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Millimetre-VLBI is an important tool in AGN astrophysics, but it is limited by short atmospheric coherence times and poor receiver and antenna performance. We demonstrate a new kind of phase referencing for the VLBA, enabling us to increase…

Astrophysics · Physics 2007-05-23 E. Middelberg , A. L. Roy , R. C. Walker , H. Falcke , T. P. Krichbaum

The space astrometry mission GAIA will construct a dense optical QSO-based celestial reference frame. For consistency between the optical and radio positions, it will be important to align the GAIA frame and the International Celestial…

Astrophysics · Physics 2008-12-18 G. Bourda , P. Charlot , R. Porcas , S. Garrington

Radio observations using the Very Long Baseline Interferometry (VLBI) technique typically have fields of view of only a few arcseconds, due to the computational problems inherent in imaging larger fields. Furthermore, sensitivity…

Instrumentation and Methods for Astrophysics · Physics 2012-07-06 E. Middelberg , A. T. Deller , W. F. Brisken , J. S. Morgan , R. P. Norris

It is anticipated that future space-born missions, such as Gaia, will be able to determine in optical domain positions of more than 100,000 bright quasars with sub-mas accuracies that are comparable to very long baseline interferometry…

Instrumentation and Methods for Astrophysics · Physics 2013-06-13 Leonid Petrov

Dual active galactic nuclei (DAGN) and supermassive black hole binaries (SMBHBs) at kpc and pc-scale separations, respectively, are expected during stages of galaxy merger and evolution. Their observational identification can address a…

Astrophysics of Galaxies · Physics 2018-10-10 Tao An , P. Mohan , Sandor Frey

PSR J0218$+$4232 is a millisecond pulsar (MSP) with a flux density $\sim$ 0.9 mJy at 1.4 GHz. It is very bright in the high-energy X-ray and $\gamma$-ray domains. We conducted an astrometric program using the European VLBI Network (EVN) at…

Solar and Stellar Astrophysics · Physics 2014-02-12 Yuanjie Du , Jun Yang , Robert M. Campbell , Gemma Janssen , Ben Stappers , Ding Chen

I review here the present observational efforts to study parsec-scale radio jets in active galactic nuclei with very-long-baseline interferometry (VLBI) as related to the new window to the Universe opened by the LAT instrument on-board the…

High Energy Astrophysical Phenomena · Physics 2012-05-07 Eduardo Ros

We demonstrate the blind interferometric detection and localization of two fast radio bursts (FRBs) with 2- and 25-arcsecond precision on the 400-m baseline between the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and the CHIME…

Very long baseline interferometry (VLBI) makes it possible to recover images of astronomical sources with extremely high angular resolution. Most recently, the Event Horizon Telescope (EHT) has extended VLBI to short millimeter wavelengths…

Instrumentation and Methods for Astrophysics · Physics 2018-02-05 Katherine L. Bouman , Michael D. Johnson , Adrian V. Dalca , Andrew A. Chael , Freek Roelofs , Sheperd S. Doeleman , William T. Freeman

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)…

Instrumentation and Methods for Astrophysics · Physics 2009-10-08 Richard Dodson , Maria J. Rioja

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two…

Earth and Planetary Astrophysics · Physics 2016-07-27 Paul A. Dalba , Philip S. Muirhead

There are approximately 250 quasars discovered at redshift $z\geq6$, of which only a handful were detected in radio bands, and even fewer were imaged with the highest resolution very long baseline interferometry (VLBI) technique. Here we…

Very-long-baseline interferometry (VLBI) is a challenging observational technique, which requires in-depth knowledge about radio telescope instrumentation, interferometry, and the handling of noisy data. The reduction of the raw data is…

Instrumentation and Methods for Astrophysics · Physics 2022-09-14 Michael Janssen , Jack F. Radcliffe , Jan Wagner

Previous Very Long Baseline Interferometry (VLBI) observations of the quasar B1152+199 at 5GHz has revealed two images of a strongly lensed jet with seemingly discordant morphologies. Whereas the jet appears straight in one of the images,…

Astrophysics of Galaxies · Physics 2020-01-08 Saghar Asadi , Erik Zackrisson , Eskil Varenius , Emily Freeland , John Conway , Kaj Wiik

We report multi-epoch Very Long Baseline Interferometry (VLBI) study of the innermost jet of 3C 84. We carried out 14-epoch VLBI observations during 2006-2009 with the Japanese VLBI Network (JVN) and the VLBI Exploration of Radio Astrometry…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-14 H. Nagai , K. Suzuki , K. Asada , M. Kino , S. Kameno , A. Doi , M. Inoue , U. Bach

We present simulated images of Supernova 1993J at 8.4 GHz using Very Long Baseline Interferometry (VLBI) techniques. A spherically symmetric source model is convolved with realistic uv-plane distributions, together with standard imaging…

The extraordinary astrometric accuracy of radio interferometry creates an important and unique opportunity for the discovery and characterization of exo-planets. Currently, the Very Long Baseline Array can routinely achieve better than 100…

Astrophysics · Physics 2007-05-23 Geoffrey C. Bower , Alberto Bolatto , Eric Ford , Paul Kalas , Jim Ulvestad

We apply an efficient selection method to identify potential weak Very Long Baseline Interferometry (VLBI) target quasars simply using optical (SDSS) and low-resolution radio (FIRST) catalogue data. Our search is restricted to within 12"…

Astrophysics · Physics 2015-05-13 S. Frey , K. E. Gabanyi , Y. Asaki

Context: The Deep Extragalactic VLBI-Optical Survey (DEVOS) aims at constructing a large sample of compact radio sources up to two orders of magnitude fainter than those studied in other Very Long Baseline Interferometry (VLBI) surveys.…

Astrophysics · Physics 2008-01-09 S. Frey , L. I. Gurvits , Z. Paragi , L. Mosoni , M. A. Garrett , S. T. Garrington

We present high-resolution radio interferometric imaging observations of the radio source NVSS J182659+343113 (hereafter J1826+3431), the proposed radio counterpart of the ${\gamma}$-ray source, 3EG J1824+3441 detected by the Energetic…

Astrophysics of Galaxies · Physics 2020-09-16 Patrik Milán Veres , Krisztina Éva Gabányi , Sándor Frey
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