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Soiling is the accumulation of dirt in solar panels which leads to a decreasing trend in solar energy yield and may be the cause of vast revenue losses. The effect of soiling can be reduced by washing the panels, which is, however, a…

Signal Processing · Electrical Eng. & Systems 2023-01-31 Alexandros Kalimeris , Ioannis Psarros , Giorgos Giannopoulos , Manolis Terrovitis , George Papastefanatos , Gregory Kotsis

The Subtractive Optimally Localized Averages (SOLA) method, developed and extensively used in helioseismology, is applied to artificial data to obtain measures of the sound speed inside a solar-type star. In contrast to inversion methods…

Astrophysics · Physics 2007-05-23 Sarbani Basu , J. Christensen-Dalsgaard , M. J. Thompson

The rotational Doppler effect, for which the frequency shift is proportional to the light's orbital angular momentum $\ell$ and the object's rotational speed ($\Delta f \propto\ell \Omega$), has proven to be a powerful tool for detecting…

Optics · Physics 2026-05-22 Juedong Yang , Yuan Li , Wuhong Zhang , Lixiang Chen

The topology and dynamics of the solar chromosphere are greatly affected by the presence of magnetic fields. The magnetic field can be inferred by analyzing polarimetric observations of spectral lines. Polarimetric signals induced by…

Solar and Stellar Astrophysics · Physics 2019-09-11 C. J. Díaz Baso , J. de la Cruz Rodríguez , S. Danilovic

We describe a method for removing ionospheric effects from single-frequency radio data a posteriori. This method is based on a theoretical climatological model developed by the USAF, which returns electron density as a function of position…

Astrophysics · Physics 2009-10-31 R. M. Campbell

During electro-optical testing of the camera for the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time, a unique low-signal pattern was found in differenced pairs of flat images used to create photon transfer curves, with…

Instrumentation and Methods for Astrophysics · Physics 2024-11-21 John Banovetz , Yousuke Utsumi , Joshua Meyers , Maya Beleznay , Andrew Rasmussen , Aaron Roodman

We present a technique for the accurate estimation of large-scale errors in an antenna surface using astronomical sources and detectors. The technique requires several out-of-focus images of a compact source and the signal-to-noise ratio…

Astrophysics · Physics 2009-11-11 B. Nikolic , R. E. Hills , J. S. Richer

Field observations form the basis of many scientific studies, especially in ecological and social sciences. Despite efforts to conduct such surveys in a standardized way, observations can be prone to systematic measurement errors. The…

Methodology · Statistics 2021-08-31 Shiv Shankar , Daniel Sheldon

Radio astronomical observations have very poor signal to noise ratios, unlike in other disciplines. On the other hand, it is possible to observe the object of interest for long time intervals as well as using a wider bandwidth.…

Astrophysics · Physics 2008-09-02 Sarod Yatawatta

We proposed an analytical model for the calculus of illumination time of the Earth for any time of year and any latitude, this model assumes the obliquity of the ecliptic as constant, the light beams as parallels, the Earth as spherical,…

Earth and Planetary Astrophysics · Physics 2012-10-15 Paco Talero , Fernanda Santana , César Mora

We present an adaptation of the rotation-corrected, m-averaged spectrum technique designed to observe low signal-to-noise-ratio, low-frequency solar p modes. The frequency shift of each of the 2l+1 m spectra of a given (n,l) multiplet is…

Solar and Stellar Astrophysics · Physics 2011-02-11 D. Salabert , J. Leibacher , T. Appourchaux , F. Hill

In this paper we present results from the NEFOCAST project, funded by the Tuscany Region, aiming at detecting and estimating rainfall fields from the opportunistic use of the rain-induced excess attenuation incurred in the downlink channel…

Signal Processing · Electrical Eng. & Systems 2019-07-25 Filippo Giannetti , Marco Moretti , Ruggero Reggiannini , Attilio Vaccaro

Imaging systems based on a narrow-band tunable filter are used to obtain Doppler velocity maps of solar features. These velocity maps are created by taking the difference between the blue- and red-wing intensity images of a chosen spectral…

Solar and Stellar Astrophysics · Physics 2010-09-16 Sreejith Padinhatteeri , R. Sridharan , K. Sankarasubramanian

We have developed a new method that uses wavelet analysis to remove interference fringe patterns from images. This method is particularly useful for flat fields in the common case where fringes vary between the calibration and object data.…

Astrophysics · Physics 2008-11-26 Patricio Rojo , Joseph Harrington

It is well known that the observed amplitude of solar oscillations is lower in sunspots than in quiet regions of the Sun. We show that this local reduction in oscillation amplitudes combined with the phase-speed filtering procedure in…

Astrophysics · Physics 2009-11-11 S. P. Rajaguru , A. C. Birch , T. L. Duvall , M. J. Thompson , J. Zhao

A long-standing issue in solar ground-based observations has been the contamination of data due to stray light, which is particularly relevant in inversions of spectropolarimetric data. We aim to build on a statistical method of correcting…

Solar and Stellar Astrophysics · Physics 2021-12-07 Sudharshan Saranathan , Michiel van Noort , Sami K. Solanki

In order to take full advantage of the long time series collected by the GONG and MDI helioseismic projects, we present here an adaptation of the rotation-corrected $m$-averaged spectrum technique in order to observe low radial-order solar…

Astrophysics · Physics 2009-06-23 David Salabert , John W. Leibacher , Thierry Appourchaux

Precise fiber positioning is crucial to a wide field, multi-fiber spectroscopic survey like LAMOST. Nowadays, most position error measurements are based on CCD photographic and imaging processing techniques. Those methods only work for…

Instrumentation and Methods for Astrophysics · Physics 2016-05-25 Jian-Jun Chen , Zhong-Rui Bai , A-Li Luo , Yong-Heng Zhao

Long-term observational data have information on the magnetic cycles of active stars and that of the Sun. The changes in the activity of our central star have basic effects on Earth, like variations in the global climate. Therefore…

Solar and Stellar Astrophysics · Physics 2015-05-13 Z. Kolláth , K. Oláh

Solar irradiance is fundamental data crucial for analyses related to weather and climate. High-precision estimation models are necessary to create areal data for solar irradiance. In this study, we developed a novel estimation model by…

Atmospheric and Oceanic Physics · Physics 2024-07-08 Jun Sasaki , Maki Okada , Kenji Utsunomiya , Koji Yamaguchi