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This chapter aims to provide a review of the basics of 21 cm interferometric observations and its methodologies. A summary of the main concepts of radio interferometry and their connection with the 21 cm observables - power spectra and…

Instrumentation and Methods for Astrophysics · Physics 2019-09-27 G. Bernardi

We propose a new method for solving an important problem of astronomy that arises in observations with ultrahigh-angular-resolution interferometers. This method is based on the application of the theory of artificial neural networks. We…

Instrumentation and Methods for Astrophysics · Physics 2019-06-26 Alexander Shatskiy , Ivan Evgeniev

We review the systematic uncertainties that have plagued attempts to obtain high precision and high accuracy from ground-based photometric measurements using CCDs. We identify two main challenges in breaking through the 1% precision…

Astrophysics · Physics 2008-11-26 Christopher W. Stubbs , John L. Tonry

Astronomical imaging can be broadly classified into two types. The first type is amplitude interferometry, which includes conventional optical telescopes and Very Large Baseline Interferometry (VLBI). The second type is intensity…

Instrumentation and Methods for Astrophysics · Physics 2022-05-04 Manuel Bojer , Zixin Huang , Sebastian Karl , Stefan Richter , Pieter Kok , J. von Zanthier

The detection reliability of weak signals is a critical issue in many astronomical contexts and may have severe consequences for determining number counts and luminosity functions, but also for optimising the use of telescope time in…

Instrumentation and Methods for Astrophysics · Physics 2016-04-06 Roberto Vio , Paola Andreani

Straightforward methods for adapting the familiar chi^2 statistic to histograms of discrete events and other Poisson distributed data generally yield biased estimates of the parameters of a model. The bias can be important even when the…

Data Analysis, Statistics and Probability · Physics 2014-03-12 Joseph W. Fowler

In this paper, we describe the principle of a multi-aperture interferometer that uses a phase-shifting technique and is suitable for quick, snapshot imaging of astrophysical objects at extreme angular resolution through Fourier inversion. A…

Optics · Physics 2015-05-28 Francois Henault

The next generation Very Large Array project (ngVLA) would represent a major step forward in sensitivity and resolution for radio astronomy, with ability to achieve 2 milli-arcsec resolution at 100 GHz (assuming a maximum baseline of 300…

Instrumentation and Methods for Astrophysics · Physics 2017-06-12 David T. Frayer

Modern radio telescopes strongly rely on accurate computational electromagnetic tools for "beam" models. Especially for densely-packed aperture array radio telescopes, the only feasible way to produce accurate models of the individual…

Instrumentation and Methods for Astrophysics · Physics 2023-06-13 Pietro Bolli , David Davidson , Maria Grazia Labate , Stefan J. Wijnholds

Redundant calibration is a technique in radio astronomy that allows calibration of radio arrays whose antennas lie on a lattice by exploiting the fact that redundant baselines should see the same sky signal. Because the number of measured…

Instrumentation and Methods for Astrophysics · Physics 2022-08-17 Prakruth Adari , Anže Slosar

The problem of astrometry is revisited from the perspective of analyzing the attainability of well-known performance limits (the Cramer-Rao bound) for the estimation of the relative position of light-emitting (usually point-like) sources on…

Instrumentation and Methods for Astrophysics · Physics 2018-09-05 Sebastian Espinosa , Jorge F. Silva , Rene A. Mendez , Rodrigo Lobos , Marcos Orchard

Stellar intensity interferometers correlate photons within their coherence time and could overcome the baseline limitations of existing amplitude interferometers. Intensity interferometers do not rely on phase coherence of the optical…

Instrumentation and Methods for Astrophysics · Physics 2022-02-24 Sebastian Karl , Andreas Zmija , Stefan Richter , Naomi Vogel , Dmitry Malyshev , Adrian Zink , Thilo Michel , Gisela Anton , Joachim von Zanthier , Stefan Funk

In real telescopes, the optical parameters evolve with time, and the degradation is often not uniform. This introduces variations in the image profile and therefore photo-centre displacements which, unless corrected, may result in…

Astrophysics · Physics 2009-11-13 M. Gai , R. Cancelliere

We propose a method to build an astronomical interferometer using continuous variable quantum teleportation to overcome the transmission loss between distant telescopes. The scheme relies on two-mode squeezed states shared by distant…

Quantum Physics · Physics 2025-09-03 Yunkai Wang , Yujie Zhang , Virginia O. Lorenz

Baseline calibration of a stellar interferometer is a prerequisite to data reduction of astrometric operations. This technique of astrometry is triangulation of star positions. Since angles are deduced from the baseline and delay side of…

Instrumentation and Methods for Astrophysics · Physics 2009-06-16 Richard J. Mathar

Radio interferometry most commonly involves antennas or antenna arrays of identical design. The identical antenna assumption leads to a convenient and useful mathematical simplification resulting in a scalar problem. An interesting variant…

Instrumentation and Methods for Astrophysics · Physics 2017-10-11 Adrian T. Sutinjo , Daniel Ung , Tim M. Colegate , Randall B. Wayth , Peter J. Hall , Eloy de Lera Acedo

Aims: Optical interferometry from space for the purpose of detecting and characterising exoplanets is seeing a revival, specifically from missions such as the proposed Large Interferometer For Exoplanets (LIFE). A default assumption since…

Instrumentation and Methods for Astrophysics · Physics 2022-08-10 Jonah T. Hansen , Michael J. Ireland , the LIFE Collaboration

The paper reviews progress in imaging in radio interferometry for the period 1993-1996. Unlike an optical telescope, the basic measurements of a radio interferometer (correlations between antennas) are indirectly related to a sky brightness…

Astrophysics · Physics 2007-05-23 R. J. Sault , T. A. Oosterloo

Atmospheric propagation errors are a main constraint on the accuracy of Very Long Baseline Interferometry (VLBI) astrometry. For relative astrometry, differential techniques can mitigate these errors, but their effectiveness diminishes with…

Instrumentation and Methods for Astrophysics · Physics 2025-05-26 Jingdong Zhang , Bo Zhang , Shuangjing Xu , Maria J. Rioja , Richard Dodson , Xiaofeng Mai , Oleg Titov

The discovery and subsequent study of optical counterparts to transient sources is crucial for their complete astrophysical understanding. Various gamma ray burst (GRB) detectors, and more notably the ground--based gravitational wave…

Instrumentation and Methods for Astrophysics · Physics 2022-09-29 Javed Rana , Akshat Singhal , Bhooshan Gadre , Varun Bhalerao , Sukanta Bose
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