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The extraction of the sky-averaged 21 cm signal from Cosmic Dawn and the Epoch of Reionization faces significant challenges. The bright and anisotropic Galactic foreground, which is 4 - 5 orders of magnitude brighter than the 21 cm signal,…

Instrumentation and Methods for Astrophysics · Physics 2025-12-10 Haoran Li , Furen Deng , Meng Zhou , Yidong Xu , Xuelei Chen

We use dynamical mean field theory to find an exact solution for inelastic light scattering in strongly correlated materials such as those near a quantum-critical metal-insulator transition. We evaluate the results for $\textbf{q}=0$…

Strongly Correlated Electrons · Physics 2009-11-10 A. M. Shvaika , O. Vorobyov , J. K. Freericks , T. P. Devereaux

Deconvolution is essential for radio interferometric imaging to produce scientific quality data because of finite sampling in the Fourier plane. Most deconvolution algorithms are based on CLEAN which uses a grid of image pixels, or clean…

Instrumentation and Methods for Astrophysics · Physics 2016-11-18 Sarod Yatawatta

Radio astronomy plays a crucial role in understanding the universe, particularly within the realm of non-thermal astrophysics. Images of celestial objects are derived from the signals (called visibility) measured by radio telescopes. Such…

Computer Vision and Pattern Recognition · Computer Science 2026-04-21 Kai Cheng , Ruoqi Wang , Qiong Luo

Infrared space interferometers can surpass the spatial resolution limitations of single-dish space telescopes. However, stellar interferometers from space have not been realized because of technical difficulties. Two beams coming from…

Instrumentation and Methods for Astrophysics · Physics 2022-01-20 Taro Matsuo , Satoshi Ikari , Hirotaka Kondo , Sho Ishiwata , Shinichi Nakasuka , Tomoyasu Yamamuro

This paper presents a case study from a single, six-hour observing period to illustrate the application of techniques developed for interferometric radio telescopes to the spectral analysis of observations of ionospheric fluctuations with…

Space Physics · Physics 2014-02-05 Joseph Helmboldt , Huib Intema

In long-baseline interferometry, bandwidth smearing of an extended source occurs at finite bandwidth when its different components produce interference packets that only partially overlap. In this case, traditional model fitting or image…

Instrumentation and Methods for Astrophysics · Physics 2013-08-07 Régis Lachaume , Jean-Philippe Berger

We proposed a novel approach to coherent imaging of dynamic samples. The inter-frame similarity of the sample's local structures is found to be a powerful constraint in phasing a sequence of diffraction patterns. We devised a new image…

Optics · Physics 2024-07-11 Pengju Sheng , Fucai Zhang

Aerial object detection is a challenging task, in which one major obstacle lies in the limitations of large-scale data collection and the long-tail distribution of certain classes. Synthetic data offers a promising solution, especially with…

Computer Vision and Pattern Recognition · Computer Science 2023-11-22 Yanan Jian , Fuxun Yu , Simranjit Singh , Dimitrios Stamoulis

Images from adaptive optics systems are generally affected by significant distortions of the point spread function (PSF) across the field of view, depending on the position of natural and artificial guide stars. Image reduction techniques…

Instrumentation and Methods for Astrophysics · Physics 2015-06-24 Andrea La Camera , Laura Schreiber , Emiliano Diolaiti , Patrizia Boccacci , Mario Bertero , Michele Bellazzini , Paolo Ciliegi

The sky-averaged (global) highly redshifted 21-cm spectrum from neutral hydrogen is expected to appear in the VHF range of $\sim20-200$ MHz and its spectral shape and strength are determined by the heating properties of the first stars and…

Instrumentation and Methods for Astrophysics · Physics 2018-10-24 Keith Tauscher , David Rapetti , Jack O. Burns , Eric R. Switzer

Planetary-mass objects and brown dwarfs at the transition ($\rm{T}_{eff}\sim1300$\,K) from relatively red L dwarfs to bluer mid-T dwarfs show enhanced spectrophotometric variability. Multi-epoch observations support atmospheric…

Earth and Planetary Astrophysics · Physics 2024-05-21 Michael K. Plummer , Ji Wang , Étienne Artigau , René Doyon , Genaro Suárez

We describe a technique for deriving effective temperatures, surface gravities, rotation velocities, and radial velocities from high resolution near-IR spectra. The technique matches the observed near-IR spectra to spectra synthesized from…

Astrophysics · Physics 2009-11-10 G. W. Doppmann , D. T. Jaffe

The Australia Telescope Compact Array and the Very Large Array are currently being upgraded to operate with wide bandwidths; interferometers dedicated to the measurement of cosmic microwave background anisotropies are being designed with…

Astrophysics · Physics 2009-11-10 Ravi Subrahmanyan

The spatial-frequency coverage of a radio interferometer is increased by combining samples acquired at different times and observing frequencies. However, astrophysical sources often contain complicated spatial structure that varies within…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 U. Rau

Solar activity, such as flares, produce bursts of high-energy radiation that temporarily enhance the D-region of the ionosphere and attenuate low-frequency radio waves. To track these Sudden Ionospheric Disturbances (SIDs), which disrupt…

Solar and Stellar Astrophysics · Physics 2018-09-11 Sahil Hegde , Monica G. Bobra , Philip H. Scherrer

The fields of view of Extremely Large Telescopes will contain vast numbers of spatial sampling elements (spaxels) as their Adaptive Optics systems approach the diffraction limit over wide fields. Since this will exceed the detection…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 G. J. Murray , J. R. Allington-Smith

The integral-field unit (IFU) spectrometers on board the James Webb Space Telescope (JWST) undersample the nearly diffraction-limited point spread function provided by the telescope optics. This undersampling produces large oscillating…

Instrumentation and Methods for Astrophysics · Physics 2026-03-31 David R. Law , Melanie Clarke

Contamination due to foregrounds (Galactic and Extra-galactic), calibration errors and ionospheric effects pose major challenges in detection of the cosmic 21 cm signal in various Epoch of Reionization (EoR) experiments. We present the…

Instrumentation and Methods for Astrophysics · Physics 2018-05-15 B. K. Gehlot , L. V. E. Koopmans , A. G. de Bruyn , S. Zaroubi , M. A. Brentjens , K. M. B. Asad , M. Hatef , V. Jelic , M. Mevius , A. R. Offringa , V. N. Pandey , S. Yatawatta

Modern cameras with large apertures often suffer from a shallow depth of field, resulting in blurry images of objects outside the focal plane. This limitation is particularly problematic for fixed-focus cameras, such as those used in smart…

Computer Vision and Pattern Recognition · Computer Science 2025-10-28 Xinge Yang , Chuong Nguyen , Wenbin Wang , Kaizhang Kang , Wolfgang Heidrich , Xiaoxing Li
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