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Since 2011 Ventspils International Radio Astronomy Centre has been involved in the large scale infrastructure project which allowed significant speeding-up of the upgrading activities related to radio telescopes RT-32 and RT-16 as to its…

Instrumentation and Methods for Astrophysics · Physics 2020-08-14 Vladislavs Bezrukovs , Marcis Bleiders , Arturs Orbidans , Dmitrijs Bezrukovs

Positions and maps of 1608 new compact sources were obtained in twelve sessions observed during 1994--2002 at the VLBA network at 8.4/2.3 GHz. These sources are recommended for use as calibrators for phase reference imaging and as geodetic…

Astrophysics · Physics 2007-05-23 Leonid Petrov , David Grodon , Anthony Beasley , Ed Fomalont

This white paper describes the science case for Very Long Baseline Interferometry (VLBI) and provides suggestions towards upgrade paths for the European VLBI Network (EVN). The EVN is a distributed long-baseline radio interferometric array,…

Very Long Baseline Interferometry, or VLBI, is the observing technique yielding the highest-resolution images today. Whilst a traditionally large fraction of VLBI observations is concentrating on Active Galactic Nuclei, the number of…

Astrophysics · Physics 2009-06-23 Enno Middelberg , Uwe Bach

The Long Wavelength Array (LWA) will be a new multi-purpose radio telescope operating in the frequency range 10-88 MHz. Scientific programs include pulsars, supernova remnants, general transient searches, radio recombination lines, solar…

Instrumentation and Methods for Astrophysics · Physics 2012-06-11 G. B. Taylor , The LWA Collaboration

The ngVLA is a new interferometric radio astronomy facility with transformative capabilities, being developed by the National Radio Astronomy Observatory. It combines two orders of magnitude in frequency coverage, over 1.2 - 116 GHz, with…

Instrumentation and Methods for Astrophysics · Physics 2025-04-22 T. K. Sridharan , S. Bhatnagar , P. Jagannathan , K. Golap

We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the double-image gravitational lens JVAS B0218+357, made to establish the precise registration of the A and B lensed image positions. The…

Astrophysics · Physics 2009-11-11 Rupal Mittal , Richard Porcas , Olaf Wucknitz , Andy Biggs , Ian Browne

The Very Long Baseline Interferometry (VLBI) monitoring program TANAMI provides bi-monthly, dualfrequency (8GHz and 22GHz) observations of extragalactic jets with milliarcsecond resolution south of -30 deg declination using the Australian…

High Energy Astrophysical Phenomena · Physics 2012-05-08 Cornelia Müller , M. Böck , J. Wilms , M. Kadler , R. Ojha , J. Blanchard , M. Dutka , E. Ros

We present the results of simultaneous multi-frequency imaging observations at 22, 43, 86, and 129\,GHz of OJ\,287. We used the Korean VLBI Network as part of the Interferometric MOnitoring of GAmma-ray Bright active galactic nuclei…

Observations of gamma-ray bursts (GRBs) at Very High Energy (VHE) offer a unique opportunity to investigate particle acceleration processes, magnetic fields and radiation fields in these events. Very Long Baseline Interferometry (VLBI)…

In April 2002 an array of antennas operating at 129GHz successfully detected VLBI fringes on both continuum AGN and SiO maser sources. The 129GHz fringes on maser sources represent the highest frequency spectral line VLBI detections to…

The alignment between the radio-based International Celestial Reference Frame (ICRF) and the optical Gaia Celestial Reference Frame (Gaia-CRF) is critical for multi-waveband astronomy, yet systematic offsets at the optical bright end (G<13)…

Global VLBI imaging at millimeter and sub-millimeter wavelength overcomes the opacity barrier of synchrotron self-absorption in AGN and opens the direct view into sub-pc scale regions not accessible before. Since AGN variability is more…

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

This paper presents the catalog of correlated flux densities in three ranges of baseline projection lengths of 637 sources from a 43 GHz (Q-band) survey observed with the Korean VLBI Network. Of them, 623 sources have not been observed…

The capabilities of the Global mm-VLBI Array are summarized and demonstrated through actual images from our monitoring of extragalactic radio jets. This sensitive 3mm-VLBI interferometer is able to provide images of up to 50 microarcseconds…

We present the results of a spectral analysis using simultaneous multifrequency (22, 43, 86, and 129 GHz) very long baseline interferometry (VLBI) observations of the Korean VLBI Network (KVN) on BL Lac object, Markarian 421 (Mrk 421). The…

High Energy Astrophysical Phenomena · Physics 2024-02-20 Jee Won Lee , Sang-Sung Lee , Jeffrey Hodgson , Algaba Juan-Carlos , Sang-Hyun Kim , Whee Yeon Cheong , Hyeon-Woo Jeong , Sincheol Kang

We present preliminary results from a VLBI survey at $\lambda=6 $cm of a sample of 35 sources with flux densities of 2 - 100 mJy. These sources were selected from the VLA FIRST survey at $\lambda = 20 $cm, in a 3 degree field around the…

Astrophysics · Physics 2009-10-31 S. T. Garrington , M. A. Garrett , A. Polatidis

In this paper, we conduct a multi-frequency analysis of the gamma-ray bright blazar 1308+326 from February 2013 to March 2020, using the Korean VLBI Network at 22 and 43 GHz and gamma-ray data from the Fermi Large Area Telescope (LAT). Our…

High Energy Astrophysical Phenomena · Physics 2024-04-12 Shan Li , Sang-Sung Lee , Whee Yeon Cheong

Millimeter-VLBI images probe as deep as never before the nuclei of AGN. Global 3mm-VLBI where the VLBA is combined with sensitive European stations, gives CLEAN maps of a quality, which never before was so good. VLBI at 147 GHz yields…

Astrophysics · Physics 2007-05-23 T. P. Krichbaum , D. A. Graham , A. Witzel , J. A. Zensus , A. Greve , H. Ungerechts , M. Grewing