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signal direction-of-arrival estimation using an array of sensors has been the subject of intensive research and development during the last two decades. Efforts have been directed to both, better solutions for the general data model and to…

Information Theory · Computer Science 2009-11-13 Farzan Haddadi , Mohammad Mahdi Nayebi , Mohammad Reza Aref

Gamma ray burst sources are isotropically distributed. They could be located at distances $\sim 1000$ AU. (Katz \cite{JK92}) GRB signals have many narrow peaks that are unresolved at the millisecond time resolution of existing observations.…

Astrophysics · Physics 2007-05-23 Frank D. Smith

We have cross matched the Gaia Data Release 1 secondary dataset that contains positions of 1.14 billion objects against the most complete to date catalogue of VLBI positions of 11.4 thousand sources, almost exclusively active galactic…

Astrophysics of Galaxies · Physics 2017-02-08 L. Petrov , Y. Y. Kovalev

Context: Phase referencing is a standard calibration technique in radio interferometry, particularly suited for the detection of weak sources close to the sensitivity limits of the interferometers. However, effects from a changing…

Instrumentation and Methods for Astrophysics · Physics 2015-05-18 I. Marti-Vidal , E. Ros , M. A. Perez Torres , J. C. Guirado , S. Jimenez-Monferrer , J. M. Marcaide

An interstellar communication network benefits from relay nodes placed in the gravitational lenses of stars. The signal gains are of order $10^{9}$ with optimal alignment, allowing for GBits connections at kW power levels with meter-sized…

Instrumentation and Methods for Astrophysics · Physics 2021-04-21 Michael Hippke

When VLBI observations are used to determine the position or motion of a radio source relative to reference sources nearby on the sky, the astrometric information is usually obtained via: (i) phase-referenced maps; or (ii) parametric model…

Instrumentation and Methods for Astrophysics · Physics 2019-08-13 D. E. Lebach , N. Bartel , M. F. Bietenholz , R. M. Campbell , D. Gordon , J. I. Lederman , J. -F. Lestrade , R. R. Ransom , M. I. Ratner , I. I. Shapiro

Unveiling the intergalactic magnetic field (IGMF) in filaments of galaxies is a very important and challenging subject in modern astronomy. In order to probe the IGMF from rotation measures (RMs) of extragalactic radio sources, we need to…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Takuya Akahori , Kohei Kumazaki , Keitaro Takahashi , Dongsu Ryu

Radio continuum emission has the potential to be an extinction-free tracer of star formation. However, the relation between radio continuum luminosity and star formation rate, the radio-SFR relation, is affected by various effects such as…

In this paper, I will take a synoptic approach to determining the intergalactic infrared radiation field (IIRF). This approach draws on both the multi-TeV gamma-ray observations and the infrared background observations and relates them via…

Astrophysics · Physics 2007-05-23 F. W. Stecker

We observed M51 at three frequencies, 1.4GHz (20cm), 4.9GHz (6cm) and 8.4GHz (3.6cm), with the VLA and the Effelsberg 100m telescope to obtain the highest quality radio continuum images of a nearby spiral galaxy. These radio data were…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 G. Dumas , E. Schinnerer , F. S. Tabatabaei , R. Beck , T. Velusamy , E. Murphy

The International Gamma-ray Astrophysics Laboratory (INTEGRAL) has been surveying the sky above 20 keV since its launch in 2002 providing new insights into the nature of the sources that populate our Universe at soft gamma-ray energies. The…

An important topic of interest in imaging is the construction of protocols that are not diffraction limited. This can be achieved in a variety of ways, including classical superresolution techniques or quantum entanglement-based protocols.…

Quantum Physics · Physics 2015-10-28 Mark E. Pearce , Thomas Mehringer , J. von Zanthier , Pieter Kok

Rotation measure (RM) grids of extragalactic radio sources have been widely used for studying cosmic magnetism. But their potential for exploring the intergalactic magnetic field (IGMF) in filaments of galaxies is unclear, since other…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Takuya Akahori , B. M. Gaensler , Dongsu Ryu

Wide-field images made by radio interferometers are invariably affected by direction-dependent systematic effects such as the ionosphere or the beam pattern. Calibration along a set of discrete directions in the sky is the default technique…

Instrumentation and Methods for Astrophysics · Physics 2026-02-06 Sebastiaan van der Tol , Sarod Yatawatta , Bram Veenboer , David Rafferty

Calibration is a key step in the signal processing pipeline of any radio astronomical instrument. The required sky, ionospheric and instrumental models for this step can suffer from various kinds of incompleteness. In this paper we analyze…

Instrumentation and Methods for Astrophysics · Physics 2019-02-08 A. Mouri Sardarabadi , L. V. E. Koopmans

The definition and optimisation studies for the Gaia satellite spectrograph, the Radial Velocity Spectrometer (RVS), converged in late 2002 with the adoption of the instrument baseline. This paper reviews the characteristics of the selected…

We consider a possibility of detecting the jitter effect of apparent celestial positions of distant sources due to local fluctuations of the Galaxy gravitational field. It is proposed to observe two samples of extragalactic sources (target…

Astrophysics of Galaxies · Physics 2020-07-29 Tatiana I. Larchenkova , Natalia Lyskova , Leonid Petrov , Alexander A. Lutovinov

The Square Kilometer Array (SKA) is expected to detect high-redshift galaxies with star formation rates (SFRs) up to two orders of magnitude lower than Herschel surveys and will thus boost the ability of radio astronomy to study…

Astrophysics of Galaxies · Physics 2022-01-26 K. Tisanić , G. De Zotti , A. Amiri , A. Khoram , S. Tavasoli , Z. Vidović-Tisanić

Context. High accuracy astrometric instruments like Gaia aiming at an accuracy of 1 microarcsecond cannot be considered as point-like observers in the framework of relativistic modelling of observable quantities. Aims. Special-relativistic…

Astrophysics · Physics 2007-05-23 G. Anglada-Escude , S. Klioner , M. Soffel , J. Torra

To effectively retrieve objects from large corpus with high accuracy is a challenge task. In this paper, we propose a method that propagates visual feature level similarities on a Markov random field (MRF) to obtain a high level…

Computer Vision and Pattern Recognition · Computer Science 2013-12-30 Peng Lu , Xujun Peng , Xinshan Zhu , Xiaojie Wang