2022/11/24 by Yoichiro Hanaoka, Hanaoka, Yoichiro
Computer Science · Physics and Astronomy · #FOS: Electrical engineering #FOS: Physical sciences #Image and Video Processing (eess.IV) #Solar Radiation and Photovoltaics #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR) #electronic engineering #information engineering
paper · pdf · doi:10.48550/arxiv.2211.13552
openalex publication_date 2022/11/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We developed an automated method for sunspot detection using digital white-light solar images to achieve a performance similar to that of visual drawing observations in sunspot counting. To identify down to small, isolated spots correctly, we pay special attention to the accurate derivation of the quiet-disk component of the Sun, which is used as a reference to identify sunspots using a threshold. This threshold is determined using an adaptive method to process images obtained under various conditions. To eliminate the seeing effect, our method can process multiple images taken within a short time. We applied the developed method to digital images captured at three sites and compared the detection results with those of visual observations. We conclude that the proposed sunspot detection method has a similar performance to that of visual observation. This method can be widely used by public observatories and amateurs as well as professional observatories as an alternative to hand-drawn visual observation for sunspot counting.