Abstract
Results from the Finnish quasar monitoring program are discussed. Both the spectra and the radio variability indicate that both the basic structure and the mechanism for variability are the same for all AGN. The basic radio properties of low and high polarization quasars are in agreement with orientation-dependent scenarios. The contradictory properties of BL Lac objects can be understood if they in reality consist of two physically different classes. One class, consisting of highly boosted, strongly variable, distant BL Lacs with quasarlike spectra, represents the extreme end of the FR II - LPQ - HPQ population; sources aligned to a few degrees with our line of sight. The other BL Lac population consists of much less boosted, moderately variable, nearby FR I radio galaxies beamed towards us.
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© 1991 Springer-Verlag
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Valtaoja, E. (1991). Variability of BL Lac objects in the radio regime. In: Duschl, W.J., Wagner, S.J., Camenzind, M. (eds) Variability of Active Galaxies. Lecture Notes in Physics, vol 377. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0030051
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DOI: https://doi.org/10.1007/BFb0030051
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