3C 273
Observation

3C 273 is visible from March to July in both the northern and southern hemispheres. Situated in the Virgo constellation, it is bright enough to be observed by eye with a 6-inch (150 mm) amateur telescope. Due in part to its radio luminosity and its discovery as the first identified quasar, 3C 273's right ascension in the Fifth Fundamental Catalog (FK5) is used to standardize the positions of 23 extragalactic radio sources used to define the International Celestial Reference System (ICRS).

Given its distance from Earth and visual magnitude, 3C 273 is the most distant celestial object average amateur astronomers are likely to see through their telescopes.
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