High resolution imaging of strong solar flares from ground based telescopes is hard to secure because major eruptions often occur on the far side of the Sun, during local night, in poor weather, or just outside the instrument field of view. Prof. Carsten Denker, head of the Solar Physics section at the Leibniz Institute for Astrophysics Potsdam (AIP), described how the campaign with the 1.5 meter GREGOR telescope at Teide Observatory in Spain captured the development of X class flares on 10 and 11 November 2025.[1]
During its transit across the visible solar disk, active region NOAA 14274 produced 135 C class, 15 M class, and 5 X class flares, making it the most active region of 2025 and a key contributor to Solar Cycle 25. X class events mark the top of the standard X ray flare scale, with each step in the classification corresponding to a factor of ten in X ray output. The X5.1 flare on 11 November 2025 ranks as the sixth most energetic event of the current cycle, and both X class eruptions on 10 and 11 November were associated with rapid coronal mass ejections that drove strong auroral displays.[1]
To map the full extent of NOAA 14274, the observers used four fast cameras on the upgraded High resolution Fast Imager at GREGOR to scan a grid of 7 by 4 pointings across the active region in about 14 minutes, covering an area roughly 175,000 kilometers by 110,000 kilometers on the solar surface. This observing mode, tested for the first time on a large and complex region with many sunspots, produced 28 mosaic tiles that were later processed with image restoration techniques to recover fine sunspot and penumbral structure. An X1.2 flare erupted about half an hour after the raster scan, and signatures of the flare precursors were already visible in the data.[1]
The restored images show penumbral fibrils that are strongly curved and intertwined rather than radially aligned, a pattern that indicates a highly stressed magnetic field configuration. Sunspot rotation and shear motions in the region created conditions in which magnetic energy could accumulate and then release explosively, with the energy release starting in penumbral filaments on spatial scales close to GREGORs resolving power of about 100 kilometers on the solar surface.[1]
Over the November 2025 observing run, the campaign collected nearly 40,000 datasets for subsequent processing and analysis. A first subset of high resolution images has been presented in a Research Note of the AAS to demonstrate the quality of the dataset and to outline the scientific questions that future studies will address.[1]
Research Report:The Calm before the Storm: High Spatial Resolution Mosaic of Active Region NOAA 14274 at the Onset of an X1.2 Flare
Related Links
Leibniz Institute for Astrophysics Potsdam (AIP)
Solar Science News at SpaceDaily
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
