News: The year 2026 will mark the completion of the Large-Sized Telescope (LST) array at the CTAO-North site on the Canary Island of La Palma, and we anticipate substantial progress in the construction of the first Middle-Sized Telescopes (MSTs) and Small-Sized Telescopes (SSTs) at the CTAO-South site within the ESO Paranal Observatory in Chile. Meanwhile, the current generation of IACTs continues to report exciting results, underscoring the remarkable dynamism and vibrant discoveries of the field.

After more than two decades of pioneering operations, the current generation of Imaging Air Cherenkov Telescopes (IACTs) -- specifically H.E.S.S., MAGIC, and VERITAS -- have firmly established very-high-energy (VHE, E > 100 GeV) gamma-ray astronomy as a mature and robust discipline. With over 300 known VHE sources, encompassing persistent, variable, and transient phenomena of diverse astrophysical natures, the field is thriving.

In parallel, a new generation of IACTs, the Cherenkov Telescope Array Observatory (CTAO), is poised to revolutionize VHE astronomy. The core of the future CTAO-North array, comprising four Large-Sized Telescopes (LSTs), is currently being installed at the Roque de los Muchachos Observatory on the Canary Island of La Palma, with its inauguration planned for October 2026. This 4-LST array is set to become the most sensitive IACT facility worldwide for several years, preceding the full completion of the CTAO. The first of these, LST-1, is already operational and delivering exciting scientific results. Concurrently, the construction of the first SSTs and MSTs at the CTAO-South site, located at the ESO Paranal Observatory in Chile, will see a significant boost in 2026, with completion of these first telescopes anticipated in 2027.

In this session, we will comprehensively revisit the science that can be addressed with VHE gamma rays. We aim to review the highlights and key discoveries achieved over the past decades and delve into the latest groundbreaking findings from current IACTs, while also preparing for the future opportunities presented by the CTAO. A central focus will be the transition path from current to next-generation telescopes. We will also place particular emphasis on the crucial synergies between current and future gamma-ray instruments and multiwavelength astronomy (across radio, optical, and X-ray bands), as well as the emerging field of multimessenger astronomy. This session provides a timely platform for the community to assess current capabilities, anticipate future discoveries, and strategize for an era where VHE gamma-ray observations will be increasingly integrated into broader astrophysical contexts.

Programme

• Reviews from Current-Generation IACTs: Highlights and cutting-edge results from H.E.S.S., MAGIC, and VERITAS.
• Path to the CTAO Era: Status, commissioning, and early scientific results from CTAO-LST (including LST-1 science).
• Future Gamma-Ray Observatories and Synergies: Overview of the full CTAO consortium (including MSTs and SSTs), ASTRI, and other ground-based facilities like LHAASO (LACT component) and their complementary roles.
• Time Domain and Transient Astronomy: Exploring the dynamic VHE sky, including GRBs, AGN flares, and Galactic transients.
• Synergies with other wavelengths and messengers: The VHE gamma-ray connection with X-rays, optical and radio, as well as with neutrinos, cosmic rays, and gravitational waves.
• Astrophysical Source Populations: Latest insights into Galactic (pulsars, PWNe, SNRs, binaries, GC) and Extragalactic (AGNs, Starburst Galaxies, Galaxy Clusters) VHE sources.
• Dark Matter and Fundamental Physics with VHE Gamma Rays.
• Data Science, Analysis Techniques, and Archives: Novel approaches to VHE data analysis, machine learning applications, and access to archival data.

Invited speakers

Scientific organisers

David Paneque, Max Planck Institute for Physics (MPP), Germany
Pol Bordas, University of Barcelona (UB), Spain
Alicia Lopez Oramas, Instituto de Astrofísica de Canarias (IAC), Spain
Mathieu de Naurois, Laboratoire Leprince-Ringuet (LLR), France
Gernot Maier, Deutsches Elektronen-Synchrotron (DESY), Germany
Fabian Schüssler, Institut de recherche sur les lois fondamentales de l'Univers (IRFU), France
Julian Sitarek, University of Lodz, Poland
Tomislav Terzic, University of Rijeka, Croatia
Simona Paiano, Instituto Nazionale di Astrofisica (INAF), Italy

Contact

dpaneque @ mpp.mpg.de, pbordas @ fqa.ub.edu, alicia.lopez @ iac.es, denauroi @ in2p3.fr, gernot.maier @ DESY.de, fabian.schussler @ cea.fr, jsitarek @ uni.lodz.pl, tomislav.terzic @ gmail.com, simona.paiano @ inaf.it