... Rationale . ... Optical image of Centaurus A taken with the MPG/ESO 2.2-m telescope. ... Centaurus A (NGC 5128) is a spectacular giant radio galaxy. It is by far the closest galaxy in the Universe with an active, supermassive black hole, and it was the first extragalactic radio source to be identified (by CSIRO radiophysics astronomers Bolton, Stanley and Slee using cliff-top interferometry at Dover Heights ). ... X-ray image of Centaurus A taken with Chandra. ...