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(abridged) Very long baseline interferometry (VLBI) observations at 86$\,$GHz (wavelength, $\lambda = 3\,$mm) reach a resolution of about 50 $\mu$as, probing the collimation and acceleration regions of relativistic outflows in active…

Extending geodetic and astrometric Very Long Baseline Interferometry (VLBI) observations from traditional centimeter wavebands to millimeter wavebands offers numerous scientific potentials and benefits. However, it was considered quite…

We present an all-sky catalog of absolute positions and estimates of correlated flux density of 21,942 compact radio sources determined from processing interferometric visibility data of virtually all very long baseline interferometry…

Instrumentation and Methods for Astrophysics · Physics 2025-01-20 Leonid Petrov , Yuri Y. Kovalev

We present a new technique for obtaining model fittings to VLBI images of astrophysical jets. The method minimizes a performance function proportional to the sum of the squared difference between the model and observed images. The model…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Anderson Caproni , Hektor Monteiro , Zulema Abraham , Danilo. M. Teixeira , Rafael T. Toffoli

The planetary ephemeris is an essential tool for interplanetary spacecraft navigation, studies of solar system dynamics (including, for example, barycenter corrections for pulsar timing ephemeredes), the prediction of occultations, and…

Earth and Planetary Astrophysics · Physics 2015-05-20 D. L. Jones , E. Fomalont , V. Dhawan , J. Romney , W. M. Folkner , G. Lanyi , J. Border , R. Jacobson

The implementation of the simultaneous combination of several telescopes (from four to eight) available at Very Large Telescope Interferometer (VLTI) will allow the new generation interferometric instrumentation to achieve interferometric…

Astrophysics · Physics 2009-11-13 L. Corcione , D. Bonino , D. F. Busher , M. Gai , S. Ligori , D. Loreggia , G. Masssone , J. S. Young

Very long baseline interferometry (VLBI) provides the resolution needed to make precision measurements of a pulsar's parallax and proper motion. In making these measurements, the astronomer is faced with difficult calibration problems and a…

Astrophysics · Physics 2007-05-23 Walter Brisken

We analyse Very Long Baseline Interferometry (VLBI) observations of the blazar CGRaBS J0809+5341 using Bayesian inference methods. The observation was carried out at 5 GHz using 8 telescopes that form part of the European VLBI Network.…

Instrumentation and Methods for Astrophysics · Physics 2016-10-18 Iniyan Natarajan , Zsolt Paragi , Jonathan Zwart , Simon Perkins , Oleg Smirnov , Kurt van der Heyden

Astrometry at centimeter wavelengths using Very Long Baseline Interferometry is approaching accuracies of ~1 uas for the angle between a target and a calibrator source separated by <1 degree on the sky. The BeSSeL Survey and the Japanese…

Instrumentation and Methods for Astrophysics · Physics 2023-01-13 Mark J. Reid

A new list of physical characteristics of 3914 astrometric radio sources, including all 717 ICRF-Ext.2 sources, observed during IVS and NRAO VCS sessions have been compiled. The list includes source type, redshift and visual magnitude (if…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-06 Zinovy Malkin , Oleg Titov

Since its observation in 2019, the first image of a super-massive black hole using Very Long Baseline Interferometry (VLBI) with an Earth-scale baseline has generated much scientific and public interest, including the possible extension of…

Instrumentation and Methods for Astrophysics · Physics 2026-05-08 Eric Burt , Todd Ely , Geoff Bower , Joe Lazio , Marin Anderson , Sonia Hernandez

We present the description of the FAKERAT software developed for planning Very Long Baseline Interferometry observations from space (space-VLBI). The results of the planned observations using the FAKERAT package during the first two years…

Instrumentation and Methods for Astrophysics · Physics 2014-10-07 V. I. Zhuravlev

The VLTI Spectro Imager (VSI) was proposed as a second-generation instrument of the Very Large Telescope Interferometer providing the ESO community with spectrally-resolved, near-infrared images at angular resolutions down to 1.1…

Studying transient phenomena with the Very Long Baseline Interferometry (VLBI) technique faces severe difficulties because the turnaround time of the experiments from the observations to the scientific result is rather long. The e-VLBI…

Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To…

Instrumentation and Methods for Astrophysics · Physics 2011-06-02 Sheperd Doeleman , Tao Mai , Alan Rogers , John Hartnett , Michael Tobar , Nitin Nand

We made VLBI observations at 8.4 GHz between 1997 and 2005 to estimate the coordinates of the "core" component of the superluminal quasar, 3C 454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 N. Bartel , M. F. Bietenholz , D. E. Lebach , J. I. Lederman , L. Petrov , R. R. Ransom , M. I. Ratner , I. I. Shapiro

In this work, we report on activities focusing on improving the observation strategy of the Very Long Baseline Interferometry (VLBI) Global Observing System (VGOS). During six dedicated 24-hour Research and Development (R&D) sessions…

Instrumentation and Methods for Astrophysics · Physics 2023-12-01 Matthias Schartner , Bill Petrachenko , Mike Titus , Hana Krasna , John Barrett , Dan Hoak , Dhiman Mondal , Minghui Xu , Benedikt Soja

This paper presents the fifth part of the Very Long Baseline Array (VLBA) Calibrator Survey (VCS), containing 569 sources not observed previously with very long baseline interferometry in geodetic or absolute astrometry programs. This…

Astrophysics · Physics 2008-11-26 Y. Y. Kovalev , L. Petrov , E. B. Fomalont , D. Gordon

We propose a probabilistic framework for performing simultaneous estimation of source structure and fringe-fitting parameters in Very Long Baseline Interferometry (VLBI) observations. As a first step, we demonstrate this technique through…

Instrumentation and Methods for Astrophysics · Physics 2020-06-10 Iniyan Natarajan , Roger Deane , Ilse van Bemmel , Huib Jan van Langevelde , Des Small , Mark Kettenis , Zsolt Paragi , Oleg Smirnov , Arpad Szomoru

Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object…

Astrophysics of Galaxies · Physics 2015-06-12 Laurent Loinard