- Reminders
- Electromagnetic Spectrum
- Multi Wavelength Milky Way
- Active Galaxies: Radio Loud
- 1918: H. Curtis, 1954: W. Baade and R. Minkowski, 1959: L. Woltjer, 1963: M. Schmidt, FR 1, FR 2
- Active Galaxies: Radio Quiet
- 1943: C. Seyfert, Seyfert 2
- Active Galaxies: Unification
- Unification
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