© 2015. The Korean Astronomical Society. All rights reserved. We present our efforts for extending the simultaneous multi-frequency receiver system of the Korean Very Long Baseline Interferometry (VLBI) Network (KVN) to global baselines in order to measure the frequency-dependent position shifts in Active Galactic Nuclei (AGN) jets, the so called core shift effect, with an unprecedented accuracy (a few micro-arcseconds). Millimeter VLBI observations with simultaneous multi-frequency receiver systems, like those of the KVN, enable us to explore the innermost regions of AGN and high precision astrometry. Such a system is capable of locating the frequency dependent opacity changes accurately. We have conducted the feasibility test-observations with the interested partners by implementing the KVN-compatible systems. Here we describe the science case for measuring the core shift effect in the AGN jet and report progress and future plans on extending the simultaneous multi-frequency system to global baselines.
Jung, T., Dodson, R., Han, S. T., Rioja Capellan, M., Byun, D. Y., Honma, M., Stevens, J., De Vicente, P., & Sohn, B. W. (2015). Measuring the core shift effect in AGN jets with the extended Korean VLBI network. Journal of the Korean Astronomical Society, 48(5), 277-284. https://doi.org/10.5303/JKAS.2015.48.5.277