Source structure and position stability of celestial reference frame sources in the Deep South
Abstract
Very long baseline interferometric (VLBI) observations in the Southern Hemisphere have always been more difficult than in the north, and in the past, there have been no dedicated imaging observations of celestial reference frame (CRF) sources at declinations below ~$45^{\circ}$ south. In 2013, we started an imaging campaign to map, monitor and study the structure of southern CRF sources using data from routine astrometric observations in the south. These observations are coordinated through the IVS as part of the Celestial Reference Frame (CRF) and Celestial Reference Frame Deep South (CRDS) sessions. In 2018, we increased the data rate (and thus sensitivity) of the CRF and CRDS sessions to allow for more and weaker sources to be observed. We also optimised the scheduling for improved uv-coverage for imaging. To date, we have imaged 164 sources from 10 CRDS sessions. For 110 of these sources, we produced the first-ever high-resolution images at both 2.3 and 8.4 GHz. We now have multi-epoch images for 96 sources allowing us to study the structural variability over time. We present the most recent results from our imaging campaign, in particular from recent CRDS that included for the first time also the O'Higgins antenna in Antarctica. We also present an analysis of the source astrometric positions estimated from the CRDS sessions in the prospect of assessing the link between individual astrometric variation and structure changes.
- Publication:
-
25th European VLBI Group for Geodesy and Astrometry Working Meeting
- Pub Date:
- March 2021
- Bibcode:
- 2021evga.confP...7B
- Keywords:
-
- Geodesy;
- Astrometry;
- Celestial reference frame;
- VLBI;
- Source structure;
- Quasars