3C273, Virgo-A

Set in a rich field of stars and numerous fuzzy galaxies, is the powerful radio source, Virgo-A, also known as 3C273 - object number 273 in the 3rd Cambridge catalogue of radio sources, published in 1959. Indicated by the arrows, it is star-like in appearance, but its powerful radio emission and highly red-shifted spectrum indicated that it was actually the nucleus of a very active and very distant galaxy. 

While distance measures vary, it is at least 2 BILLION light years away and is the brightest known and first object to be identified as a "quasar"; at magnitude 12.9 (variable), it is the most distant object likely visible to the eye and is visible even in small (20 cm-class) telescopes. It is one of the most luminous objects known, the major source of the power being a super-massive black hole of roughly 900 million solar masses residing at the heart of a giant elliptical galaxy.