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The Large Quasar Reference Frame (LQRF). An Optical Representation of the ICRS

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The large number and all-sky distribution of quasars from different surveys, along with their presence in large, deep astrometric catalogs, enables us to build of an optical materialization of the International Celestial Reference System ICRS following its defining principles. Namely that it is kinematically non-rotating with respect to the ensemble of distant extragalactic objects aligned with the mean equator and dynamical equinox of J2000 and realized by a list of adopted coordinates of extragalatic sources. Aims. The Large Quasar Reference Frame LQRF was built with the care of avoiding incorrect matches of its constituents quasars, homogenizing the astrometry from the different catalogs and lists in which the constituent quasars are gathered, and attaining a milli-arcsec global alignment with the International Celestial Reference Frame ICRF, as well as typical individual source position accuracies higher than 100 milli-arcsec. The LQRF contains J2000 referred equatorial coordinates, and is complemented by redshift and photometry information from the LQAC. It is designed to be an astrometric frame, but it is also the basis for the GAIA mission initial quasars list, and can be used as a test bench for quasars space distribution and luminosity function studies. The LQRF is meant to be updated when new quasar identifications and newer versions of the astrometric frames used are realized. In the later case, it can itself be used to examine the relations between those frames.

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  • Astronomy

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