Riccardo Giacconi et al, “Evidence for X-Rays From Sources Outside the Solar System”, in Physical Review Letters, 9 No. 11 pp. 439–443, December 1, 1962. Original wrappers. Fine copy. $300
“Giacconi (b. 1931) announced the discovery of X-rays emissions from the Scorpius constellation thousands of times as energetic as its emissions in the visible spectrum – the first cosmic X-ray source…thus putting (x-ray astronomy) on the map”–David Wenner, The History of Physics Collection, entry on X-Ray Astronomy.
Giacconi shared the 2002 Nobel prize in Physics “for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources.”