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We calculate global (unified) wind models of main-sequence, giant, and supergiant O stars from our Galaxy. The models are calculated by solving hydrodynamic, kinetic equilibrium (also known as NLTE) and comoving-frame (CMF) radiative…

Solar and Stellar Astrophysics · Physics 2017-10-04 Jiri Krticka , Jiri Kubat

Differential atmospheric dispersion is a wavelength-dependent effect introduced by Earth's atmosphere that affects astronomical observations performed using ground-based telescopes. It is important, when observing at a zenithal angle…

Instrumentation and Methods for Astrophysics · Physics 2021-03-17 B. Wehbe. , A. Cabral , L. Sbordone , G. Avila

Data set generated from the scintillation detector is used to build a mathematical model based on three different algorithms: (a) Multiple Polynomial Regression (b) Support Vector Regression (c) Neural Network algorithm. Using…

Instrumentation and Detectors · Physics 2021-12-21 Navaneeth P. R. , Kajal Kumari , Mayank Goswami

This paper introduces the concept of adaptive temporal compressive sensing (CS) for video. We propose a CS algorithm to adapt the compression ratio based on the scene's temporal complexity, computed from the compressed data, without…

Applications · Statistics 2016-11-17 Xin Yuan , Jianbo Yang , Patrick Llull , Xuejun Liao , Guillermo Sapiro , David J. Brady , Lawrence Carin

In-camera light scattering is a typical form of non-systematic interference in indirect Time-of-Flight (iToF) cameras, primarily caused by multiple reflections and optical path variations within the camera body. This effect can…

Optics · Physics 2025-11-05 Yansong Du , Jingtong Yao , Yuting Zhou , Feiyu Jiao , Zhaoxiang Jiang , Xun Guan

This paper proposes an adaptive time-stepping mothods for stochastic diffusion systems whose drift and diffusion coefficients are locally Lipschitz continuous and may exhibit polynomial growth. By controlling the growth of both the drift…

Numerical Analysis · Mathematics 2026-02-09 Xueqi Wen , Guozhen Li , Yuanping Cui , Xiaoyue Li

The SINFONI instrument for ESO's VLT combines integral field spectroscopy and adaptive optics (AO). We discuss detailed simulations of the adaptive optics module. These simulations are aimed at assessing the AO module performance,…

Astrophysics · Physics 2009-11-10 Anthony G A Brown , Enrico Fedrigo , Paul van der Werf

The implementation of efficient free-space channels is fundamental for both classical and quantum Free-Space Optical (FSO) communication. This can be challenging for fibre-coupled receivers, due to the time variant inhomogeneity of the…

The ability to simulate atmospheric turbulence in the lab is a crucial part of testing and developing astronomical adaptive optics technology. We report on the development of a technique for creating phase plates, which involves the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Rachel Rampy , Don Gavel , Daren Dillon , Sandrine Thomas

Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using…

Instrumentation and Methods for Astrophysics · Physics 2016-03-04 Peng Kian Tan , Aik Hui Chan , Christian Kurtsiefer

Meteorological data have been used to calculate refractive index fluctuations - the indicator of optical instability of the Earth's atmosphere. The calculations were made for standard pressure levels of the atmosphere in winter and summer.…

Instrumentation and Methods for Astrophysics · Physics 2011-01-21 Pavel G. Kovadlo , Olga S. Kochetkova

In this letter we describe a new method to use Baryon Acoustic Oscillations (BAO) to derive a constraint on the possible variation of the speed of light. The method relies on the fact that there is a simple relation between the angular…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-18 Vincenzo Salzano , Mariusz P. Dabrowski , Ruth Lazkoz

Calculations of atmospheric refraction are generally based on a simplified model of atmospheric density in the troposphere which assumes that the temperature decreases at a constant lapse rate from sea level up to a height equal to eleven…

Atmospheric and Oceanic Physics · Physics 2016-09-29 Michael Nauenberg

In adaptive optics, the measurement of spatial coherence length helps in deciding the optimum design parameters of a Shack Hartmann Sensor (SHS). Two methods of estimating the spatial coherence length of optical wavefronts are presented.…

Instrumentation and Methods for Astrophysics · Physics 2009-11-08 Akondi Vyas , M. B. Roopashree , B. Raghavendra Prasad

The effects of anisoplanatism on the adaptive optics point spread function are investigated. A model is derived that combines observations of the guide star with an analytic formulation of anisoplanatism to generate predictions for the…

Astrophysics · Physics 2009-11-11 Matthew Britton

We present the photometric calibration of the HST Advanced Camera for Surveys (ACS). We give here an overview of the performance and calibration of the 2 CCD cameras, the Wide Field Channel (WFC) and the High Resolution Channel (HRC), and a…

The orbital angular momentum (OAM) of photons is a promising degree of freedom for high-dimensional quantum key distribution (QKD). However, effectively mitigating the adverse effects of atmospheric turbulence is a persistent challenge in…

Signal Processing · Electrical Eng. & Systems 2020-06-24 Jiapeng Zhao , Yiyu Zhou , Boris Braverman , Cong Liu , Kai Pang , Nicholas K. Steinhoff , Glenn A. Tyler , Alan E. Willner , Robert W. Boyd

Images obtained with single-conjugate adaptive optics (AO) show spatial variation of the point spread function (PSF) due to both atmospheric anisoplanatism and instrumental aberrations. The poor knowledge of the PSF across the field of view…

This study introduces a novel frequency-based data-driven controller for adaptive optics, using power spectral density for optimization while ensuring stability criteria. It addresses disturbance rejection, command amplitude constraints and…

The free-space optical channel has the potential to facilitate inexpensive, wireless communication with fiber-like bandwidth under short deployment timelines. However, atmospheric effects can significantly degrade the reliability of a…

Information Theory · Computer Science 2008-04-02 Nick Letzepis , Albert Guillen i Fabregas