A team of European astronomers has used a virtual observatory to find 30 previously undiscovered black holes. The team combined images from several observatories (Hubble, Chandra, ESO) in many wavelengths of light (from infrared to X-ray) into a comprehensive computer catalog of the night sky. They uncovered these new black holes by looking at galaxies which are edge on, so the supermassive black holes at their centre are obscured by a cloud of gas and dust. By comparing between the different wavelengths of light, they were able to spot the new black holes.