Full-disc observations of the Sun in the Ca ii K line provide one of the longest collections of
solar data. First such observations were made in 1892 and since then various sites around …

We present the final Sloan Digital Sky Survey IV (SDSS-IV) quasar catalog from Data
Release 16 of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). This catalog …

With the increasing concern about climate change, it is important to have accurate
information on the individual contributions by the potential driving agents, solar variability …

Context. Investigating the early-stage evolution of an erupting flux rope from the Sun is
important for understanding the mechanisms of how it loses its stability and its space …

Context. Constructing the relevant magnetic field lines from active region modelling data is
crucial to understanding the underlying instability mechanisms that trigger the …

Solar activity has been subject to increasingly more research in the last decades. Its
influence on life on Earth is now better understood. Solar winds impact the earth's magnetic …

Context. Studies of long-term solar activity and variability require knowledge of the past
evolution of the solar surface magnetism. The archives of full-disc Ca II K observations that …

A huge collection of solar images to visualize sunspot are acquired by various solar
observatories spread across the globe. This necessitates efficient tools for detecting and …

Abstract In 2020, the Geophysical and Astronomical Observatory of the University of
Coimbra will celebrate the 95th anniversary of its first spectroheliographic observation …

A new software (Soonspot) for the determination of the heliographic coordinates and areas
of sunspots from solar images is presented. This program is very user-friendly and the …