(Photo: Privat/YNAO)
Gerhard Samulat

China Gazes into Space

The Lijiang Telescope is the world’s largest automatically controlled eye looking into the sky. Zerodur® glass ceramic from SCHOTT is used as the mirror substrate.

Li Yan, Director of the Yunnan Astronomical Observatory located in the southwest of the People’s Republic of China, celebrated the inauguration of what is now Asia’s largest optical telescope. It is based near the city of Lijiang that has a population of over a million. The telescope is located on top of a 3,240-meter high peak in the Yulong Mountains, which the locals also refer to as ”the jade dragon”, because of its prominent shape.

With regard to the substrate material for the main mirror, the Chinese decided to use the very same material that most other modern observatory operators rely on, Zerodur® glass ceramic from SCHOTT. Its most important characteristic is that this mirror substrate material does not change its shape noticeably, even when temperatures shift considerably. This is extremely important for telescopes to provide undistorted images. In addition, the material developed by SCHOTT is characterized by excellent homogeneity and high chemical resistance. It is easy to process and excellent when it comes to polishing. As a result, it offers all of the features that professional astronomical mirror substrates require.
With a mirror diameter of 2.45 meters, the telescope in China forays into a new class with respect to size. (Photo: SCHOTT/J.Siefke)
”The Lijiang Telescope is state of the art and can deliver both photographic and spectroscopic images from within both the visible and the invisible spectral region,” Li Yan explains. With a diameter of 2.45 meters, the mirror substrate is more than double the size of the 1-meter telescopes that are predominant in China.
Inauguration of the Lijiang Telescope is a prelude for the realization of other ambitious Chinese astronomy projects. (Photo: SCHOTT/J.Siefke)
This sky scout was designed and built by the British company Telescope Technologies Limited (TTL) at a cost of around three million euros and now ranks as the world’s largest fully automatic robotic telescope. It is unique as it is not only capable of following objects very closely on its own for longer periods of time, but can also be operated remotely and is therefore capable of reacting immediately to capture sudden, surprising cosmic events, such as exploding stars. With the help of their new viewing device, researchers are going to determine the age of cosmic structures and to discover new planets, stars and galaxies.

The Lijiang Telescope is the first of seven national astronomy programs that China is currently pursuing. With the help of the Large Sky Area Multi-Objects Fiber Spectroscopy Telescope (LAMOST) that will go into operation early next year at the Xinglong Observatory in the Hebei Province in the north of China, the People’s Republic is seeking to join the world’s elite in the field of astrophysics. SCHOTT has already supplied forty hexagonal mirror substrates with one meter in the diagonals made from Zerodur® glass ceramic for this device. The LAMOST Telescope is designed to provide up to 4,000 spectra of stars simultaneously.