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We have obtained mas-scale resolution very long baseline interferometry (VLBI) images of a sample of Seyfert 1 and Seyfert 2 galaxies at 5 GHz (wavelength, $\lambda$ = 6 cm). The Seyferts of the two types were chosen to be matched in…

Astrophysics · Physics 2009-11-10 Dharam Vir Lal , Prajval Shastri , Denise C. Gabuzda

Adding VLBI capability to the SKA arrays will greatly broaden the science of the SKA, and is feasible within the current specifications. SKA-VLBI can be initially implemented by providing phased-array outputs for SKA1-MID and SKA1-SUR and…

The internet has been used for data transfer in radio astronomy ever since its inception; however it is only recently that network bandwidth capability means that the internet becomes competitive with traditional forms of data storage. Very…

Instrumentation and Methods for Astrophysics · Physics 2014-11-20 R. E. Spencer , R. Hughes-Jones , M. Strong , S. Casey , A. Rushton , P. Burgess , S. Kershaw , C. Greenwood

We demonstrate phase correction of 3 mm VLBI observations using the scanning 18 GHz to 26 GHz water vapour radiometer at Effelsberg and we demonstrate an absolute accuracy of 15 mm in zenith path delay by comparing with GPS and radiosondes.…

Astrophysics · Physics 2007-05-23 A. L. Roy , H. Rottmann , U. Teuber , R. Keller

This paper presents Very Long Baseline Array (VLBA) observations of 13 double-peaked [O III] emission-line type-2 Active Galactic Nuclei (AGNs) at redshifts 0.06 < z < 0.41 (with a median redshift of z~0.15) identified in the Sloan Digital…

Astrophysics of Galaxies · Physics 2018-03-14 Xin Liu , T. Joseph W. Lazio , Yue Shen , Michael A. Strauss

Relativistic bending in the vicinity of a massive body is characterized only by the post-Newtonian parameter $\gamma$ within the standard parameterized post-Newtonian formalism, which is unity in General Relativity. Aiming at estimating…

General Relativity and Quantum Cosmology · Physics 2015-05-13 S. B. Lambert , C. Le Poncin-Lafitte

We demonstrate that at 1.4 GHz the combined response of sources detected serendipitously in deep, wide-field VLBI images is sufficient to permit self-calibration techniques to be employed. This technique of "full-beam" VLBI self-calibration…

Astrophysics · Physics 2007-05-23 M. A. Garrett , J. M. Wrobel , R. Morganti

Radio observations with Very Long Baseline Interferometry (VLBI) provide the highest resolution in astronomy. Combining earth-bound with space-based telescopes and advancing the observations to mm-wavelengths increases the resolution even…

Astrophysics · Physics 2007-05-23 J. A. Zensus , T. P. Krichbaum , S. Britzen

We have obtained 8.4 GHz VLBA observations of a 31-GHz complete sample of ~100 sources between 10 and 100 mJy. The main goals of these observations are: to determine the angular size, radio spectra and identification for a weak sample of…

Astrophysics · Physics 2008-06-19 W. A. Majid , E. B. Fomalont , D. S. Bagri

We discuss the technique of Wide-field imaging as it applies to Very Long Baseline Interferometry (VLBI). In the past VLBI data sets were usually averaged so severely that the field-of-view was typically restricted to regions extending a…

Astrophysics · Physics 2009-10-31 M. A. Garrett , R. W. Porcas , A. Pedlar , T. W. B. Muxlow , S. T. Garrington

To accurately link the radio and optical Celestial Reference Frames (CRFs) at optical bright end, i.e., with Gaia G band magnitude < 13, increasing number and improving sky distribution of radio stars with accurate astrometric parameters…

Solar and Stellar Astrophysics · Physics 2023-05-03 Wen Chen , Bo Zhang , Jingdong Zhang , Jun Yang , Shuangjing Xu , Yan Sun , Xiaofeng Mai , Fengchun Shu , Min Wang

We present the observational results from the 43-GHz Very Long Baseline Array (VLBA) observations of 124 compact radio-loud active galactic nuclei (AGNs) that were conducted between 2014 November and 2016 May. The typical dimensions of the…

High Energy Astrophysical Phenomena · Physics 2020-07-07 X. -P. Cheng , T. An , S. Frey , X. -Y. Hong , X. He , K. I. Kellermann , M. L. Lister , B. -Q. Lao , X. -F. Li , P. Mohan , J. Yang , X. -C. Wu , Z. -L. Zhang , Y. -K. Zhang , W. Zhao

We report preliminary results of a visual inspection of ~4300 deg$^2$ covered by 4414 images of the 3-GHz VLA Sky Survey (VLASS, epoch 1.1) in search of extended radio structures. Over 7600 positions were registered, and for a subset of 270…

Astrophysics of Galaxies · Physics 2018-08-23 Agueda C. Villarreal Hernández , Heinz Andernach

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

I present an overview of important results obtained using high-resolution very long baseline interferometry (VLBI) observations of X-ray binary systems. These results derive from both astrometric observations and resolved imaging of…

Astrophysics · Physics 2009-11-13 James Miller-Jones

Very-long-baseline interferometry (VLBI) at frequencies above 230 GHz with Earth-diameter baselines gives spatial resolution finer than the ${\sim}50 \mu$as "shadow" of the supermassive black hole at the Galactic Center, Sagittarius A* (Sgr…

Instrumentation and Methods for Astrophysics · Physics 2019-08-21 Daniel C. M. Palumbo , Sheperd S. Doeleman , Michael D. Johnson , Katherine L. Bouman , Andrew A. Chael

We observed the pair of radio sources 1150+812 and 1803+784 in November 1993 with a VLBI array, simultaneously recording at 8.4 and 2.3 GHz. We determined the angular separation between the two sources with submilliarcsecond accuracy by…

Astrophysics · Physics 2009-10-31 M. A. Perez-Torres , J. M. Marcaide , J. C. Guirado , E. Ros

Compact galactic and extragalactic radio sources can be imaged with an unsurpassed angular resolution of a few ten micro-arcseconds, adopting the observing technique of global millimeter VLBI. Here we present the Global Millimeter VLBI…

Astrophysics · Physics 2007-05-23 T. P. Krichbaum , I. Agudo , U. Bach , A. Witzel , J. A. Zensus

The Korean very-long-baseline interferometry (VLBI) network (KVN) and VLBI Exploration of Radio Astrometry (VERA) Array (KaVA) is the first international VLBI array dedicated to high-frequency (23 and 43 GHz bands) observations in East…