Radio galaxy in the constellation Cassiopeia
3C 20 is a radio galaxy located in the constellation Cassiopeia. It is one of largest known galaxies with a diameter of . The galaxy features a prominent double hotspot in its eastern lobe. An unusually low fraction of the flux lies within the radio core, which is suggested to be caused by a combination of factors, including jet orientation, synchrotron self-absorption and aging, as well as interactions with surrounding gas and dust.
References.
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Notes.
 ;indicator name="01-sky-coordinates" ; ;templatestyles src="Template:Sky/styles.css" / ;Coordinates: &amp;zoom=&amp;show_grid=1&amp;show_constellation_lines=1&amp;show_constellation_boundaries=1&amp;show_const_names=1&amp;show_galaxies=1&amp;img_source=IMG_all 00h 43m 09.21s, +52° 03′ 33.5″ ;/indicator ;