On Friday, 18 September 2026, the Dal Ben S.p.A. headquarters in San Stino di Livenza, Italy, hosted an exceptional gathering. National and regional media representatives, alongside members of the CTAO SST Collaboration and the CTAO Central Organisation, came together for an exclusive press event to witness the shipping preparations for the very first Small-Sized Telescope (SST) destined for Chile. During the day, attendees enjoyed a dynamic demonstration of a fully assembled telescope’s movements, while also bidding a “final farewell” to the departing SST, witnessing the live sealing of its shipping crates ahead of its journey. The event also featured a welcome address by Dal Ben S.p.A. CEO Gabriele Dal Ben, followed by insightful speeches from institutional leaders, including CTAO Director General Stuart McMuldroch and INAF President Roberto Ragazzoni. Additionally, experts like Gianpiero Tagliaferri (PI of the SST Collaboration) and Stefano Stanghellini (CTAO Telescope Coordinator) delved into the technical aspects of the SSTs and the Observatory, before a guided tour showcased the parts and assembly process of 26 other telescopes.
To understand the magnitude of this shipment, we must look at the bigger picture. The CTAO is set to become the world’s largest and most powerful ground-based gamma-ray observatory. To cover an unprecedented energy range, the Observatory will employ three classes of telescopes: along with the SST, the Observatory will benefit from Large-Sized Telescopes (LST) and Medium-Sized Telescopes (MST). More than 60 telescopes will be built across the CTAO’s two array sites, one in each hemisphere: CTAO-North in La Palma, Spain, and CTAO-South in the Atacama Desert, Chile. The latter is the destination of this first SST.
As the name suggests, the SSTs are the smallest telescopes in the CTAO array, yet they are a marvel of optical engineering designed to capture the Universe’s most extreme accelerators. Standing 9 metres tall, they are unique within the Observatory for utilising a dual-mirror design, based on a modified Schwarzschild-Couder optical configuration. This setup features a 4.3-metre primary mirror made of 18 hexagonal segments that reflects light onto a 1.8-metre monolithic secondary mirror, guaranteeing high spatial resolution across a very wide field of view and allowing for a highly compact focal plane.
The SSTs are specifically optimised to detect the highest end of the CTAO’s energy range, spanning from 2 TeV to 300 TeV. Because the particle showers generated by these extreme gamma rays produce abundant Cherenkov light but are incredibly rare, smaller telescopes are sufficient to collect the light, but a vast number of them are required to increase the probability of detection. Consequently, a total of 37 SSTs, as well as 14 MSTs, will be deployed across an area of three square kilometres in CTAO-South.
Italy plays a fundamental and multi-faceted role in bringing this global endeavour to life. The country is not only a founding member of the CTAO ERIC (also known as Central Organisation), but it also hosts its headquarters in Bologna. Moreover, national teams lead the development of the SSTs. Coordinated by Italy’s National Institute for Astrophysics (INAF), the international SST Collaboration brings together research institutes and universities from Australia, Brazil, France, Germany, Italy, Japan, the Netherlands, the UK, and the USA.
This scientific leadership is complemented by a strong industrial contribution. The manufacturing of the telescopes is a testament to Italian industrial excellence, with Dal Ben S.p.A. taking charge of the mass production of the complex electromechanical structures of the SSTs. Crucially, the production of these components received a strong acceleration thanks to the CTA+ programme, funded by the National Recovery and Resilience Plan (PNRR) under the NextGenerationEU initiative and approved by MUR.
Ultimately, this first SST will be deployed at CTAO-South, located at the European Southern Observatory’s (ESO) Paranal Observatory in Chile’s Atacama Desert. Guided by the Central Organisation’s CTAO-South team, the site is rapidly taking shape with significant preparation work already accomplished: 17 kilometres of on-site roads have been constructed, and the foundations for both the SSTs and MSTs are now complete. Furthermore, the first accommodations for the assembly and testing teams have been built, and the installation of the telescope power supply system is imminent, ensuring the site is perfectly ready to welcome this very first SST.
As this pioneering telescope leaves its Italian birthplace, it carries with it the ingenuity of a worldwide collaboration, ready to unlock the most extreme and violent secrets of the cosmos under the pristine Chilean sky.