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We have a project to measure magnetic fields in the obscuring tori of AGNs. We observed five free-free absorbed jets in radio galaxies with polarimetric VLBI at 15 GHz to determine Faraday rotation measures. Surprisingly, all sources are…

Astrophysics · Physics 2007-05-23 E. Middelberg

We present a milliarcsecond-resolution radio survey of 17 high-redshift (4 < z < 5.4) blazar candidates observed with the European Very Long Baseline Interferometry (VLBI) Network at 5 GHz. The primary objective of this study was to…

The AuScope geodetic Very Long Baseline Interferometry array consists of three new 12 m radio telescopes and a correlation facility in Australia. The telescopes at Hobart (Tasmania), Katherine (Northern Territory) and Yarragadee (Western…

I review observational properties of low power radio loud AGN. High resolution VLBI observations allow the estimate of the jet velocity and orientation with respect to the line of sight and the determination of the Doppler factor. These…

Astrophysics · Physics 2009-04-14 G. Giovannini , M. Giroletti

The paper presents the results of the largest to date VLBI absolute astrometry campaign of observations of 13,645 radio sources with the Very Long Baseline Array (VLBA). Of them, 7220 have been detected, including 6755 target sources that…

Instrumentation and Methods for Astrophysics · Physics 2020-12-16 Leonid Petrov

Young and magnetically active low-mass stars often exhibit non-thermal coronal radio emission due to the gyration of electrons in their magnetized chromospheres. This emission is easily detectable at centimeter wavelengths with the current…

Solar and Stellar Astrophysics · Physics 2022-06-01 R. Launhardt , L. Loinard , S. A. Dzib , J. Forbrich , G. C. Bower , Th. K. Henning , A. J. Mioduszewski , S. Reffert

Stellar occultations currently provide the most accurate ground-based measurements of the positions of natural satellites (down to a few kilometres for the Galilean moons). However, when using these observations in the calculation of…

Earth and Planetary Astrophysics · Physics 2023-08-09 M. Fayolle , V. Lainey , D. Dirkx , L. I. Gurvits , G. Cimo , S. J. Bolton

We present the results of several multi-station Very Long Baseline Interferometry (VLBI) experiments conducted with the ESA spacecraft Venus Express as a target. To determine the true capabilities of VLBI tracking for future planetary…

Instrumentation and Methods for Astrophysics · Physics 2012-05-15 Dmitry A. Duev , Guifre Molera Calves , Sergei V. Pogrebenko , Leonid I. Gurvits , Giuseppe Cimo , Tatiana Bocanegra Bahamon

For Very Long Baseline Interferometry (VLBI), the fringe spacing is extremely narrow compared to the field of view imposed by the primary beam of each element. This means that an extremely large number of resolution units can potentially be…

Instrumentation and Methods for Astrophysics · Physics 2013-02-26 John S. Morgan , F. Mantovani , A. T. Deller , W. Brisken , W. Alef , E. Middelberg , M. Nanni , S. J. Tingay

The VLBA was used at 1.6 GHz to observe a target field 50 arcminutes in diameter including the core of M31. Novel VLBI correlation techniques were used to observe 200 sources simultaneously, of which 16 were detected. We classify all 16 as…

We present the results of a survey of radio continuum sources near the Galactic plane using the Very Long Baseline Array (VLBA). Our observations are designed to identify compact extragalactic sources of milliarcsecond size that can be used…

Astrophysics of Galaxies · Physics 2015-05-27 K. Immer , A. Brunthaler , M. J. Reid , A. Bartkiewicz , Y. K. Choi , K. M. Menten , L. Moscadelli , A. Sanna , Y. W. Wu , Y. Xu , B. Zhang , X. W. Zheng

We present here a concept of measuring local ties between collocated GNSS and VLBI stations using the microwave technique that effectively transforms a GNSS receiver to an element of a VLBI network. This is achieved by modifying the signal…

Based on published data, we have assembled a sample of 126 radio stars with the trigonometric parallaxes and proper motions measured by VLBI and available in the Gaia DR3 catalogue (in fact, Gaia EDR3). Our analysis of the Gaia--VLBI proper…

Astrophysics of Galaxies · Physics 2023-05-16 Vadim V. Bobylev

The very long baseline interferometry (VLBI) technique offers angular resolutions superior to any other instruments at other wavelengths, enabling unique science applications of high-resolution imaging of radio sources and high-precision…

Instrumentation and Methods for Astrophysics · Physics 2018-02-06 T. An , B. W. Sohn , H. Imai

From Very Long Baseline Array (VLBA) observations we previously identified a population of 123 young stellar systems with nonthermal radio emission toward the core of the Orion Nebula Cluster (ONC). We find optical sources in the Gaia DR2…

Solar and Stellar Astrophysics · Physics 2021-01-13 Sergio A. Dzib , Jan Forbrich , Mark J. Reid , Karl M. Menten

The data release 1 (DR1) of milliarcsecond-scale accurate optical positions of stars and galaxies was recently published by the space mission Gaia. We study the offsets of highly accurate absolute radio (very long baseline interferometry,…

Astrophysics of Galaxies · Physics 2017-02-01 Y. Y. Kovalev , L. Petrov , A. V. Plavin

We present the results of a second epoch of 18cm global Very Long-Baseline Interferometry (VLBI) observations, taken on 23 February 2001, of the central kiloparsec of the nearby starburst galaxy Messier 82. These observations further…

Studies of Galactic HII regions are of crucial importance for studying star formation and the evolution of the interstellar medium. Gaining an insight into their physical characteristics contributes to a more comprehensive understanding of…

Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of the relativistic…

Astrophysics of Galaxies · Physics 2016-08-03 Sang-Sung Lee , Andrei P. Lobanov , Thomas P. Krichbaum , J. Anton Zensus

Astrometric Very Long Baseline Interferometry (VLBI) observations of maser sources in the Milky Way are used to map the spiral structure of our Galaxy and to determine fundamental parameters such as the rotation velocity ($\Theta_0$) and…

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