Automatic detection process of solar active region based on SDO/AIA digital image

Abstract

Abstract The aim of this study is to do automatic detection of the sunspot on the solar disc using MATLAB. The digital images from the satellite SDO (Solar Dynamic Observatory)/AIA (Atmospheric Imaging Assembly) with 512 x 512 pixels jpg image were being processed through several steps: segmentation threshold to separate the object from its background and obtain the area and coordinate points (centroids) of the sunspots. Then, the sunspot coordinates gained from the automatic detection are compared with the coordinates released by NASA at solarmonitor.org. The error calculation using RMSE gives 30.824022 “to 1120.2831” for horizontal position and 46.509763 “to 266.74988” for vertical position. The errors are still considered significant since Lembaga Penerbangan dan Antariksa Nasional (LAPAN, Indonesian National Institute of Aeronautics and Space) specify the error tolerance value of 20” maximum. The main factor for the difference is the spatial characteristics of the EUV images used for automatic detection are different with the characteristics of the photosphere image used by solarmonitor.org as the catalogue reference of the sunspots.