The Circinus Galaxy is a Type II Seyfert galaxy and is one of the closest known active galaxies to the Milky Way, though it is probably slightly further away than Centaurus A.
The two main arguments were: (1) The quasar spectrum reveals it to be a narrow-line Seyfert 1 galaxy.
Markarian 231 (UGC 8058) is a Type-1 Seyfert galaxy that was discovered in 1969 as part of a search of galaxies with strong ultraviolet radiation.
NGC 4698 is classified as a Seyfert-2 galaxy with an active galactic nucleus, which displays a prominent emission of radio and X-ray energy from the core while showing narrow emission lines in the optical spectrum.
The comparatively small mass of this black hole, along with the low luminosity of the radio and infrared emission lines, imply that the Milky Way is not a Seyfert galaxy.
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