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200 papers

To increase the number of sources with Very Long Baseline Interferometry (VLBI) astrometry available for comparison with the Gaia results, we have observed 31 young stars with recently reported radio emission. These stars are all in the…

Solar and Stellar Astrophysics · Physics 2024-06-12 Sergio A. Dzib , Laurent Loinard , Ralf Launhardt , Jazmín Ordóñez-Toro

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

Fast Radio Bursts (FRBs) are short, intense radio signals from distant astrophysical sources, and their accurate localisation is crucial for probing their origins and utilising them as cosmological tools. This study focuses on improving the…

Instrumentation and Methods for Astrophysics · Physics 2025-06-18 Akhil Jaini , Adam T. Deller , Yuanming Wang , Emil Lenc , Marcin Glowacki

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

The calibration and analysis of polarization observations in Very Long Baseline Interferometry (VLBI) requires the use of specific algorithms that suffer from several limitations, closely related to assumptions in the data properties that…

Instrumentation and Methods for Astrophysics · Physics 2021-02-10 Ivan Marti-Vidal , Alejandro Mus , Michael Janssen , Pablo de Vicente , Javier Gonzalez

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

GHz-peaked spectrum (GPS) radio sources are thought to be young objects which later evolve into FR-I and FR-II radio galaxies. We have used the Australia Telescope 20GHz (AT20G) survey catalogue to select a uniform sample of GPS sources…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Paul J. Hancock , Steven J. Tingay , Elaine M. Sadler , Chris Phillips , Adam T. Deller

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

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

In this white paper, we propose an upgrade to the Very Large Telescope Interferometer (VLTI) consisting of the addition of a new 8m Unit Telescope (UT5). The primary goal of this upgrade is to optimise the VLTI for exoplanet detection by…

Instrumentation and Methods for Astrophysics · Physics 2025-12-22 Óscar Carrión-González , Sylvestre Lacour , Mathias Nowak

The accuracy of orbit determination has a strong impact on the scientific output of the Space VLBI mission RadioAstron. The aim of this work is to improve the RadioAstron orbit reconstruction by means of sophisticated dynamical modelling of…

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

VLBI plays a unique and fundamental role in the maintenance of global reference frames which are required for precise positioning in many research areas related e.g to the understanding and monitoring of global changes, to geodesy, to space…

Astrophysics · Physics 2007-05-23 W. Schluter , N. Vandenberg

By linking widely separated radio dishes, the technique of very long baseline interferometry (VLBI) can greatly enhance angular resolution in radio astronomy. However, at any given moment, a VLBI array only sparsely samples the information…

Systematic surveys of astronomical objects often lead to discoveries, but always provide invaluable information for statistical studies of well-defined samples. They also promote follow-up investigations of individual objects or classes.…

Astrophysics · Physics 2008-11-26 S. Frey

Global Positioning System (GPS) satellites broadcast at frequencies of 1,575.42 MHz (L1) and of 1,227.60 MHz (L2). The dispersive property of the ionosphere can be used to combine independent measurements at the two frequencies to estimate…

Astrophysics · Physics 2007-05-23 E. Ros , J. M. Marcaide , J. C. Guirado , E. Sardon , I. I. Shapiro

We demonstrate the blind interferometric detection and localization of two fast radio bursts (FRBs) with 2- and 25-arcsecond precision on the 400-m baseline between the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and the CHIME…

The VDFS comprises the system to pipeline process and archive the data from infrared observations taken by both the WFCAM instrument on UKIRT and the forthcoming VISTA telescope. These include the largest near-IR surveys to date, such as…

Astrophysics · Physics 2007-11-02 Nicholas Cross , Nigel Hambly , Ross Collins , Mike Read , Eckhard Sutorius

Joint observations of gravitational waves and electromagnetic counterparts will answer questions about cosmology, gamma-ray bursts, and the behaviour of matter at supranuclear densities. The addition of a Southern-Hemisphere…

General Relativity and Quantum Cosmology · Physics 2024-01-12 James W. Gardner , Ling Sun , Ssohrab Borhanian , Paul D. Lasky , Eric Thrane , David E. McClelland , Bram J. J. Slagmolen

The upgrade of the VLTI infrastructure for the 2nd generation instruments is now complete with the transformation of the laboratory, and installation of star separators on both the 1.8-m Auxiliary Telescopes (ATs) and the 8-m Unit…