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China's largest optical telescope helps peer into the universe evolution


Date: Oct 23rd, 2008

Author: CAS NEWS

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   How has the universe been formed and evolved? What about the Milky Way consisting of tens of billions of stars? These questions have kept people wondering in the whole history of human civilization.

   The wide field and large sample astronomy, which focuses on extragalactic and stellar spectroscopic surveys, is expected to shed new light on these and other issues. As the optical spectrum contains abundant physical information of distant celestial objects, the spectral acquisition for a huge amount of the objects is the key to studies in the field. However, among the billions of various celestial bodies recorded by imaging survey technologies, only 1/10,000 has gone through the spectral observation.

   Now a new telescope with wide field of view recently developed by CAS astronomers will solve the bottleneck of spectral observation in astronomy. With its powerful spectroscopic survey ability, the telescope, named LAMOST (the large-area multi-target optical-fiber spectral telescope), could push the large sample spectroscopic sky survey deeper and wider, making significant contributions to the study of extra-galactic astrophysics and cosmology, such as galaxies, quasars and the large-scale structure of the universe.

   Formaly inaugurated on 16 October at the Xinglong Station under the National Astronomical Observatories at CAS (NAOC), the largest optical sky-watch facility in China will also enable the country to carve a niche in the international astronomical community in terms of types of telescopes: the largest aperture among those with a wide field of view.

   During its first test observation on 27 September,LAMOST obtained more than 1,000 spectra of objects. Then it can continuously obtain as many as 2,000 spectra of objects during a single operation. This has made it a telescope that possesses the highest spectrum acquiring rate in the world. The scientific goal of LAMOST focuses on the extragalactic observation, structure and evolution of the Galaxy, and multi-wave identification. Its spectroscopic survey of tens of millions of galaxies and others will make substantial contribution to the study of extra-galactic astrophysics and cosmology.

   This 235-million-yuan (about $33 million) project was proposed in the early 1990s by a research group headed by Profs. WANG Shouguan and SU Dingqiang from NAOC, both being CAS Members. It has won worldwide support from the astronomical community. In 1996, a formal proposal for the project made by CAS was listed, after repeated reviews, into "the National Mega-Science Facilities Program." The proposal was approved by the State authorities in April 1997. Its construction was started in September 2001. In August 2008, all its hardware components were in place, and initial test was launched.

   The advanced facility has eight subsystems: optical; active optics and support; mounting and tracking; telescope control; instruments (fibers, fiber positioning, spectroscopes, and CCDs); enclosure; observatory control and data processing; and input catalogs and survey strategy. The key innovation of the project is the concurrent adoption of the active optics techniques both for thin and segmented mirrors on its reflecting Schmidt telescope corrector, making the LAMOST a unique astronomical instrument in combining a large clear aperture and a wide field of view. The parallel controllable fiber positioning system enables it to shoot the problem of precisely locate 4,000 celestial objects simultaneously.

   Its design and construction were mainly in the charge of the Nanjing Institute for Astronomical Optics and Technology under NAOC, the NAOC headquarters and University of Science and Technology of China. As a key national facility, the telescope will open to the whole Chinese astronomical community, and will be active in carrying out international cooperation.