AGN's (Active Galactic Nuclei) Nov. 30, 2017 Narrated animation describing AGN's (Active Galactic Nuclei) An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much higher than normal luminosity over at least some portion – and possibly all – of the electromagnetic spectrum. Such excess emission has been observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The rad