Einstein Observatory

Einstein Observatory (HEAO-2) was the first fully imaging X-ray telescope put into space and the second of NASA's three High Energy Astrophysical Observatories. The observatory was named in honor of Albert Einstein.

Performance
Launched in 1978, it was several hundred times more sensitive than any previous X-ray mission. Einstein provided X-ray astronomers with the capability to image extended objects, diffuse emission, and to detect faint sources. It had an angular resolution in arcseconds and a field of view of tens of arcminutes.