On 19 October, the second edition of the CTAO Werner Hofmann Scientific Award was presented at the CTAO Construction Meeting in La Palma, Spain. Following a rigorous nomination and review process by an international panel of experts, the award was given to Dr. Georg Schwefer, a researcher at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg, Germany, for his groundbreaking work on Cherenkov event reconstruction and gamma-ray source analysis. Prof. Werner Hofmann presented Schwefer with the award, which included a medal, a monetary prize, and the opportunity to present his research at the 3rd edition of the CTAO Science Symposium that will take place during the 2027 IAU General Assembly in Rome, Italy.
Schwefer’s doctoral studies, recently completed and graded summa cum laude, centred on a fundamental challenge in very high-energy gamma-ray astronomy: maximising the precision with which Cherenkov telescopes determine the energy and arrival direction of incoming gamma rays, a crucial step for imaging astronomical sources in detail with the CTAO.
Initially tasked with integrating an existing reconstruction method as a standard tool within ctapipe (a data processing software for the CTAO), Schwefer quickly took the initiative a step further. Applying machine-learning techniques, he developed a completely new framework called FreePACT. This method is not only easier to use than its predecessor but also improves its performance, achieving an angular resolution of one arcminute above 10 TeV, which is unprecedented at photon energies above the X-ray band. Since its development, Schwefer has continued to refine FreePACT, speeding up its calculations and expanding the machine-learning approach to improve other features, such as gamma-hadron separation.
To demonstrate the observational impact of this improved resolution for the CTAO, Schwefer applied his methods to pulsar wind nebulae, energetic sources powered by rapidly spinning neutron stars. While these objects show well-resolved structures in X-rays, mapping their accompanying very high-energy gamma-ray emission has remained challenging due to limited former telescopes’ performance at multi-TeV energies. Schwefer’s work demonstrated that combining future observations from the CTAO’s southern array with existing X-ray data will make it possible to constrain the distributions of magnetic fields and high-energy electrons in these sources, with novel reconstruction algorithms like FreePACT significantly enhancing the sensitivity of the measurements. Alongside his core work on FreePACT, and building on his earlier Master’s research with the IceCube collaboration, he also conducted an analysis of Galactic diffuse gamma-ray emission using HAWC detector data and the Gammapy software package (the basis of CTAO science analysis tools), helping to refine the background models needed for future CTAO source analyses.
Launched in 2025 by the CTAO Central Organisation, the Werner Hofmann Scientific Award recognises early-career researchers who make significant theoretical, observational, or instrumental contributions to very high-energy gamma-ray astronomy and the CTAO. Named after Prof. Hofmann, a pioneering figure in the field, the award honours his lasting impact on the vision and design of the Observatory. The evaluation committee for the 2026 edition brought together experts from different countries and fields to select the winner: Emma de Oña Wilhelmi (DESY, Germany), Francesco Longo (INFN Trieste, Italy), and Roberta Zanin (CTAO Project Scientist).
Congratulations to Georg Schwefer on this well-deserved recognition!