On the surface of the Earth, there are only a handful of locations that meet the requirements for the installation of large telescopes dedicated to professional astronomical observation.
Among these sites are the Chilean Atacama Desert, where the European Southern Observatory (ESO) has its telescopes; the mountains of Hawaii, such as Mauna Kea (USA), and the peaks of the Canary Island of La Palma, which are home to the Roque de los Muchachos Observatory. All these places have in common that they are located in the western hemisphere of the Earth.
Now, a team of Chinese astronomers has proposed, in an article published in the journal Nature, a new observation zone in the eastern hemisphere: the tibetan plateau. Specifically, the vicinity of the small town of Lenghu, belonging to Qinghai province. With an average height of 4,000 meters, the Tibetan Plateau is the highest plateau on the planet, which has earned it the nickname ‘the roof of the world‘.
Lenghu’s environment has characteristics that make it ideal for astronomy, such as a dark sky, which allows a deeper vision, as well as little presence of water vapor, which favors infrared observation.
Lenghu’s environment brings together a series of characteristics that make it ideal for astronomy, such as “a dark sky, which allows a deeper vision, as well as little presence of precipitable water vapor, which favors infrared observation”, he highlights. to SINC the main author, Licai Deng, an astronomer at the Chinese Academy of Sciences.
“Being in East Asia – he adds -, save the enormous geographical distance between the observatories of Hawaii and the Canary Islands, which is very promising for the search for transient astronomical phenomena ”.
After three years researching and measuring various parameters in the Saishiteng mountain near Lenghu, they have found potential places for astronomical observation located between 4,200 and 4,500 m – the higher the altitude, the lower the atmosphere, and therefore the clearer the observation -, with an average of nights without cloudiness around to the 70%.
Other relevant parameters of the quality of your sky is his brightness (22 mag arcsec2), a good mean seeing (0.75 arcsec, a key parameter to describe the blurring of stars due to atmospheric turbulence) and measurements of water steam precipitable less than 2 mm during 55% of the night.
Comparison of sky quality parameters in the Lenghu environment and that of the most important observatories in the world. Some relevant thresholds are, for example, an average ‘seeing’ less than 1 and a sky brightness greater than 21.4 mag / arcsec2. / L. Deng et al./Nature
When determining the suitability of a location to install an observatory, it is necessary to analyze a series of factors, such as the “optical quality of the atmosphere, the meteorological stability of the place and its seismicity, but also the logistical and social problems that could lead to the construction of a telescope ”, points out Antonia varela, from the Instituto de Astrofísica de Canarias (IAC).
An example of the social conflicts that may arise is the future Thirty Meter Telescope (TMT), whose planned location was Mauna Kea in Hawaii, but this mountain is considered sacred by the natives and they have stopped the project. As an alternative location is the island of La Palma, although a Canarian court has also overturned its building permit. So far no problems of this kind have arisen in China.
Sky quality like on La Palma
According to the results of the study, the location proposed by the researchers in Lenghu “seems promising, at a level comparable to other large observatories such as the canaries,” he says. Julio Castro Almazán, of the sky quality group of the IAC.
“One of the problems that often accompany Tibetan sites is that they are not free from monsoon activity, so the water vapor data during the summer is a bit worse than what you would expect for height. In any case – he emphasizes – it seems an excellent place ”.
This year an agreement was signed to build a 6.5-meter telescope here, among others, and in the future the large Chinese telescope of more than 12 meters will also come.
Licai Deng (Chinese Academy of Sciences)
The so-called Lenghu Observatory It is already in the process of construction, since “several Chinese institutions that had plans to build a telescope have decided to do it here after knowing our results,” explains Deng.
“The telescope 50BiN for the study of clusters had its first observation in December 2020, “says the researcher,” and others are to come, some already under construction: a 6.5 m telescope (the agreement was signed last May), another for 2.5 m spectroscopy, a survey telescope for images, the Chinese telescope of the SONG network (another Danish one is in Tenerife), a 1 m infrared solar telescope, a planetary research platform and an array to detect near-Earth objects (NEO) ”.
“In the future there will also come the great Chinese telescope over 12 meters and an updated version of LAMOST (currently located in eastern China) ”, advances the astronomer.
According to Deng, the conclusions of the work have been very well received by the Chinese authorities, and they expect great support from the central and regional government at all levels: “The development of an observation site like Lenghu is very exciting for the community. astronomical, both domestic and international ”.
Licai Deng et al “Lenghu on the Tibetan Plateau as an astronomical observing site”. Nature, 2021
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