Related papers: Using radio stars to link the Gaia and VLBI refere…
With the publication of Gaia DR2, 1.3 billion stars now have public parallax and proper motion measurements. In this contribution, we compare the results for sources that have both optical and radio measurements, focusing on circumstellar…
Summarizes current status of radio interferometry at radio frequencies between Earth-based receivers, for astrometric and geodetic applications. Emphasizes theoretical models of VLBI observables that are required to extract results at the…
We performed an automated comparison of the FIRST radio survey with the APM optical catalog to find radio lobes with optical counterparts. Based on an initial survey covering ~3000 square degrees, we selected a sample of 33 lens candidates…
We report on optically selected stellar candidates of SARAO MeerKAT 1.3 GHz radio continuum survey sources of the Galactic plane. Stellar counterparts to radio sources are selected by cross-matching the MeerKAT source positions with…
In this document we layout a new method to achieve "bona fide" high precision Very-Long-Baseline-Interferometry (VLBI) astrometric measurements of frequency-dependent positions of celestial sources (even) in the high (mm-wavelength)…
In this paper, we investigate the relationship between 150MHz luminosity and star formation rate (the SFR-L150 relation) using 150MHz measurements for a near-infrared selected sample of 118,517 $z<1$ galaxies. New radio survey data offer…
We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog. Our full sample contains young stellar objects, evolved AGB stars, pulsars and other radio stars. Excluding AGB stars, which show…
In order to search for new VLBI sources in the Galactic plane that can be used as phase reference sources in differential VLBI, we have conducted 22 GHz observations of radio sources in the Galactic plane using the Japanese VLBI Network…
In this study, we compared results of determination of the orientation angles between celestial reference frames realized by radio source position catalogues using three methods of accounting for correlation information: using the position…
We investigate a phase-reference VLBI observation that was conducted at 15.4 GHz by fast switching VLBA antennas between the compact steep-spectrum radio source 3C 138 and the quasar PKS 0528+134 which are about 4$^\circ$ away on the sky.…
We use four observations with the European VLBI network to measure the first precise radio parallax of the Crab Pulsar. We found two in-beam extragalactic sources just outside the Crab Nebula, with one bright enough to use as a background…
We present a sample of 135,873 RR Lyrae stars (RRLs) with precise photometric-metallicity and distance estimates from our newly calibrated $P-\phi_{31}-R_{21}-$[Fe/H]/$P-R_{21}-$[Fe/H] and $G$ band absolute magnitude-metallicity relations.…
The third realization of the International Celestial Reference Frame (ICRF3) was adopted in August 2018 and includes positions of extragalactic objects at three frequencies: 8.4 GHz, 24 GHz, and 32 GHz. In this paper, we present celestial…
Very long baseline radio interferometry (VLBI) with ground-based observatories is limited by the size of Earth, the geographic distribution of antennas, and the transparency of the atmosphere. In this whitepaper, we present Capella, a…
The second release of Gaia data (Gaia DR2) contains the astrometric parameters for more than half a million quasars. This set defines a kinematically non-rotating reference frame in the optical domain referred to as the Gaia-CRF2. The…
The most precise realization of inertial reference frame in astronomy is the catalogue of 212 defining extragalactic radiosources with coordinates obtained during VLBI observation runs in 1979-1995. IAU decided on the development of the…
We employed the Very Large Array (VLA) of the National Radio Astronomy Observatory in C configuration to map 39 ultraluminous IRAS galaxies at 6~cm and 20~cm, at resolutions of ~ 4" and 15", respectively, and 24 sources at 6~cm with in the…
Grid stars and reference stars provide the fundamental global and local astrometric reference frames for observations by the Space Interferometry Mission. They must therefore be astrometrically stable at the ~1 uas level. I present simple…
The International Celestial Reference Frame (ICRF) plays an important role in astronomy and geodesy. The realization of ICRF is based on the position of thousands of quasars observed using the Very-Long Baseline Interferometry (VLBI)…
It has long been known that luminous, ultra-steep spectrum radio sources are preferentially associated with massive galaxies at high redshifts. Here we describe a pilot project directed at such objects, to demonstrate the feasibility and…