News: 2026 marks a turning point for CTAO construction. At CTAO-North, the three remaining Large-Sized Telescopes (LST) are advancing rapidly toward a sub-array inauguration planned for October. Simultaneously, CTAO-South will complete roads and foundations, enabling the start of telescope assembly toward the end of the year. In parallel, the current generation of IACT continues to deliver 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 (IACT) -- 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, the next generation VHE gamma-ray facility and the first gamma-ray observatory, based on the array of IACT technique, the Cherenkov Telescope Array Observatory (CTAO), has officialy started the construction, and is rapidly emerging onto the scientific landscape. The core of the future CTAO-North array, comprising four LST, is currently being installed at the Roque de los Muchachos Observatory on the Canary Island of La Palma, and will start its commissioning phase soon. The first LST, known as LST-1, is being commissioned and is already delivering exciting scientific results. Once the other three LST become operational and join it, they will form the core of the first intermediate configuration at CTAO-North (4LST + 1 Medium-Sized Telescope), driving its scientific performance.

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 IACT experiments, while also preparing for the future opportunities presented by the CTAO, as an open, proposal-driven observatory. A central focus will be the transition path from current to next-generation facilities. 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 IACT: Highlights and cutting-edge results from H.E.S.S., MAGIC, and VERITAS.
• Path to the CTAO Era: Status, commissioning, open science data challenge, and early science plan with a particular emphasis on the scientific results obtained with the LST-1.
• Future Gamma-Ray Facilities: ASTRI-MiniArray, LHAASO, LACT, SWGO, emphasizing their complementarity.
• Foreseen scientific exploitation of the CTAO, based on detailed simulation studies conducted by the CTAO Consortium.
• 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

TBD

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
Michele Doro, University of Padova, 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,michele.doro @ unipd.it