LAMOST

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The LAMOST telescope
Comparison of nominal sizes of primary mirrors of the LAMOST and some notable optical telescopes (click for detail)

The Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST), also known as the Guo Shoujing Telescope after the 13th-century Chinese astronomer, is a meridian reflecting Schmidt telescope, located in Xinglong Station, Hebei Province, China. Undertaken by the Chinese Academy of Science, the telescope is planned to conduct a 5-year spectroscopic survey of 10 million Milky Way stars, as well as millions of galaxies. The project’s budget is RMB 235 million yuan.

Optics[edit]

The optics of LAMOST comprise two roughly rectangular mirrors, each made up of a number of 1.1-metre hexagonal deformable segments, providing a focal plane 1.75 metres in diameter corresponding to a five-degree field of view. This focal plane is tiled with fibre-positioning units, attached to 4000 fibres which transfer light to sixteen spectrographs below. The larger spherical mirror MB (37 segments, fitting in a 6.67m x 6.09m rectangle) is located at an angle in a large slanted tunnel attached to a tower; the smaller corrector mirror MA (24 segments, fitting in a 5.72m x 4.4m rectangle) is in a dome at ground level.[1] Looking at the image opposite, MB is at the top of the left-hand supporting column of the tower, MA is in the left of the two domes at the right of the image (the rightmost, grey dome is an unrelated telescope), and the spectrographs are inside the right-hand column of the tower.

Each spectrograph has two 4k x 4k CCD cameras, using e2v CCD chips, with 'blue' (370-590 nm) and 'red' (570-900 nm) sides; the telescope can also be used in a higher spectral resolution mode where the range is 510-540 and 830-890 nm.[1]

Using active optics technique to control its reflecting corrector makes it a unique astronomical instrument in combining large aperture with wide field of view. The available large focal plane may accommodate up to thousands of fibers, by which the collected light of distant and faint celestial objects down to 20.5 magnitude is fed into the spectrographs, promising a very high spectrum acquiring rate of ten-thousands of spectra per night.

Scientific goals[edit]

The telescope is to conduct a wide-field survey, called the "LAMOST Experiment for Galactic Understanding and Evolution," or LEGUE. Particular scientific goals of the LAMOST include:

  • An extra-galactic spectroscopic survey to shed light on the large scale structure of the universe
  • A stellar spectroscopic survey, including a search for metal-poor stars in the galactic halo, to provide information on the structure of our Galaxy
  • Cross-identification of multi-waveband surveys

It is also hoped that the vast volume of data produced will lead to additional serendipitous discoveries. Early commissioning observations have been able to confirm spectroscopically a new method of identifying quasars based on their infrared color.[2] An overarching goal of the telescope is to bring Chinese astronomy into the 21st century, taking a leading role in wide-field spectroscopy and in the fields of large-scale and large-sample astronomy and astrophysics.

Early results[edit]

A 2011 conference presentation [3] suggests that there was initially a problem with accuracy of the fibre positioners causing poor throughput, but that this was rectified by adding an additional calibration stage.

References[edit]

  1. ^ a b Yongheng ZHAO. "LAMOST Spectroscopic Survey". 
  2. ^ Xue-Bing Wu; Zhendong Jia; Zhaoyu Chen; Wenwen Zuo; Yongheng Zhao; Ali Luo; Zhongrui Bai; Jianjun Chen et al. (2010). "Eight new quasars discovered by LAMOST in one extragalactic field". arXiv:1006.0143 [astro-ph.CO].
  3. ^ Martin Smith. "Progress and plans for Chinese surveys". 

External links[edit]

Coordinates: 40°23′39″N 117°34′30″E / 40.39417°N 117.57500°E / 40.39417; 117.57500