Extending the K-band Celestial Frame Emphasizing Southern Hemisphere

Abstract

K-band radio observations have the potential to form the basis for the most accurate celestial reference frame (CRF) ever constructed. We present a new collaboration to observe southern hemisphere extra-galactic radio sources at 22 GHz (K-band). The aim of this project is to densify the ICRF at that frequency and to provide calibrators for astronomy. Relative to the standard S/X observing bands, at K-band sources are expected to exhibit more compact source morphology and reduced core shift. This reduction of astrophysical systematics should be advantageous in tying the VLBI radio frame to the Gaia optical frame. Initial fringe demonstrations were carried out on 23 August 2013 between telescopes in Australia, Korea and South Africa. The Korea to South Africa baselines will extend Kband CRF coverage down to about −45◦ declination. Observations between Australia and South Africa will extend coverage to the south polar cap and thus gain full sky coverage for the K-band CRF. The second phase of our plan includes more extensive astrometric observations to complete sky coverage at K-band as well as observations using a larger network of telescopes in an effort to image source structure.