High Energy Stereoscopic System, Astronomical research complex in Khomas Region, Namibia

The High Energy Stereoscopic System is an observatory with five telescopes of different sizes working together. Four telescopes have 12-meter mirrors arranged in a square pattern, while a central telescope in the middle has a 28-meter mirror for detecting gamma rays from space.

The facility began operations in 2002 and was expanded a decade later with the addition of the central telescope called HESS II. This expansion improved the observatory's ability to detect and study gamma rays from distant cosmic sources.

The acronym H.E.S.S. honours Victor Hess, who discovered the extraterrestrial origin of cosmic rays; it also stands for the stereoscopic observation of air showers by several telescopes combined into one system. The site is run on the farm Göllschau near the Gamsberg, an area known for its optical quality.

H.E.S.S. stands on the farm Göllschau in the Khomas highlands near the Gamsberg, a site chosen for the optical quality of its sky. It is a working research facility, not open to visitors, so the array is not accessible for tours. The five telescopes are laid out like the five pips on a die, with the 28 m telescope at the centre of the 120 m square formed by the four smaller ones.

In 2004, this observatory achieved a scientific milestone by becoming the first instrument of its kind to spatially resolve a distant cosmic gamma-ray source. This breakthrough demonstrated just how precisely these instruments could capture details from space.