X-ray background
The observed X-ray background is thought to result from, below 0.3 keV, galactic X-ray emission, the galactic X-ray background, and, above 0.3 keV, from a combination of numerous X-ray point sources outside of the Milky Way, the cosmic X-ray background (CXB, XRB, CXRB). == History == In 1962, in a project led by Riccardo Giacconi, Herbert Gursky, Frank R. Paolini, and Bruno B. Rossi, Geiger counters mounted on a rocket detected a "diffuse background radiation" of X-ray flux spanning all directions covered by the rocket's rotation.