720 XTF Search Results (expand=subject;f1-spectral-Type=X-ray;f2-subject=Cygnus X-1;f3-subject=Compact Object);f1-spectral-Type%3DX-ray;f2-subject%3DCygnus%20X-1;f3-subject%3DCompact%20Object Results for your query: expand=subject;f1-spectral-Type=X-ray;f2-subject=Cygnus X-1;f3-subject=Compact Object Thu, 01 Jan 1970 12:00:00 GMT The First Black Hole. Since its discovery in 1962, the X-ray binary star Cygnus X-1 has been one of the most intensively studied cosmic X-ray sources. About a decade after its discovery, Cygnus X-1 secured a place in the history of astronomy when a combination of space-based, X-ray observations by the Chandra X-ray Observatory and optical, ground-based observations by the Digitized Sky Survey led to the conclusion that it was a black hole, the first such identification. This is a Chandra X-ray image of Cygnus X-1. Thu, 01 Jan 1970 12:00:00 GMT