Article Posted on : - Nov 13, 2008

Installing MA sub-mirror. File photo from official site

HONG KONG (BNS): China has built the world's most powerful optical telescope with an aim to have a clearer view of the universe.

 
The Chinese Academy of Sciences has built the telescope in a research base of the National Astronomical Observatories. The advanced astronomical facility has an aperture of over four meters and 4000 optical fibers which can track space and decode starlight into spectrographic data.

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has a much longer range than the previous biggest, the Sloan Digital Sky Survey.

Prof Cui Xiangqun, head of the Chinese Academy of Sciences Nanjing Institute of Astronomical Optics and Technology, said that LAMOST's large, clear aperture and wide field of view gives it a distinct edge.

"We need to change the shape of the reflecting mirror during tracking in order to eliminate the spherical aberration of the primary mirror for more precise recording of spectra," Cui said.

A four meter segmented reflecting mirror was mounted at the lower end of the building. During observation nights, the upper part of the dome is removed and the starlight gets reflected from the lower mirror up through the 20-meter tube to a 6 meter primary mirror.

Then the light of space is fed into the front ends of optical fibers accurately positioned on a focal plane, before real-time data are recorded into spectrographs fixed in a room underneath.

"A key innovation is an active optics system that deforms the correcting mirror's 24 plates individually, compensating for the spherical aberration of the primary mirror and bringing both mirrors into focus simultaneously," Cui said.

The Chinese team of engineers designed 24 honeycomb shaped flat thin plates as a reflecting mirror. The bigger primary mirror comprises 37 spherical hexagonal cells.

The big telescope marks another feather in the cap of Chinese scientists who are setting their own agenda after achieving big feats. The Chinese space missions have already created a stir in the world. The success of manned missions to space has forced the world to stand up and take note of Beijing's scientific prowess. The officials said the new telescope is also a step in that direction.

The scientific goal of LAMOST focuses on the extragalactic observation, structure and evolution of the Galaxy, and multi-wave identification. The spectroscopic survey carried out by LAMOST of tens of millions of galaxies and others will make substantial contribution to the study of extra-galactic astrophysics and cosmology, such as galaxies, quasars and the large-scale structure of the universe. Its spectroscopic survey of large number of stars will make substantial contribution to the study of stellar astrophysics and Galaxy. Its spectroscopic survey combining with the surveys in other wavebands, such as radio, infrared, X-ray and γ-ray will make important contribution to the cross-identification of multi-waveband of celestial objects.