Conclusions

The Parkes quasars can, we conclude, be crudely divided into three populations:

1.

The `Main Sequence': % of the Parkes sources have approximately power-law spectral energy distributions, with spectral indices (

) in the range

. The nature of these sources is discussed by Whiting et al.

2.

Very Red Sources: These sources, which comprise % of the Parkes sample, are characterised by much redder continuum slopes in the optical than in the IR. They tend to have relatively steep radio spectra. Half these sources are radio galaxies, while most of the remainder are highly dust-reddened quasars. The undetected sources are probably high redshift members of this class.

3.

Oddballs: Roughly 2% of the Parkes sample defy this categorisation.

The `main sequence' sources, both red and blue, should be easily detectable in combined near-IR and optical QSO surveys, due to their excess flux in the K and/or B bands.

© Copyright Astronomical Society of Australia 1997