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Context. Very Long Baseline Interferometry (VLBI) data are extremely sensitive to the phase stability of the VLBI array. This is especially important when we reach {\mu}Jy r.m.s. sensitivities. Calibration using standard phase referencing…

Instrumentation and Methods for Astrophysics · Physics 2016-02-24 Jack F. Radcliffe , Michael A. Garrett , Rob J. Beswick , Tom W. B. Muxlow , Peter Barthel , Adam T. Deller , Enno Middelberg

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

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

The past decade has seen significant advances in wide-field cm-wave very long baseline interferometry (VLBI), which is timely given the wide-area, synoptic survey-driven strategy of major facilities across the electromagnetic spectrum.…

We present GASV, a novel Python-based software package specifically designed for the analysis of Very Long Baseline Interferometry (VLBI) data. Developed with ease of installation and user friendliness in mind, GASV supports both pipeline…

Instrumentation and Methods for Astrophysics · Physics 2026-02-05 Dang Yao , Yuan-wei Wu , Xu-hai Yang

We present our implementation of an automated VLBI data reduction pipeline dedicated to interferometric data imaging and analysis. The pipeline can handle massive VLBI data efficiently which makes it an appropriate tool to investigate…

Instrumentation and Methods for Astrophysics · Physics 2017-12-07 M. Zhang , A. Collioud , P. Charlot

In long baseline interferometry, the raw fringe contrast must be calibrated to obtain the true visibility and then those observables that can be interpreted in terms of astrophysical parameters. The selection of suitable calibration stars…

High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 R. Dodson , M. Rioja , Y. Asaki , H. Imai , X. -Y. Hong , Z. Shen

Image reconstruction in very-long baseline interferometry operates under severely sparse aperture coverage with calibration challenges from both the participating instruments and propagation medium, which introduce the risk of biases and…

Instrumentation and Methods for Astrophysics · Physics 2026-01-14 Samuel Lai , Nithyanandan Thyagarajan , O. Ivy Wong , Foivos Diakogiannis

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

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…

Very Long Baseline Interferometry (VLBI) astrometry is a well established technique for achieving $\pm10~\mu$as parallax accuracies at frequencies well above 10~GHz. At lower frequencies, uncompensated interferometer delays associated with…

Instrumentation and Methods for Astrophysics · Physics 2023-02-15 Lucas J. Hyland , Mark J. Reid , Simon P. Ellingsen , Maria J. Rioja , Richard Dodson , Gabor Orosz , Colin R. Masson , Jamie M. McCallum

Optical Very Long Baseline Interferometry (VLBI) offers the potential for unprecedented angular resolution in both astronomical imaging and precision measurements. Classical approaches, however, face significant limitations due to photon…

Quantum Physics · Physics 2025-12-24 Zixin Huang , Oleg Titov , Mikolaj K. Schmidt , Benjamin Pope , Gavin K. Brennen , Daniel Oi , Pieter Kok

For short-wavelength VLBI observations, it is difficult to measure the phase of the visibility function accurately. The closure phases are reliable measurements under this situation, though it is not sufficient to retrieve all of the phase…

Instrumentation and Methods for Astrophysics · Physics 2018-07-20 Shiro Ikeda , Fumie Tazaki , Kazunori Akiyama , Kazuhiro Hada , Mareki Honma

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

The observation and imaging of hundreds or thousands of radio sources with the technique of very long baseline interferometry (VLBI) is a computationally intensive task. However, these surveys allow us to conduct statistical investigations…

Astrophysics of Galaxies · Physics 2017-06-28 Kristóf Rozgonyi , Sándor Frey

We report the development of a semi-automatic pipeline for the calibration of 86 GHz full-polarization observations performed with the Global Millimeter-VLBI array (GMVA) and describe the calibration strategy followed in the data reduction.…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 I. Marti-Vidal , T. P. Krichbaum , A. Marscher , W. Alef , A. Bertarini , U. Bach , F. K. Schinzel , H. Rottmann , J. M. Anderson , J. A. Zensus , M. Bremer , S. Sanchez , M. Lindqvist , A. Mujunen

This paper presents the sixth part to the Very Long Baseline Array (VLBA) Calibrator Survey. It contains the positions and maps of 264 sources of which 169 were not previously observed with very long baseline interferometry (VLBI). This…

Astrophysics · Physics 2008-07-21 L. Petrov , Y. Y. Kovalev , E. B. Fomalont , D. Gordon

Very long baseline interferometry (VLBI) achieves the highest angular resolution in astronomy. VLBI measures corrupted Fourier components, known as visibilities. Reconstructing on-sky images from these visibilities is a challenging inverse…

Instrumentation and Methods for Astrophysics · Physics 2025-11-25 Paul Tiede , William Moses , Valentin Churavy , Michael D. Johnson , Dominic Pesce , Lindy Blackburn , Peter Galison

This paper presents the fourth extension to the Very Long Baseline Array (VLBA) Calibrator Survey, containing 258 new sources not previously observed with very long baseline interferometry (VLBI). This survey, based on three 24 hour VLBA…

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