourishing new scientific discipline has been established, with the detection of more than 200 sources and a major impact in astrophysics and more widely in physics. The current major arrays of IACTs: H.E.S.S., MAGIC, and VERITAS, have demonstrated the huge physics potential at these energies as well as the maturity of the detection technique. Many astrophysical source classes have been established, some with many well-studied individual objects, but there are indications that the known sources represent the tip of the iceberg in terms of both individual objects and source classes.

Teams from IN2P3 and the University of Tokyo have been strongly involved in the current generation of IACTs, respectively, within H.E.S.S. and MAGIC collaborations. These teams have contributed to the publication of major results in various topics such as the understanding of the origin of cosmic-ray particles, probing extreme environments in our Universe, or exploring the nature of dark matter. For more than a decade, both teams contributed to a common effort to design and build the next generation of the IACT network, the Cerenkov Telescope Array (CTA). CTA is designed to be ten times more sensitive and has unprecedented accuracy in its detection of high-energy gamma rays. It will be composed of more than 100 telescopes located in the northern and southern hemispheres. Three classes of the telescope will be distributed in the northern and southern hemispheres based on their sensitivity: the Small-Sized Telescope (SST), Medium-Sized Telescope (MST), and Large-Sized Telescope (LST). Amongst those CTA sub-projects, both teams are strongly involved in the design, contribution, and commissioning of the LST, the University of Tokyo being the leading institute.

ILANCE will strengthen the partnership between IN2P3 and the University of Tokyo over a period of time that coincides with the commissioning and very first operations of the CTA telescopes, in particular the LSTs built on the Northern CTA site. Strengthened collaboration between teams will allow maximizing the outcome of the early science available with first observations of CTA.

CTA EXPERIMENT     https://www.cta-observatory.org

HESS EXPERIMENT      https://www.mpi-hd.mpg.de/hfm/HESS

MAGIC EXPERIMENT      https://magic.mpp.mpg.de