1. http://www.niaot.ac.cn Performance and sensitivity of Low Resolution Spectrographs for LAMOST Zhu Yongtian, Hou Yonghui, Hu Zhongwen Wang Lei, Wang Jianing San Diego, 27 June, 2010

2. http://www.niaot.ac.cn Outline Brief introduction --LAMOST --LRSs Test results -- Image quality -- Throughout --Wavelength coverage and resolution Some results in early commissioning observation

3. http://www.niaot.ac.cn LAMOST

4. http://www.niaot.ac.cn Specification of LAMOST  Effective aperture: D = 4m  Focal ratio: F#= 5  field of view : 5 degrees  Number of Fibers : 4000  FRD: f/5→f/4  Fiber core diameter: 320micons or 3.3″

5. http://www.niaot.ac.cn Specification of Low Resolution Spectrograph  There are 16 LRS spectrographs 250 fibers for each spectrograph Wavelength coverage 370nm~900nm Resolution expected 1000~10000

6. http://www.niaot.ac.cn The optical layout of the LAMOST-LRS R1000/2000 R5000/10000 R1000/2000 Blue band(370~590nm) Red band (570~900nm) Yongtian Zhu, Zhongwen Hu, Qingfeng Zhang, et al. Proc. SPIE 6269(2006)

7. http://www.niaot.ac.cn Spectrograph Parameters 16 low resolution spectrographs (LRSs) for LAMOST 250 fibers(3.3 arcsecs) / Each spectrograph The fibers are separated by 578μm center to center along the 144 mm height arc slit F/4 Schmidt collimator A dichroic beam-splitter 4 VPH gratings/LRS (low, and medium dispersion respectively) 2 articulating red and blue F/1.3 Schmidt cameras field lens Corrector mirrors 4096×4136 EEV CCD 12μm square pixel size

8. http://www.niaot.ac.cn In laboratory in Xinglong Station

9. http://www.niaot.ac.cn VPH Grating sets of LAMOST-LRS

10. http://www.niaot.ac.cn VPHG

11. http://www.niaot.ac.cn VPH gratings wavefront quality

12. http://www.niaot.ac.cn Resolution powers Low-resolution mode Medium-resolution mode 3700 – 9000 Å R ~ 1000 / 2000 5100 – 5500 Å  8300 – 8900 Å R ~ 5000 / 10000

13. http://www.niaot.ac.cn 32 CCD Detectors E2V / England Chinese Company

14. http://www.niaot.ac.cn Image quality of blue band for low resolution configuration R=1000

15. http://www.niaot.ac.cn Image quality of red band for low resolution configuration (R=1000)

16. http://www.niaot.ac.cn Image quality for medium resolution configuration (R=5000)

17. http://www.niaot.ac.cn Image quality

18. http://www.niaot.ac.cn Image quality (with 1.6″slit) two dimensional spectra of arc lamp (with 1.6″slit)

19. http://www.niaot.ac.cn Throughput Throughput of LAMOST-LRS without considering the CCD quantum efficiency and fiber transmission loss

20. http://www.niaot.ac.cn Wavelength coverage and resolution CCD can cover about 348nm(red band),234nm (blue band) The wavelength range: 365-599nm (blue band) 565-913nm(red band) The resolution at central wavelength: 1100 (at 740nm), 1040 (at 480nm) The 1D spectrum of arc lamp

21. http://www.niaot.ac.cn The twilight sky spectra obtained by LAMOST Blue band Red band

22. http://www.niaot.ac.cn Some observation results during the early commissioning phase (in the winter 2009) A very bright i = 16.44 quasar in the ‘redshift desert’ discovered by LAMOST (Xue-Bing Wu1, Zhaoyu Chen1, Zhendong Jia et al.)(2010) Eight new quasars discovered by LAMOST in one extragalatic field (Xue- Bing Wu, Zhendong Jia, Zhaoyu Chen et al.) (2010) LAMOST Discovers Quasars Behind the Andromeda Galaxy(Zhi-Ying Huo, Xiao-Wei Liu, Hai-Bo Yuan et al.)(2010) Detection of New Candidates of Metal-poor Stars with LAMOST Commissioning Data (H.-N. Li, G. Zhao, N. Christlieb) (2010) LAMOST Discovers New Planetary Nebulae in the Outskirts of the Andromeda Galaxy (Hai-Bo Yuan, Xiao-Wei Liu, Zhi-Ying Huo ) (2010) ……………………………………

23. http://www.niaot.ac.cn A very bright i = 16.44 quasar in the ‘redshift desert’ discovered by LAMOST (z=2.427) Left panel: The LAMOST spectrum of SDSS J085543.40-001517.7. Right panel: The spectrum of SDSS J085543.40-001517.7 taken by the NAOC/Xinglong 2.16m telescope. The scaled SDSS composite quasar spectrum (in red color) is shown for comparison Xue-Bing Wu, Zhaoyu Chen, Zhendong Jia et al. 2010 accepted by RAA

24. http://www.niaot.ac.cn Eight new quasars 8 new quasars ( 2 quasars in the redshift desert) i magnitudes: 16.24 to 19.10 z (redshift) 0.898 to 2.773 Xue-Bing Wu, Zhendong Jia, Zhaoyu Chen et al. 2010 accepted by RAA

25. http://www.niaot.ac.cn Detection of New Candidates of Metal-poor Stars with LAMOST only the LAMOST blue arm spectra are shown, and the continuum has not been subtracted. Hai-Bo Yuan, Xiao-Wei Liu, Zhi-Ying Huo, et al. 2010 accepted by RAA

26. http://www.niaot.ac.cn Thank You ！ ytzhu@niaot.ac.cn