Abstract
Extracting accurate star centroids in the observed star images is one of the key problems for image navigation of the geosynchronous interferometric infrared sounder (GIIRS) of Fengyun-4A Satellite (FY-4A), the first scientific experimental satellite of the new generation of Chinese geostationary meteorological satellite Fengyun-4 series. Compared with star sensors which are widely used for star observation, it is challenging to detect the $2\times 2$ star spot from the focused star images of GIIRS and calculate the star centroid in high precision. In this paper, we propose a star detection and centroiding method based on trajectory search and trajectory fitting. Since the launch of FY-4A in December 2016, our centroiding method has been tested in-orbit for over two years. The extensive experiments show that the star centroiding error of our method is less than 0.3 pixels, which makes an important contribution to image navigation of FY-4A.
Highlights
Fengyun-4 (FY-4) is the new generation of geostationary meteorological satellite developed by China [1]–[3]
Four new instruments are aboard FY-4A [1], [4] to generate remote sensing products, including Advanced Geosynchronous Radiation Imager (AGRI), the Geosynchronous Interferometric Infrared
Image navigation is a key problem for meteorological satellite, since it makes a direct influence on the quality of remote sensing products [5]
Summary
Fengyun-4 (FY-4) is the new generation of geostationary meteorological satellite developed by China [1]–[3]. The predicted star to be sensed for image navigation should be distinguished from others before star centroiding. Overall, these characteristics make it a challenge to detect stars and calculate their centroids in high precision for GIIRS. Aiming to solve the problems, this paper proposes a star detection and centroiding method for GIIRS aboard FY-4A. Experimental results on simulated star images in various conditions and real star sensing images of in-orbit testing of FY-4A validate the feasibility and effectiveness of our method for robust star detection and accurate centroiding of GIIRS aboard FY-4A. C. FLOWCHART OF STAR DETECTION AND CENTROIDING The star sensing image processing for GIIRS aims to solve two problems. Details of the proposed method will be introduced
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