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Early Sciences & Test observations with LAMOST

Early Sciences & Test observations with LAMOST

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Early Sciences & Test observations with LAMOST

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  1. Early Sciences &Test observations with LAMOST Yongheng Zhao National Astronomical Observatories of China

  2. Characteristics of LAMOST • Effective aperture 3.6-4.9 meter • FOV 5(1.75m linear) • Number of fibers 4000 • Observing sky area -10   +90 • Spectral resolution R=1000/2000 (+5000/10000) • Survey capability spectral resolution 1nm, integration time 1.5 hours, magnitude limit: 20.5m • Size of fiber 3.30 arcsec( 320 macro linear) • Site seeing: ~2 arcsec

  3. Oct 20, 2007

  4. Structure of LAMOST MA mirror Fiber Positioning Fibers MB mirror Spectrographs CCDs

  5. Optical System

  6. MB(~ 6.1m)

  7. (July 13,2008) • Segmented Active optics for 37 sub-mirrors of MB

  8. 24 sub-mirrors of MA (~ 4.9m)

  9. (Sept. 10, 2008) • Segmented and thin mirror active optics for 24 sub-mirrors of MA

  10. Image quality of LAMOST <1” Target: < 2” (Nov. 21, 2008)

  11. At 5.2 degrees FOV Oct. 11, 2008

  12. At 3.2 degree FOV • FWHM<10pixel, ~2 arcsec Apr.25, 2009 Image quality: 0.3-0.4 arcsec Seeing: 1.7-2 arcsec

  13. Pointing< 5” Target: < 10”

  14. Tracking 0.632“(80%) 0.52"(rms) Target: < 1”

  15. Instruments • 4000 Fibers (130km) • 4000 Fiber positioning units • 16 Spectrographs • 250 fibers per spectrograph • 32 4k x 4k CCD Cameras • E2V CCD chips

  16. Focal Plate for holding 4000 fibers Positioning unit with 2 step motors Double arm scheme

  17. 4000 fiber positioning units

  18. Repeat accuracy of 4000 units <0.14” target: <0.5”

  19. 16 spectrographs 250 fibers per spectrograph RL = 1000/2000 RM= 5000/10000 Spectral range: Low blue: 370—590nm red: 570—900nm Medium blue: 510nm — 540nm red: 830nm — 890nm

  20. 16 spectrographs

  21. Relative efficiency of fiber to fiber (No.6 spectrograph-blue)

  22. Efficiency of spectrograph 370~900nm • 43% (peak) • Target :35%(peak)

  23. Test Observations • Sept. 2008 – June 2009 • Test observations for check • Several dark nights in each month

  24. Spectra of bright stars(28/9/2008) Blue Red

  25. Apr.1, 2009 Galaxies (g>19)

  26. Apr.1, 2009 QSOs (g>19)

  27. Apr. 26, 2009 • Stars (V<19) • More than 3600 spectra got in one test observation (>90% of selected objects)

  28. No.5: red No.4: red

  29. Early Sciences Test observations for scientific WGs • Observations: 97 exposures (each 1.5h) • Oct. 2009: 20 for stars • Nov. 2009: 20 for stars, 6 for galaxies • Dec. 2009: 18 for stars, 10 for galaxies • Jan. 2010: 18 • Feb. 2010: 7

  30. Oct. 26, 2009 M31 area

  31. M31 • 17 new PNs • 19 confirmed two exp. in Oct. & Dec.

  32. Beyond M31: 14 new QSOs:z<2

  33. 8 New QSOs 1 exp. In Dec.

  34. Candidates of metal-poor stars • 19 with S/N>15 • 9 with [Fe/H]<-1

  35. Candidates of metal-poor stars • Pipeline  • 8 MP stars 1: [Fe/H]~-2.7

  36. Improvement • Mar.-July • Positioning accuracy for 4000 fibers • Jul.-Sep. • Fine adjusting of spectrographs & CCDs • 2D pipeline

  37. Positioning accuracy for 4000 fibers 2”  1”

  38. M31 area Sep.11, 2010

  39. Plan • Oct.-Dec. • Scientific test observations • Jan.-June • Test for scientific surveys

  40. Thank You!

  41. Positioning errors • “fiber scan”

  42. July 6 • σx=1.7”, σy=2.3” ΔY (“) ΔX (“)

  43. Positioning of 4000 fibers • Transformation of Coords. • 4000 coordinates for 4000 fibers • Fiber coords.  Focal plane coords • 4000(x0,y0,θ0) • FP coords.  CCD coords.(celetial) • Shift, rotation, expanding • Symmetric errors • measurement  correction

  44. CCD0 CCD3 CCD2 CCD1 Coord. of 4000 fibers Coord. of 4 guiding CCDs

  45. Celestial coords measured by 4 guiding CCDs CCD coords Fiber coords

  46. July 6 • σx=1.7”, σy=2.3”  • σx=1.1”,σy=1.2”

  47. Dome Seeing • 日期:20091122 • 天区:06faint • 中央星:124.7456700 56.2547100 7.00 3.70 -8.40 • Seeing:11*0.24= 2.64角秒(CCD:4033)(时间:04:30) • 日期:20091221 • 天区:sky5f • 中央星:91.0300674 23.2636089 5.09 0.00 0.00 • Seeing:8*0.24= 1.92角秒(CCD:6033)(时间:1:12)