A robust derivation of the tight relationship of radio core dominance to
  inclination angle in high redshift 3CRR sources
  It is believed that, in radio-loud active galactic nuclei (AGN), the core
radio flux density can be normalized to the flux density of the extended lobe
emission to infer the orientation of a radio source. However very little is
known about the reliability and precision of this method, and we are unaware of
any robust conversion recipe to infer the inclination from the core dominance.
Investigating whether or not the radio core dominance parameter R separates the
quasars from the radio-galaxies in the $z \ge$~1 3CRR catalog, we found
excellent agreement of R with optical type, infrared flux ratios and optical
polarization. This indicates that probably both R and optical classification
are very good orientation indicators, and the unified model is strongly
predictive for these objects. The relative number densities indicate
half-opening angles close to 60$^\circ$, as expected from large surveys. The
separations of optical types according to radio core dominance as well as
NIR/MIR ratios, which are essentially perfect, means that there can be only a
small dispersion of torus half-opening angles. Also, even though torus dust is
thought to be clumpy, there is an almost zero probability to see a type-1
source at high inclination. Finally, using only the Copernican Principle, i,e,
the assumption that solid angle is filled uniformly with source axis
orientations, we estimated a semi-empirical relation between core dominance and
AGN inclination. This makes it possible to use R to infer the inclination of a
source to an accuracy of $\sim$ 10 degrees or less, at least for this type of
object.
