A survey has revealed hundreds of previously unidentified black holes using data from the Chandra Source Catalog and the Sloan Digitized Sky Survey (SDSS). Researchers compared the X-ray and optical data for a class of objects known as “XBONGs” (X-ray bright, optically normal galaxies) to reveal about 400 supermassive black holes. These graphics show these XBONGs in X-rays from Chandra and optical light from SDSS. This result helps explain some unusual properties of XBONGs as well as provide a more accurate census of supermassive black holes that exist in the centers of most large galaxies.