3:30 PM - 4:30 PM
[G01-P-14] Assessment of the impact of session types, observation time span, network geometry and -size on the estimation of radio source coordinates
A distinctive feature of VLBI (very long baseline interferometry) is the evolution of stations and station networks, as well as the advances in technology throughout its observing history. Several authors have assessed systematics in VLBI-derived EOP (Earth Orientation Parameters) time series depending on the involved station networks. However, how changes of terrestrial networks changes the source position and consequently the CRF (Celestial Reference Frame) still needs to be investigated. The IAG Working Groups associated with IAG Sub-Commission 1.4 on “Interaction of Celestial and Terrestrial Reference Frames" is investigating this effect.
Furthermore, there is an ongoing discussion concerning the inclusion of observations obtained during the early years of geodetic VLBI, 1979-1990. Some colleagues suggest to completely omit these data, allegedly to avoid any potential contamination due to the poorer quality of these sessions, be it in terms of network geometry and scheduling, or because of the lower observation density and data recording rate. Usually also the so-called ‘intensive' sessions with an duration of one hour only are not included in reference frame determinations.
Within this work we will assess the impact of such choice of data on the radio source positions in terms of time series and global positions. We will evaluate the quality of the results with respect to session types, which is inevitably connected to specific station networks, thus network volumes, and radio sources. Finally, we will compare our results against a solution that aims at the completeness of geodetic VLBI data, containing the entire IVS VLBI data base including the 'intensives', and also all the available sessions from the Russian Quasar network.
Furthermore, there is an ongoing discussion concerning the inclusion of observations obtained during the early years of geodetic VLBI, 1979-1990. Some colleagues suggest to completely omit these data, allegedly to avoid any potential contamination due to the poorer quality of these sessions, be it in terms of network geometry and scheduling, or because of the lower observation density and data recording rate. Usually also the so-called ‘intensive' sessions with an duration of one hour only are not included in reference frame determinations.
Within this work we will assess the impact of such choice of data on the radio source positions in terms of time series and global positions. We will evaluate the quality of the results with respect to session types, which is inevitably connected to specific station networks, thus network volumes, and radio sources. Finally, we will compare our results against a solution that aims at the completeness of geodetic VLBI data, containing the entire IVS VLBI data base including the 'intensives', and also all the available sessions from the Russian Quasar network.