Probing the Properties of Gaia-CRF2 Quasars at the Faintest Magnitudes

Abstract Gaia data release 2 (DR2) provides the best non-rotating optical frame aligned with radio (ICRF) thanks to inclusion of about half-million quasars in five-parameter astrometric solution. We cross-match DR2 from Large Quasar Astrometric Catalogue, Sloan Digital Sky Survey and LAMOST, obtaining 208,743 new sources (denominated as KQCG), most them are fainter than G = 19. Given their crucial diagnostic role for characterizing properties celestial reference frame, we aim probe more accurately at faintest magnitudes. Combining already identified DR2, estimate moving mean parallaxes proper motions. The features motion analyzed by means vectorial spherical harmonics; scalar field is expanded into harmonics investigate spatial correlation, which reveals an angular scale systematics ≈18° a rms amplitude 13 μ as. global motions calculated. bias can be up ∼10 yr −1 some sky regions both components, these biases seem related patterns scanning law. exhibits (−6, −5, −5) ± 1 spin northern hemisphere (0, +1, +3) southern one, may caused star contamination. quadrupolar anisotropy filed analyzed, where significant signal (the largest component’s −15 ) found.