Exploring different methods to describe source position variations

The positions of the radio sources in the ICRF3 catalog, representing the newest realization of the Celestial Reference Frame (CRF), are given as a time invariant coordinate pair. However, systematic changes of source positions at different spacial and temporal scales are well documented. Failing to acknowledge such source behavior might lead to a deterioration in the quality of the frame, and thus in all derived variables, e.g. the orientation parameters of the Earth (EOP). One approach to overcome these shortcomings is the parametrization of source positions, similar to what is applied to the positions of the station. We present a feasible approach to parameterize all the source positions observed within the IVS data archive and produce a celestial reference frame based thereon, together with a list of consistent defining sources. We compare the resulting frame with the conventional ICRF3 as well as the Gaia frame to uncover eventual deformations and their origin. Further we examine the resulting EOP and station positions and give an evaluation of the precision and accuracy of the parameters