On October 25, 2023, the spectral imaging coronagraph of the national major scientific and technological infrastructure "Ground-based Comprehensive Monitoring Network for Space Environment" (Phase II of the Chinese Meridian Project) successfully passed the process testing organized by relevant departments at the Yulong Station in Lijiang, and obtained the first batch of coronal observation images, marking the completion of the first independently-developed ground-based coronagraph in China for normal operation.
The Spectral Imaging Coronagraph (SICG) of the Phase II of the Chinese Meridian Project was installed in the park of Lijiang Astronomical Observatory of Yunnan Observatory of the Chinese Academy of Sciences at an altitude of 3200 meters.
The development and construction of SICG was led by Shandong University, with Prof. Lidong Xia of the Institute of Space Sciences/School of Space Science and Physics of Shandong University serving as the chief scientist.
The Multi-band Coronagraph Filters and Equatorial Mounts Research Group of the Nanjing Institute of Astronomical Optics & Technology, Chinese Academy of Sciences, has been mainly responsible for the development of the dual-band birefringent filter (which is the core equipment of the coronagraph), the small and lightweight chromospheric birefringent filter, the chromospheric telescope, and the precision-tracking equatorial mount.
The dual-band birefringent filter operates in the bands of coronal red line (Fe X 6374 Å/FWHM 1 Å) and the coronal green line (Fe XIV 5303 Å/FWHM 0.67 Å), and can switch operating wavelengths and operate at any wavelength within the range of ±5Å .
The successful development of the small and lightweight chromospheric birefringent filter (Hα 6563 Å/FWHM 0.5 Å) has made lightweight solar chromospheric telescopes and data specialization a reality.
The solar chromospheric telescope (clear aperture 142 mm) developed by the research group, which allows the high-quality observation of the full disk, was mounted on the equatorial mount side by side with the coronagraph.
This expands the capabilities of the coronagraph, allowing it to observe both the corona and the full disk, which is significant for scientific research and space weather forecasting. The equatorial mount can be guided by calculating the coordinate center of the chromospheric full-disk image, which improves the tracking accuracy of the equatorial mount and lays the foundation for the operationalization of the instrument.
The delivered equatorial mount adopts DC servo drive to reduce transmission chain errors, and all parameters meet or exceed the contract requirements.
After obtaining the first batch of coronal observation images by the Coronagraph Project Group of Shandong University, the scientific data have been assessed by experts that the quality of the observations by SICG has reached the international first-class level, making it one of the most excellent ground-based coronagraphs working in these bands internationally.
The SICG is an important component of the solar-interplanetary monitoring chain subsystem of the Phase II of the Chinese Meridian Project, and is also an important part of the full chain monitoring of solar-terrestrial space.
In the next step, the Multi-band Coronagraph Filters and Equatorial Mounts Research Group of the Nanjing Institute of Astronomical Optics & Technology will continue to carry out joint commissioning and testing to make the instrument work in the best condition, so as to be fully prepared for the delivery, acceptance, and formal trial operation in 2024.
Related link:
The spectral imaging coronagraph of the national major scientific and technological infrastructure "Ground-based Comprehensive Monitoring Network for Space Environment" (Phase II of the Chinese Meridian Project) successfully passed the process testing :https://new.meridianproject.ac.cn/gcdt/info/2023/1818.html
