From January 24th to 27th, 2021, Wang Xiqin, Executive Vice President of Tsinghua University, Mao Shude, Cai Zheng, Huang Lei from the Department of Astronomy and Precision Instruments, as well as representatives from the Research Institute, Laboratory Department, and Domestic Cooperation Office, went to the Saishitengshan area of Lenghu Town, Qinghai Province for on-site investigation. The members of the inspection team conducted a comprehensive investigation and research on the local geographical conditions, natural conditions, engineering conditions, transportation conditions, supporting conditions, progress of similar projects, and cooperation conditions, and had detailed discussions with the Qinghai Provincial Government on the cooperation status of the project.
Lenghu Town: located in Saishiteng Mountain area, Mangya City, Haixi Prefecture, Qinghai Province, at the junction of Qinghai, Xinjiang, and Gansu provinces, 944 kilometers away from the provincial capital Xining, 430 kilometers from Delingha, and 230 kilometers from Dunhuang, with an average elevation of 2700 meters.
Regional Plan: To build the largest astronomical observation base, astronomical technology industry base, and cultural tourism industry base in the northern hemisphere, with science and technology projects as the core.
Saishiteng Mountain, Lenghu Town: located in the northwestern part of Qinghai province, bordering Qinghai, Xinjiang and Gansu provinces. It is 944 km from the provincial capital of Xining, 430 km from Delingha, and 230 km from Dunhuang. The average altitude is 2700 meters.
Coordinates: 93.895278E 38.606944N， Altitude: ranges from 4300 to 4500 meters. Conditions: After more than three years of on-site surveying, experimental observations, historical data analysis, it was found that the Saishiteng Mountain area in Lenghu Town has excellent sky conditions, high atmospheric transparency, and stable weather, making it a potential world-class astronomical observatory site.
The observation project at 3800 meters and 4200 meters has been underway for more than two years. The conditions here are not much different from those of top international observatories, slightly better than the Kitt Peak National Observatory in Arizona, USA, but slightly worse than the top observatories in Chile and Hawaii. Meteorological conditions:
Temperature: The annual average temperature is 2-3℃, with large temperature differences between day and night. The extreme highest temperature is 34.2℃, and the extreme lowest temperature is -34.3℃. Wind: The prevailing winds are from the west or northwest, with an annual average of 6.8 m/s. The median wind speed at the 4200-meter peak is around 5-6m/s. Cloud: The annual cloud cover is about 30%. Precipitation: The annual precipitation is 17 millimeters. Light and atmosphere: Seeing: The median value is 0.77 arcseconds. Sky brightness: 22 mag/arcsec2. Aerosol optical depth: 0.21. Artificial lighting: 0. Engineering and geological conditions: There is a six-month construction period every year, and the foundation is made of granite rock.
After this site survey, the following information was obtained: 1) the geographic conditions can basically meet the requirements for the construction, operation, and maintenance of scientific research facilities, as well as the basic living needs of scientific research and operation and maintenance personnel; 2) the preliminary assessment of the natural environment can basically meet the requirements for the construction of this project, and it is a top-quality observation site in China; 3) the local government actively promotes the development of the astronomical industry, and the policy formulation and regional planning meet the basic requirements for the construction and long-term operation of this project. The above provides a theoretical basis for further determining the site and carrying out the project.