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The SWAP Filter: A Simple Azimuthally Varying Radial Filter for Wide-Field EUV Solar Images
Berghmans, David; Rachmeler, Laurel A.; West, Matthew J. +5 more
We present the SWAP Filter: an azimuthally varying, radial normalizing filter specifically developed for EUV images of the solar corona, named for the Sun Watcher with Active Pixels and Image Processing (SWAP) instrument on the Project for On-Board Autonomy 2 (PROBA2) spacecraft. We discuss the origins of our technique, its implementation and key …
Cyclical Behaviors of Sunspot-Group Tilt Angles in Solar Cycles 21 - 23
Gao, Peng-Xin
Based on the Debrecen Photoheliographic Data (DPD) sunspot catalog, we investigate the cyclical behaviors of tilt angles of all sunspot groups (SGs) and SGs with angular separation constraint S >2.5∘ in Solar Cycles (SCs) 21 - 23. It is found that, the cyclical behaviors of tilt angles during SC 23 are different from those of SCs 21 …
Explosive Events in the Quiet Sun Near and Beyond the Solar Limb Observed with the Interface Region Imaging Spectrograph (IRIS)
Vial, J. -C.; Alissandrakis, C. E.
We study point-like explosive events (EE), characterized by emission in the far wings of spectral lines, in a quiet region near the South Pole, using Interface Region Imaging Spectrograph (IRIS) spectra at two slit positions, slit-jaw (SJ) observations, and Atmospheric Imaging Assembly (AIA) images. The events were best visible in Si IV spectra; t…
On the Periodicities in Solar Rotation and Activity Determined from Sunspot-Group Data and Possible Connection with Rossby-Like Waves
Hanslmeier, Arnold; Ruždjak, Domagoj; Brajša, Roman +2 more
Analyses of solar rotation and activity, and their variations, can improve the understanding of the formation and interaction of the solar-activity bands and therefore give important observational constraints on the modelling of the solar dynamo and improve the forecast capability in solar activity and space weather. Sunspot-position data obtained…
The Solar Ultra-Violet Imaging Telescope (SUIT) Onboard Intelligence for Flare Observations
Tripathi, Durgesh; Tyagi, Anurag; Sankarasubramanian, K. +14 more
Aditya-L1 is India's first observatory-class solar space mission to study the Sun from the Lagrange L1 point. The Solar Ultra-Violet Imaging Telescope (SUIT) is one of the payloads onboard Aditya-L1. SUIT is an off-axis Ritchey-Chrétien (RC) telescope, which images the Sun onto a 4k×4k CCD covering a field-of-view of 1.5 R⊙ w…
Behaviour of 27-Day and 13.5-Day Periodicities in Galactic Cosmic Particles as Observed by Spacecraft and Neutron Monitors During Different Solar Polarity Cycles
Kotzé, Pieter
An analysis has been made of the behaviour of the 27-day and 13.5-day periodicities in proton, C, and O galactic-cosmic-ray (GCR) particles at different energies as observed by the Advanced Composition Explorer (ACE) and SOHO (Solar and Heliospheric Observatory) spacecraft during both Solar Cycles 23 and 24. In addition, the behaviour of the 27-da…
Eruptive Flare, CME, and Shock Wave in the 25 August 2001 High-Energy Solar Event
Grechnev, V. V.; Kochanov, A. A.; Uralov, A. M.
The major SOL2001-08-25 event produced a fast coronal mass ejection (CME: 1430 km s−1), strong flare emissions in hard X-rays and γ -rays extending to high energies, and neutrons detected both on spacecraft and by a low-latitude neutron monitor. To supplement the probable picture of this outstanding event, we reconstruct kinematic plots…
A Machine Learning Enhanced Approach for Automated Sunquake Detection in Acoustic Emission Maps
Besliu-Ionescu, Diana; Mercea, Vanessa; Paraschiv, Alin Razvan +2 more
Sunquakes are seismic emissions visible on the solar surface, associated with some solar flares. Although discovered in 1998, they have only recently become a more commonly detected phenomenon. Despite the availability of several manual detection guidelines, to our knowledge, the astrophysical data produced for sunquakes is new to the field of mac…
Small-Scale Upflows in a Coronal Hole - Tracked from the Photosphere to the Corona
Barczynski, Krzysztof; Orozco Suárez, David; Mandrini, Cristina H. +4 more
Coronal transients are known as sources of coronal upflows. With the commissioning of Solar Orbiter, it became apparent that coronal small-scale features are even more frequent than previously estimated. It was found that even small coronal features seen by Solar Orbiter can produce visible upflows. Therefore, it is important to study the plasma f…
Three Eruptions Observed by Remote Sensing Instruments Onboard Solar Orbiter
Susino, Roberto; Romoli, Marco; Andretta, Vincenzo +31 more
On February 21 and March 21 - 22, 2021, the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter observed three prominence eruptions. The eruptions were associated with coronal mass ejections (CMEs) observed by Metis, Solar Orbiter's coronagraph. All three eruptions were also observed by instruments onboard the Solar-TErrestrial RElations Observ…