[G01-P] Poster

[G01-P-03] Investigations on scale factor from VLBI observations

^○Hana Krasna¹, Oleg Titov², Igor Surkis³, Dmitrii Ivanov³, Alexey Melnikov³ (1.TU Wien, Vienna, Austria, 2.Geoscience Australia, Canberra, Australia, 3.Institute of Applied Astronomy, St. Petersburg, Russia)

The direct connection between the terrestrial and celestial reference frame as it is provided by the Very Long Baseline Interferometry (VLBI) technique makes possible to gain an insight into astrophysical and cosmological studies. One of potentially informative cosmology-oriented evaluation of VLBI astrometric surveys is based on the analysis of the scaling factor that is derived as a partial derivative of the observed group delay to the theoretical geometrical delay. If the observations would perfectly match the theoretical prediction, the scaling factor would be equivalent to unity. Otherwise, some deviation from unity can be detected. Our estimates from two independent software packages OCCAM and VieVS show that the scale factor from the VLBI measurements estimated for each radio source individually discloses a clear systematic aligned with the direction to the Galactic center-anticentre. Therefore, the radio sources located near Galactic anticentre may cause a strong systematic effect on the terrestrial reference frame, especially, in early VLBI years. Furthermore, we investigate a potential dependence of the scaling factor on the radio source redshift. We analyse geodetic VLBI observations carried out within the routine International VLBI Service (IVS) activity extended by selected sessions of the KVAZAR network.