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We present solar full-disk observations, which were recorded at the Einstein Tower during the years 1943 - 1991 (Solar Cycles 18 - 22). High-school students from Potsdam and Berlin digitized more than 3500 full-disk images during two- to…

Solar and Stellar Astrophysics · Physics 2020-10-07 Partha S. Pal , M. Verma , J. Rendtel , S. J. González Manrique , H. Enke , C. Denker

We analyze the light curves of the recent solar eclipses measured by the Herzberg channel (200-220 nm) of the Large Yield RAdiometer (LYRA) onboard PROBA-2. The measurements allow us to accurately retrieve the center- to-limb variations…

Solar and Stellar Astrophysics · Physics 2015-06-04 A. I. Shapiro , W. Schmutz , M. Dominique , A. V. Shapiro

This is the first in a series of papers presenting methods and results from the Young Solar Analogs Project, which began in 2007. This project monitors both spectroscopically and photometrically a set of 31 young (300 - 1500 Myr) solar-type…

Solar and Stellar Astrophysics · Physics 2015-12-23 R. O. Gray , J. M. Saken , C. J. Corbally , M. M. Briley , R. A. Lambert , V. A. Fuller , I. M. Newsome , M. F. Seeds , Y. Kahvaz

When inverting solar spectra, image degradation effects that are present in the data are usually approximated or not considered. We develop a data reduction method that takes these issues into account and minimizes the resulting errors. By…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 M. van Noort

When cloud layers cover photovoltaic (PV) panels, the amount of power the panels produce fluctuates rapidly. Therefore, to maintain enough energy on a power grid to match demand, utilities companies rely on reserve power sources that…

This paper explores the application of machine learning methods for classifying astronomical sources using photometric data, including normal and emission line galaxies (ELGs; starforming, starburst, AGN, broad line), quasars, and stars. We…

The reconstruction of the solar spectral irradiance (SSI) on various time scales is essential for the understanding of the Earth's climate response to the SSI variability. The driver of the SSI variability is understood to be the intensity…

Solar and Stellar Astrophysics · Physics 2021-09-29 M. Haberreiter , S. Criscuoli , M. Rempel , T. M. D. Pereira

The solar mean magnetic field (SMMF) provided by the Wilcox Solar Observatory (WSO) is compared with the SMMF acquired by the \textit{Helioseismic and Magnetic Imager} (HMI) onboard the \textit{Solar Dynamic Observatory} (SDO). We found…

Solar and Stellar Astrophysics · Physics 2016-08-18 A. S. Kutsenko , V. I. Abramenko

The precise physical process that triggers solar flares is not currently understood. Here we attempt to capture the signature of this mechanism in solar image data of various wavelengths and use these signatures to predict flaring activity.…

Solar and Stellar Astrophysics · Physics 2018-03-14 Eric Jonas , Monica G. Bobra , Vaishaal Shankar , J. Todd Hoeksema , Benjamin Recht

Accurate day-ahead forecasts of solar irradiance are required for the large-scale integration of solar photovoltaic (PV) systems into the power grid. However, current forecasting solutions lack the temporal and spatial resolution required…

Machine Learning · Computer Science 2025-11-07 Baptiste Schubnel , Jelena Simeunović , Corentin Tissier , Pierre-Jean Alet , Rafael E. Carrillo

Full disk observations of the solar chromosphere in the Ca II K line represent a valuable dataset for studies of solar magnetic activity. The S-index is widely used to investigate the magnetic activity of stars, however, its connection to…

Solar and Stellar Astrophysics · Physics 2024-07-08 G. Vanden Broeck , S. Bechet , F. Clette , G. Rauw , K. -P. Schröder , M. Mittag

Unlike other stars, the surface of the Sun can be spatially resolved to a high degree of detail. But the Sun can also be observed as if it was a distant star. The availability of solar disk-resolved and disk-integrated spectra offers an…

Solar and Stellar Astrophysics · Physics 2014-11-27 Alexei Pevtsov , Luca Bertello , Brian Harker , Mark Giampapa , Andrew Marble

Estimates of the photospheric magnetic, electric and plasma velocity fields are essential for studying the dynamics of the solar atmosphere, for example through the derivative quantities of Poynting and relative helicity flux and by using…

Solar and Stellar Astrophysics · Physics 2017-12-18 E. Lumme , J. Pomoell , E. K. J. Kilpua

The accurate prediction of the solar Diffuse Fraction (DF), sometimes called the Diffuse Ratio, is an important topic for solar energy research. In the present study, the current state of Diffuse Irradiance research is discussed and then…

Machine Learning · Computer Science 2020-12-02 Randall Claywell , Laszlo Nadai , Felde Imre , Amir Mosavi

The Astronomical Observatory of the University of Coimbra has a huge collection of solar images, acquired daily since 1926. From the beginning, only spectroheliograms in the CaiiK line has been recorded, and since 1989 in the H_alpha line…

Solar and Stellar Astrophysics · Physics 2020-02-12 S. Carvalho , S. Gomes , T. Barata , A. Lourenco , N. Peixinho

For a "reference day" of minimal solar activity between cycles 23 and 24 we compute the brightness temperature from solar spectral irradiance for each wavelength. We consider small variations of irradiance and temperature about the…

Solar and Stellar Astrophysics · Physics 2022-02-09 Robert F. Cahalan , Paulino Ajiquichi , Gaspar Yataz

We present a comparison of two methods of fitting solar-like variability to increase the efficiency of detection of Earth-like planetary transits across the disk of a Sun-like star. One of them is the harmonic fitting method that coupled…

Astrophysics · Physics 2009-11-13 A. S. Bonomo , A. F. Lanza

A solar active region can significantly disrupt the Sun Earth space environment, often leading to severe space weather events such as solar flares and coronal mass ejections. As a consequence, the automatic classification of active region…

Solar and Stellar Astrophysics · Physics 2024-10-24 Edoardo Legnaro , Sabrina Guastavino , Michele Piana , Anna Maria Massone

Flares are a well-studied aspect of the Sun's magnetic activity. Detecting and classifying solar flares can inform the analysis of contamination caused by stellar flares in exoplanet transmission spectra. In this paper, we present a…

Solar and Stellar Astrophysics · Physics 2024-06-25 Nicole Hao , Laura Flagg , Ray Jayawardhana

Solar energy is now the cheapest form of electricity in history. Unfortunately, significantly increasing the grid's fraction of solar energy remains challenging due to its variability, which makes balancing electricity's supply and demand…

Machine Learning · Computer Science 2021-12-30 Akansha Singh Bansal , Trapit Bansal , David Irwin