BEIJING.- The Spectral Imaging CoronaGraph (SICG) obtained its first coronal image on October 25, 2023, marking the completion of China's first independently developed normalized operational ground-based coronagraph.

SICG, located at the Lijiang Yulong Astronomical Observatory of the Chinese Academy of Sciences with an altitude of 3200 meters, is part of the National Major Science and Technology Infrastructure "Meridian Space Weather Monitoring Project" (Chinese Meridian Project). It is jointly developed by Shandong University, Changchun Institute of Optics, Fin Mechanics and Physics of the Chinese Academy of Sciences (CAS), Nanjing Institute of Astronomical Optics and Technology of CAS and Yunnan Observatory of CAS.

SICG adopts an internally occulting refractive optical system with an objective aperture of 220 mm and an observation field of 1.05 Rs to 2.00 Rs (Rs is the solar radius). It can provide observations of the coronal red line and green line.

Due to the weak detection signal of the coronal instrument (the coronal signal intensity is one millionth of that of the sun) and the difficulty in suppressing stray light, the development of optical and mechanical systems is extremely difficult. The research team led by ZHANG Hongxin from the Changchun Institute of Optics, Precision Mechanics and Physics has undertaken the development of the SICG coronagraph optical imaging system. This team is the first scientific research team in China to conduct coronagraph research, and they overcame these difficulties and completed the system development on time.