Imaging Atmospheric Cherenkov Telescopes (IACTs) are ground-based detectors for high-energy gamma rays. The name IACT contains most of the characteristics of this type of instrument:
The MAGIC Telescopes are a continuation of work that started at the same site before 1987 with the HEGRA detector. Both experiments target the observation of high-energetic photons from sources within and outside our galaxy. The detection of these very-high-energy (VHE) gamma rays is only possible through the indirect observation via Cherenkov light. The atmosphere has only narrow windows for wavelengths to pass, it is transparent essentially only for visible and infrared light, and for long radio waves. But not for gamma rays, as shown in the diagram below for the entire electromagnetic spectrum.