A Radio Galaxy (RG) is a Galaxy emitting a lot of Radio Electromagnetic Radiation (EMR) (Radio-Loud). They have been found with as much as 1039 watts of power in the radio spectrum. Distant radio galaxies are useful as they are relatively easily observed.
A Radio Galaxy is generally an Active Galaxy. Quasars (QSO) and Blazars with a similar radio spectrum are called Radio-Loud Quasars and Radio-Loud Blazars and are assumed to be more distant radio-loud Radio Galaxies.
Cosmic Gamma Ray Background (CGB)
Green Bank 6-cm Radio Source Catalog (GB6)
Parkes Catalog (PKS)
Parkes-MIT-NRAO Surveys (PMN)
RASS/Green Bank Catalog (RGB)