Radio galaxies and radio-loud quasars have been widely used, particularly in the 80s and 90s, to find distant galaxies: by selecting based on radio spectrum and then observing the host galaxy it was possible to find objects at high redshift at modest cost in telescope time.
As radiogalaxias e quásares radio-intensos foron moi utilizados, especialmente nas décadas de 1980 e 1990, para encontrar galaxias distantes: facendo unha selección baseada no espectro de radio e despois observando a galaxia hospedadora era posible encontrar obxectos a altos desprazamentos ao vermello a baixo custo en canto a tempo de telescopio.