Cygnus A (i.e., 3C 405 or QSO B1957+405) is a radio galaxy,
one of the first identified. As a radio source, it was discovered
by Grote Reber in 1938, with his back-yard radio telescope, the
first radio receiver built for that purpose. An apparent
quasar was discovered within it in the 1990s: this is no mystery
since quasars are interpreted as active galactic nuclei (AGNs), which are also often
the driver for strong radio emission from galaxies. Cygnus
A demonstrates the involvement of jets in creating a radio
galaxy's radio emission; its strongest radio signal comes from two
regions in opposite directions from the galaxy itself.