Automatic Recognition of Sunspots in HSOS Full-Disk Solar Images. (11th May 2016)

• Record Type: Journal Article
• Authors: Zhao, Cui; Lin, GangHua; Deng, YuanYong; Yang, Xiao
• Is Part Of: Publications of the Astronomical Society of Australia. Volume 33(2016)
• Publication Date: 2016-05-11
• Subjects: activity – data analysis – image processing – sunspot; Astronomy -- Periodicals; Southern sky (Astronomy) -- Periodicals; Astrophysics -- Periodicals; Periodicals; 520.5
• DOI: 10.1017/pasa.2016.17
• Languages: English
• ISSNs: 1323-3580

Abstract

Abstract: A procedure is introduced to recognise sunspots automatically in solar full-disk photosphere images obtained from Huairou Solar Observing Station, National Astronomical Observatories of China. The images are first pre-processed through Gaussian algorithm. Sunspots are then recognised by the morphological Bot-hat operation and Otsu threshold. Wrong selection of sunspots is eliminated by a criterion of sunspot properties. Besides, in order to calculate the sunspots areas and the solar centre, the solar limb is extracted by a procedure using morphological closing and erosion operations and setting an adaptive threshold. Results of sunspot recognition reveal that the number of the sunspots detected by our procedure has a quite good agreement with the manual method. The sunspot recognition rate is 95% and error rate is 1.2%. The sunspot areas calculated by our method have high correlation (95%) with the area data from the United States Air Force/National Oceanic and Atmospheric Administration (USAF/NOAA).