These images show an object that astronomers think could be an intermediate-mass black hole (IMBH), a rare class of black holes. Called NGC 6099 HLX-1, and labeled in one of the images above, this black hole seems to reside in a compact star cluster in a giant elliptical galaxy. In the images, optical light data from NASA’s Hubble Space Telescope are shown with X-rays from NASA’s Chandra X-ray Observatory. NGC 6099 is the elliptical galaxy to the lower left, and a companion elliptical galaxy (NGC 6098) is located in the upper right.