The research team from Nanjing Institute of Astronomical Optics and Technology of Chinese Academy of Sciences (NIAOT) has developed a novel method utilizing the LAMOST (Guo Shoujing Telescope) guiding camera data to assess the impact of satellites on ground-based astronomical observatories.
The evaluation of major global observatories reveals that facilities near the equator currently face the most severe satellite interference. Observatories located at latitudes of ±50 degrees and ±80 degrees experience the most significant impact from low Earth orbit satellites.
Since the introduction of the 66-satellite Iridium constellation in 1997, numerous satellite constellations have been proposed, culminating in the Starlink and OneWeb systems. As of December 16, 2024, Starlink alone has over 6,800 satellites operational, with projections indicating a total of 100,000 low Earth orbit satellites by 2035.
Notably, the Starlink satellites can achieve a visual magnitude of 7.1 when reflecting sunlight, while the massive BlueWalker satellites reach a brightness of magnitude 0.2. Both space-based telescopes like the Hubble Telescope and ground-based facilities such as the VLT (Very Large Telescope) have reported satellite interference affecting astronomical imaging data, compromising photometric measurements, damaging spectral and imaging data, and increasing sky background brightness.
Assessing the impact of satellites on different observatories aids in determining the current severity of satellite interference on astronomical observations. It will become a critical factor in evaluating observatory conditions.
Previous assessment models assumed uniform satellite distribution or circular orbits. This research team used Two Line Element (TLE) satellite data to construct elliptical orbit models, deriving probability density distributions at different geographic coordinates, thereby enhancing the precision and reliability of the results.
Dr. Tianzhu Hu is the first author, with Associate Prof. Yong Zhang and Academician Xiangqun Cui as corresponding authors. The study received assistance from Dr. Tuanrui Sun at Purple Mountain Observatory and was supported by the National Natural Science Foundation and the Jiangsu Natural Science Foundation.
Figure 1: Number of observable low Earth orbit satellites at different sites (based on September 2023 data). The upper figure shows the integral result of low Earth orbit satellite probability density within the elevation angle range of 60-90 degrees at the observation site, and the lower figure shows the integral result of low Earth orbit satellite probability density within the elevation angle range of 30-90 degrees at the observation site.
DOI: https://doi.org/10.1051/0004-6361/202349048
