Abstract
On Earth’s surface, there are only a handful of high-quality astronomical sites that meet the requirements for very large next-generation facilities. In the context of scientific opportunities in time-domain astronomy, a good site on the Tibetan Plateau will bridge the longitudinal gap between the known best sites1,2 (all in the Western Hemisphere). The Tibetan Plateau is the highest plateau on Earth, with an average elevation of over 4,000 metres, and thus potentially provides very good opportunities for astronomy and particle astrophysics3–5. Here we report the results of three years of monitoring of testing an area at a local summit on Saishiteng Mountain near Lenghu Town in Qinghai Province. The altitudes of the potential locations are between 4,200 and 4,500 metres. An area of over 100,000 square kilometres surrounding Lenghu Town has a lower altitude of below 3,000 metres, with an extremely arid climate and unusually clear local sky (day and night)6. Of the nights at the site, 70 per cent have clear, photometric conditions, with a median seeing of 0.75 arcseconds. The median night temperature variation is only 2.4 degrees Celsius, indicating very stable local surface air. The precipitable water vapour is lower than 2 millimetres for 55 per cent of the night.
Highlights
For any modern observatories for night optical/infrared astronomy and planetary sciences[9], the first factor to consider is undoubtedly the clarity of nights, followed by the darkness of the night sky, among other parameters important for advanced modes of observations
Qinghai Province on the Tibetan Plateau has a very low population; problematic artificial light sources are at present non-existent
If the local population were to grow with economic development, control of light pollution could be lost
Summary
Licai Deng1,2,3 ✉, Fan Yang1,2 ✉, Xiaodian Chen1,2,3 ✉, Fei He4,5 ✉, Qili Liu[6], Bo Zhang[1], Chunguang Zhang[1,2,3], Kun Wang[2], Nian Liu[2], Anbing Ren[2], Zhiquan Luo[2], Zhengzhou Yan[2], Jianfeng Tian1 & Jun Pan[1]. The main site parameters—including cloudiness and night-sky background brightness, air temperature, pressure, humidity, wind speed and direction, dust, precipitable water vapour (PWV), and, most importantly, seeing (using a differential image motion monitor (DIMM)7,8)—have been monitored starting at different times from March 2018 onwards (summarized in Extended Data Table 1). After the initial site reconnaissance, to start the site monitoring as soon as possible, the building materials and tools were carried to the site by a helicopter and the scientific devices were manually carried up to the mountain in September 2018, before the road reached the site This could not have been accomplished without the great assistance from the local government of Lenghu Town.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
