Meeting the LQAC

A.H. Andrei1,2, J. Souchay3, C. Barache3, S. Bouquillon3, D. Suchet3, M. Baudin3, 
A.M. Gontier3, S.Lambert2, C. LePoncin-Lafitte3, F. Taris3, and F.E. Arias5

1 Observatório Nacional/MCT, Brasil
2 Observatório do Valongo, Brasil
3 Observatoire de Paris, SYRTE/CNRS UMR8630, France
4 Royal Observatory of Belgium, Belgium
5 B.I.P.M., France

Oral presentation

The LQAC (Large Quasar Astrometric Catalogue, Souchay et al., A&A 2009) is a compilation of astrometric position as well as physical information at optical and radio wavelengths for 113,666 quasars. Due to its aim of completeness in what concerns objects with reliable astrometry plus the ready available information and further references it is a valuable companion for observational, statistical and theoretical studies of quasars. Here we highlight three such investigations made during the development of the LQAC.
1- Double objects. The combination of astrometric and redshift accuracy enables to assess the rate of doubles and binary pairs in the densest LQAC regions, and to estimate the number of missing or faint objects in the less surveyed regions.
2- Mapping the color loci. As the LQAC contains up to 7 indications of magnitude for each object, and the range of redshift extends to 2.5 for a statistically large population, the effects of reddening can be traced for samples 10 times larger than on prior investigations.
3- Radio loud quasars. The population of radio loud quasars can be traced as belonging to particular loci in the color/color diagrams. This opens interesting venues on the physical models for these objects, at the same that suggests additional criteria to survey them.