English
Related papers

Related papers: Pixelization and Dynamic Range in Radio Interferom…

200 papers

Images taken by space telescopes typically have a superb spatial resolution, but a relatively poor sampling rate due to the finite CCD pixel size. Beyond the Nyquist limit, it becomes uncertain how much the pixelation effect may affect the…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-06 Zhi Shen , Jun Zhang , Hekun Li , Haoran Wang , Chengliang Wei , Guoliang Li , Xiaobo Li , Zhang Ban , Dan Yue

Bistatic radar measurements offer unique spatial diversity and enhanced target characterization capabilities, rendering them increasingly vital for contemporary sensing application research. The reliability of such measurements is…

We propose easy ways of correcting for the systematic errors caused by the photon noise and the pixelation effect in cosmic shear measurements. Our treatment of noise can reliably remove the noise contamination to the cosmic shear even when…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-16 Jun Zhang

Flying Triangulation sensors enable a free-hand and motion-robust 3D data acquisition of complex shaped objects. The measurement principle is based on a multi-line light-sectioning approach and uses sophisticated algorithms for real-time…

Computer Vision and Pattern Recognition · Computer Science 2013-05-20 Florian Willomitzer , Svenja Ettl , Christian Faber , Gerd Häusler

Synthesis imaging in radio astronomy is affected by instrumental and atmospheric effects which introduce direction-dependent (DD) gains.The antenna power pattern varies both as a function of time and frequency. The broad band time varying…

Instrumentation and Methods for Astrophysics · Physics 2014-11-18 Preshanth Jagannathan , Sanjay Bhatnagar , Urvashi Rau , Russ Taylor

Polarised radio synchrotron emission from interstellar, intracluster and intergalactic magnetic fields is affected by frequency-dependent Faraday depolarisation. The maximum polarised intensity depends on the physical properties of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Tigran G. Arshakian , Rainer Beck

We consider a troublesome form of non-isoplanatism in synthesis radio telescopes: non-coplanar baselines. We present a novel interpretation of the non-coplanar baselines effect as being due to differential Fresnel diffraction in the…

Astrophysics · Physics 2009-11-13 T. J. Cornwell , K. Golap , S. Bhatnagar

Approximate distance estimation can be used to determine fundamental landscape properties including complexity and openness. We show that variations in the skyline of landscape photos can be used to estimate distances to trees on the…

Computer Vision and Pattern Recognition · Computer Science 2022-01-24 Laura Martinez-Sanchez , Daniele Borio , Raphaël d'Andrimont , Marijn van der Velde

The Dragonfly Spectral Line Mapper is an innovative all-refracting telescope designed to carry out ultra-low surface brightness wide-field mapping of visible wavelength line emission. Equipped with ultranarrowband (0.8 nm bandwidth) filters…

We study the impact of the spread spectrum effect in radio interferometry on the quality of image reconstruction. This spread spectrum effect will be induced by the wide field-of-view of forthcoming radio interferometric telescopes. The…

Instrumentation and Methods for Astrophysics · Physics 2013-01-31 Laura Wolz , Filipe B. Abdalla , Rafael E. Carrillo , Yves Wiaux , Jason D. McEwen

Radio interferometric gain calibration can be biased by incomplete sky models and radio frequency interference, resulting in calibration artefacts that can restrict the dynamic range of the resulting images. It has been suggested that…

Instrumentation and Methods for Astrophysics · Physics 2019-10-21 Ulrich Armel Mbou Sob , Hertzog Landman Bester , Oleg Smirnov , Jonathan Kenyon , Trienko Grobler

The cosmological global (sky-averaged) 21-cm signal is a powerful tool to probe the evolution of the intergalactic medium (IGM) in high-redshift Universe ($z \leq 6$). One of the biggest observational challenges is to remove the foreground…

Instrumentation and Methods for Astrophysics · Physics 2018-11-14 Bang D. Nhan , Richard F. Bradley , Jack O. Burns

We report on a particular example of noise and data representation interacting to introduce systematic error. Many instruments collect integer digitized values and appy nonlinear coding, in particular square-root coding, to compress the…

Instrumentation and Methods for Astrophysics · Physics 2022-08-17 C. E. DeForest , C. Lowder , D. B. Seaton , M. J. West

Modern radio spectrometers make measurement of polarized intensity as a function of Faraday depth possible. I investigate the effect of depolarization along a model line of sight. I model sightlines with two components informed by…

Astrophysics of Galaxies · Physics 2018-12-04 A. S. Hill

This dissertation is concerned with understanding and analyzing some of the effects of diffraction in the near field. The contributions of homogeneous and of evanescent waves to two-dimensional near-field diffraction patterns of scalar…

Optics · Physics 2007-05-23 Marek W. Kowarz

Computer vision techniques enable automated detection of sky pixels in outdoor imagery. In urban climate, sky detection is an important first step in gathering information about urban morphology and sky view factors. However, obtaining…

Computer Vision and Pattern Recognition · Computer Science 2019-12-30 Kerry A. Nice , Jasper S. Wijnands , Ariane Middel , Jingcheng Wang , Yiming Qiu , Nan Zhao , Jason Thompson , Gideon D. P. A. Aschwanden , Haifeng Zhao , Mark Stevenson

Observations of the Sun from the Earth are always limited by the presence of the atmosphere, which strongly disturbs the images. A solution to this problem is to place the telescopes in space satellites, which produce observations without…

Solar and Stellar Astrophysics · Physics 2015-06-24 C. Quintero Noda , A. Asensio Ramos , D. Orozco Suárez , B. Ruiz Cobo

We study the impact of relativistic gravitational deflection of light on the accuracy of future Space Interferometry Mission (SIM). We estimate the deflection angles caused by the monopole, quadrupole and octupole components of…

General Relativity and Quantum Cosmology · Physics 2009-07-24 Slava G. Turyshev

Coherent interferometric scattering microscopy (iscat) enables nanoparticle tracking on microsecond timescales and with nanometer precision, and has become a key tool in structural and cellular biophysics. The achievable localization…

We study polarization effects in the nonlinear interference of photons generated via frequency non-degenerate spontaneous parametric down conversion. Signal and idler photons generated in the visible and infrared (IR) range, are split in…

Quantum Physics · Physics 2020-12-03 Anna Paterova , Hongzhi Yang , Chengwu An , Dmitry Kalashnikov , Leonid Krivitsky