Early Sciences &Early Sciences &Test observations Test observations

with LAMOSTwith LAMOST

Yongheng ZhaoYongheng Zhao

National Astronomical Observatories of ChinaNational Astronomical Observatories of China

• Effective aperture Effective aperture 3.6-4.9 meter3.6-4.9 meter• FOVFOV 55 （（ 1.75m linear1.75m linear ））• Number of fibers Number of fibers 40004000• Observing sky area Observing sky area -10-10 +90 +90 • Spectral resolution Spectral resolution R=1000/2000 (+5000/10000)R=1000/2000 (+5000/10000)• Survey capability spectral resolution 1nm,Survey capability spectral resolution 1nm,

integration time 1.5 hours,integration time 1.5 hours,

magnitude limit: 20.5magnitude limit: 20.5mm

• Size of fiber Size of fiber 3.30 arcsec3.30 arcsec （ （ 320 macro linear320 macro linear ））• Site seeing: ~2 arcsecSite seeing: ~2 arcsec

Characteristics of LAMOSTCharacteristics of LAMOST

Oct 20, 2007

Structure of LAMOSTStructure of LAMOST

MB mirror

Fiber Positioning

Fibers

MA mirror

Spectrographs

CCDs

Optical SystemOptical System

MBMB

(( ~ ~ 6.1m)6.1m)

Segmented Active optics Segmented Active optics for 37 sub-mirrors of MBfor 37 sub-mirrors of MB

（（ July 13,2008)July 13,2008)

24 sub-mirrors of MA 24 sub-mirrors of MA （（ ~ ~ 4.9m4.9m ））

Segmented and thin Segmented and thin mirror active optics for mirror active optics for 24 sub-mirrors of MA24 sub-mirrors of MA

（（ Sept. 10, 2008)Sept. 10, 2008)

Statistics

0

5

10

15

20

25

30

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1

EE80(arcsec)

Times

I mage Qual i ty vs I terat i on

0

5

10

15

20

25

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67I terat i ons

( 2 )每次迭代约 分钟

EE80

(arc

sec)

Image quality of LAMOSTImage quality of LAMOST

（（ Nov. 21, 2008)Nov. 21, 2008)<1”<1”

Target: < 2”Target: < 2”

At 5.2 degrees FOVAt 5.2 degrees FOV

Oct. 11, 2008

At 3.2 degree FOVAt 3.2 degree FOV

FWHM<10pixel, FWHM<10pixel, ~2 arcsec~2 arcsec

Apr.25, 2009Apr.25, 2009

Image quality: 0.3-0.4 arcsecSeeing: 1.7-2 arcsec

PointingPointing< 5”< 5”

Target: < 10”Target: < 10”

TrackingTracking

0.632“ （ 80% ）0.52" （ rms ）

Target: < 1”Target: < 1”

InstrumentsInstruments

4000 Fibers (130km)4000 Fibers (130km) 4000 Fiber positioning units4000 Fiber positioning units 16 Spectrographs 16 Spectrographs

250 fibers per spectrograph250 fibers per spectrograph

32 4k x 4k CCD Cameras32 4k x 4k CCD Cameras E2V CCD chipsE2V CCD chips

Positioning unit with 2 step motors

Double arm scheme

Focal Plate for holding 4000 fibers

8.75

8.75

Ø41 2

34

单元1 单元2

26

4000 fiber positioning units4000 fiber positioning units

Repeat accuracy of 4000 unitsRepeat accuracy of 4000 units

<0.14”<0.14”

target: <0.5”target: <0.5”

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

16 spectrographs16 spectrographs

16 spectrographs16 spectrographs

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

Efficiency of spectrograph Efficiency of spectrograph 370~900nm370~900nm

43% (peak)43% (peak)

Target Target ：： 35%35% （（ peakpeak ））

Test ObservationsTest Observations

Sept. 2008 – June 2009Sept. 2008 – June 2009 Test observations for checkTest observations for check

Several dark nights in each monthSeveral dark nights in each month

Spectra of bright starsSpectra of bright stars （（ 28/9/20028/9/20088 ））

Blue Red

Apr.1, 2009Apr.1, 2009

GalaxiesGalaxies

(g>19)(g>19)

Apr.1, 2009Apr.1, 2009

QSOsQSOs

(g>19)(g>19)

Apr. 26, 2009Apr. 26, 2009

Stars (V<19)Stars (V<19)

More than 3600 spectra got in one test More than 3600 spectra got in one test observation (>90% of selected objects)observation (>90% of selected objects)

No.4: red

No.5: red

Early SciencesEarly Sciences

Test observations for scientific WGsTest observations for scientific WGs Observations: 97 exposures (each 1.5h)Observations: 97 exposures (each 1.5h)

Oct. 2009: 20 for starsOct. 2009: 20 for stars Nov. 2009: 20 for stars, 6 for galaxiesNov. 2009: 20 for stars, 6 for galaxies Dec. 2009: 18 for stars, 10 for galaxies Dec. 2009: 18 for stars, 10 for galaxies Jan. 2010: 18Jan. 2010: 18 Feb. 2010: 7Feb. 2010: 7

Oct. 26,Oct. 26,

20092009

M31 areaM31 area

M31M31 17 new PNs17 new PNs 19 confirmed19 confirmed

two exp. in Oct. & Dec.two exp. in Oct. & Dec.

Beyond M31:Beyond M31:14 new QSOsnew QSOs ：： z<2z<2

8 New QSOs8 New QSOs1 exp. In Dec.

Candidates of metal-poor starsCandidates of metal-poor stars 19 with S/N>1519 with S/N>15 9 with [Fe/H]<-19 with [Fe/H]<-1

Pipeline Pipeline 8 MP stars8 MP stars

1: [Fe/H]~-2.71: [Fe/H]~-2.7

Candidates of metal-poor starsCandidates of metal-poor stars

ImprovementImprovement

Mar.-JulyMar.-July Positioning accuracy for 4000 fibersPositioning accuracy for 4000 fibers

Jul.-Sep.Jul.-Sep. Fine adjusting of spectrographs & CCDsFine adjusting of spectrographs & CCDs 2D pipeline2D pipeline

Positioning accuracy for 4000 fibersPositioning accuracy for 4000 fibers

2” 2” 1” 1”

M31 areaM31 area

Sep.11,Sep.11,

20102010

PlanPlan

Oct.-Dec.Oct.-Dec. Scientific test observationsScientific test observations

Jan.-JuneJan.-June Test for scientific surveysTest for scientific surveys

Thank YouThank You ！！

Positioning errorsPositioning errors

““fiber scan”fiber scan”

July 6July 6 σxσx==1.7”1.7”, , σyσy==2.3”2.3”

ΔX (“)

ΔY

(“)

Positioning of 4000 fibersPositioning of 4000 fibers

Transformation of Coords. Transformation of Coords. 4000 coordinates for 4000 fibers4000 coordinates for 4000 fibers Fiber coords. Fiber coords. Focal plane coords Focal plane coords

• 40004000 （（ xx00 ，， yy00 ，， θθ00 ）） FP coords. FP coords. CCD coords. CCD coords. （（ celetialceletial ））

• Shift, rotation, expandingShift, rotation, expanding

Symmetric errorsSymmetric errors measurement measurement correction correction

CCD3

CCD0CCD2

CCD1

Coord. of 4000 fibersCoord. of 4000 fibers

Coord. of 4 guiding CCDsCoord. of 4 guiding CCDs

Celestial coords measured by 4 guiding CCDsCelestial coords measured by 4 guiding CCDs

CCD coordsCCD coords

Fiber coordsFiber coords

July 6July 6 σxσx==1.7”1.7”, , σyσy==2.3” 2.3” σxσx==1.1”1.1” ，， σyσy==1.2”1.2”

Dome SeeingDome Seeing

日期：日期： 2009112220091122 天区：天区： 06faint06faint 中央星：中央星： 124.7456700 56.2547100 7.00 3.70 -8.40124.7456700 56.2547100 7.00 3.70 -8.40 SeeingSeeing ：： 11*0.24= 11*0.24= 2.642.64 角秒角秒（（ CCDCCD ：： 40334033 ）（时间：）（时间：

04:30)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)

光纤偏离和视宁度对极限星等的光纤偏离和视宁度对极限星等的影响影响

光纤偏离光纤偏离------------------------

视宁度视宁度

0”0” 1”1” 2”2” 3”3” 4”4” 5”5”

1”1” 0.0m0.0m 0.1m0.1m 2.0m2.0m 8.0m8.0m

2”2” 0.2m0.2m 0.4m0.4m 1.6m1.6m 3.7m3.7m 7.0m7.0m

3”3” 0.6m0.6m 0.8m0.8m 1.6m1.6m 2.7m2.7m 4.3m4.3m 6.7m6.7m

4”4” 1.0m1.0m 1.1m1.1m 1.8m1.8m 2.5m2.5m 3.5m3.5m 4.8m4.8m

5”5” 1.4m1.4m 1.5m1.5m 2.0m2.0m 2.4m2.4m 3.2m3.2m 4.1m4.1m

圆顶杂散光测量圆顶杂散光测量33 月月 99 日日 33 月月 1010 日日

光谱光谱仪仪

IscIsc Isc+IsIsc+Iskk

Isc/IsIsc/Iskk

IscIsc Isc+IsIsc+Iskk

Isc/IsIsc/Iskk

1010 147147 911911 19%19% 113113 887887 14 %14 %

1111 168168 809809 26%26% 133133 705705 23 %23 %

1212 153153 827827 22%22% 121121 720720 20 %20 %

1313 156156 798798 24%24% 129129 705705 22 %22 %

1414 143143 900900 18%18% 114114 784784 17 %17 %

1515 9494 570570 19%19% 7878 581581 15 %15 %

1616 9292 757757 13%13% 127127 795795 19 %19 %

光纤对准测定光纤对准测定单高斯单高斯拟合：拟合：

xx00 ，， yy00

FWHMFWHM

FF**, Fb, Fb

焦平面调整（焦平面调整（ 33 月）月）

光轴光轴 ++ 焦平面焦平面 共面共面

S-HS-H 中心（焦点）中心（焦点） 40004000 光纤端面光纤端面 44 导星导星 CCDCCD 靶面靶面