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A novel interferometric technique that uses the spectrum of the current fluctuations of a quadratic detector, a type of detector commonly used in Astronomy, has recently been introduced. It has major advantages with respect to classical…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 Ermanno F. Borra

We discuss the opacity in the core regions of active galactic nuclei observed with Very Long Baseline Interferometry (VLBI), and describe a new method for deriving the frequency-dependent shifts of the VLBI core from the frequency-dependent…

High Energy Astrophysical Phenomena · Physics 2015-05-28 N. A. Kudryavtseva , D. C. Gabuzda , M. F. Aller , H. D. Aller

Precision astrometry is an integral component of successful pulsar timing campaigns. Astrometric parameters are commonly derived by fitting them as parameters of a timing model to a series of pulse times of arrival (TOAs). TOAs measured to…

High Energy Astrophysical Phenomena · Physics 2013-12-12 D. R. Madison , S. Chatterjee , J. M. Cordes

Model misspecification is ubiquitous in data analysis because the data-generating process is often complex and mathematically intractable. Therefore, assessing estimation uncertainty and conducting statistical inference under a possibly…

Methodology · Statistics 2023-12-19 Rong Li , Yichen Qin , Yang Li

We revisit the "Cluster-Cluster" or multi-view Very-Long-Baseline-Interferometry (VLBI) technique from the perspective of its synergy with the multi-beam features inherent in the Australian Square Kilometer Array Pathfinder (ASKAP)and its…

Instrumentation and Methods for Astrophysics · Physics 2009-09-28 M. J. Rioja , R. Dodson , R. W. Porcas , D. Ferris , J. Reynolds , T. Sasao , R. T. Schilizzi

Stellar occultations currently provide the most accurate ground-based measurements of the positions of natural satellites (down to a few kilometres for the Galilean moons). However, when using these observations in the calculation of…

Earth and Planetary Astrophysics · Physics 2023-08-09 M. Fayolle , V. Lainey , D. Dirkx , L. I. Gurvits , G. Cimo , S. J. Bolton

While conventional imaging in VLBI provides information only about the relative position between different features of a given source, phase-referenced observations can provide precise positional information with respect to an external…

Astrophysics · Physics 2007-05-23 Eduardo Ros

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

Many important techniques for investigating the properties of extragalactic radio sources, such as spectral-index and rotation-measure mapping, involve the comparison of images at two or more frequencies. In the case of radio…

Astrophysics · Physics 2009-11-13 S. M. Croke , D. C. Gabuzda

A crucial part of a space mission for very-long baseline interferometery (VLBI), which is the technique capable of providing the highest resolution images in astronomy, is orbit determination of the mission's space radio telescope(s). In…

Very long baseline interferometry (VLBI) provides the highest-resolution images in astronomy. The sharpest resolution is nominally achieved at the highest frequencies, but as the observing frequency increases so too does the atmospheric…

Atmospheric propagation effects at millimeter wavelengths can significantly alter the phases of radio signals and reduce the coherence time, putting tight constraints on high frequency Very Long Baseline Interferometry (VLBI) observations.…

Long baseline radio interferometers can provide some interesting opportunities for future SETI searches. Known advantages (compared to single dishes or beam-formed arrays), include the large reduction in false-positives due to the…

Instrumentation and Methods for Astrophysics · Physics 2018-10-18 M. A. Garrett

We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The…

The technique of Very Long Baseline Interferometry (VLBI) can provide accurate localization and unique physical information about radio transients. However, it is still underutilized due to the inherent difficulties of VLBI data analysis…

Instrumentation and Methods for Astrophysics · Physics 2018-03-09 K. V. Sokolovsky , M. Giroletti , S. Corbel , G. E. Anderson , B. W. Stappers

Newly recognized effects of refractive scattering in the ionized interstellar medium have broad implications for very long baseline interferometry (VLBI) at extreme angular resolutions. Building upon work by Blandford & Narayan (1985), we…

Instrumentation and Methods for Astrophysics · Physics 2016-08-17 Michael D. Johnson , Ramesh Narayan

Results of a pilot project with the participation of the "Kvazar-KVO" radio interferometry array in observations carried out with the European VLBI Network are presented. The aim of the project was to conduct and analyze multi-frequency…

Astrophysics of Galaxies · Physics 2018-11-19 P. A. Voitsik , A. B. Pushkarev , Y. Y. Kovalev , A. V. Plavin , A. P. Lobanov , A. V. Ipatov

The Variable Bandpass Periodic Block Bootstrap(VBPBB) is an innovative method for time series with periodically correlated(PC) components. This method applies bandpass filters to extract specific PC components from datasets, effectively…

Methodology · Statistics 2025-09-25 Yanan Sun , Eric Rose , Kai Zhang , Edward Valachovic

An increasing number of blazars have been reported to show jet wobbling (i.e., non-regular rotations of the structural position angle of their innermost jets in the plane of the sky with amplitudes between 20 deg. and 50 deg., and time…

Astrophysics · Physics 2008-03-25 I. Agudo

Black hole imaging challenges the 3rd generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500 GHz band. The coherent integration time needed here is 450 s though the available space oscillators cannot offer more…

Instrumentation and Methods for Astrophysics · Physics 2021-09-20 V. Kudriashov , M. Martin-Neira , E. Lia , J. Michalski , P. Kant , D. Trofimowicz , M. Belloni , P. Jankovic , P. Waller , M. Brandt