A new systematic study of the atmospheric conditions at the Muztagh Station in western China has revealed the site's unique suitability for optical observations. Researchers from the Xinjiang Astronomical Observatory of the Chinese Academy of Sciences reported that the location offers excellent "seeing" conditions, making it ideal for high-precision optical observations.

The findings were published in the Monthly Notices of the Royal Astronomical Society.

As starlight travels through the Earth's atmosphere, it is affected by optical turbulence, which causes fluctuations in the refractive index and distorts the optical wavefront, thereby degrading a telescope's imaging quality. "Seeing" reflects the degree to which stellar images are blurred and jittered by atmospheric optical turbulence, and is one of the core indicators used to evaluate the quality of an observatory site. 

The study, led by PhD candidate GU Wenbo with his advisor Prof. Ali Esamdin and colleagues analyzed seeing and meteorological data collected from 2018 to 2024 at the station's North-1 and North-2 points. Using a Differential Image Motion Monitor (DIMM), a 30-meter meteorological tower, and a PC-4A automatic weather system, the researchers measured key parameters for the Muztagh Observatory, including seeing, temperature, wind speed, and wind direction.

Results show that the seeing conditions at the Muztagh Station are excellent. The median seeing is 0.78 arcseconds at the North-2 point at a height of 10 meters, and 0.89 arcseconds at the North-1 point at a height of 6 meters. Simultaneously, the site has a small nighttime ground-surface temperature difference (about 2°C), moderate wind speed (median value of 5–6 m/s), and a stable, dominant wind direction (southwest).

The researchers also examined the relationship between wind dynamics and optical clarity. They found a significant "U-shaped" correlation between seeing and wind speed, where moderate wind speeds are most favorable for suppressing atmospheric turbulence and optimizing seeing. Airflow from the dominant wind direction usually brings better seeing, whereas strong vertical wind shear and short-term, drastic fluctuations in wind speed will significantly enhance atmospheric turbulence, leading to a deterioration in seeing.

With its excellent near-ground turbulence environment and seeing conditions, the Muztagh Station shows great potential to become an outstanding optical astronomical observatory site in western China.

This study was funded by a project from the National Natural Science Foundation of China.