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LAMOST
Yongheng Zhao
(NAOC)
Very Wide Field Surveys
in the Light of Astro2010
Baltimore, 15 June 2011
●A national large scientific project
◇Started in 1997
◇Inauguration in October 2008
◇Checked and accepted by national
government in June 2009
●now in commissioning stage
●Pilot survey will begin in October 2011
Structure of LAMOST
MA mirror
4000 Fiber
Positioning
units
(4.9m)
4000F
ibers
MB mirror
16 Spectrographs
(6.1m)
32 CCDs
Characteristics of LAMOST
A horizontal meridian reflecting Schmidt telescope
with an active correcting plate
●large field of view (5 deg) + large aperture (4m)
◇Active optics on thin-mirror & segmented mirrors
●4000 optical fibers on focal surface
◇Parallel controllable fiber positioning
MB
(6.1m)
Segmented Active optics for
37 sub-mirrors of MB
（July 13,2008)
24 sub-mirrors of MA (4.9m)
Segmented and thin
mirror active optics for
24 sub-mirrors of MA
（Sept. 10, 2008)
Image quality of LAMOST
Statistics
30
EE80(arcsec)
Image Quality vs Iteration
25
25
20
20
Times 15
10
15
5
10
0
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
5
EE80(arcsec)
0
1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67
Iterations
(每次迭代约2分钟)
（Nov. 21, 2008)
Image quality: d80<1 arcsec (0.3 arsec in best)
Site seeing ~ 2 arcsec
At 3.2 degree FOV
FWHM < 2 arcsec
(Apr.25, 2009)
Image quality: 0.3-0.4 arcsec
Seeing: 1.7-2 arcsec
Telescope
◇Declination:
◇Effective aperture:
◇Field of view:
-10
60
4.9m
4.2m
5 degree
◇Seeing: 2-3 arcsec (dome + site)
90
3.6m
3 degree
Instruments
●4000 Fibers (130km)
●4000 Fiber positioning units
●16 Spectrographs
◇250 fibers per spectrograph
●32 4k x 4k CCD Cameras
◇E2V CCD chips
Fiber positioning units
8.
75
8.
单元1
Ø4
75
1
2
单元2
3
4
26
Double arm scheme
Focal plane
Positioning unit with 2 step motors
4000 fiber positioning units
S-H sensor
Guiding
CCDs
for MA
Positioning accuracy of 4000 fibers
● 96% < 0.5 arcsec (50 microns)
Coordinates
●Coordinates of 4000
fibers on focal plane
●Celestial coordinate
with CCDs
Focal plane: expansion <==> contraction (changing with temperature)
Focal length:
longer
<==>
shorter
(moving of focal plane)
Move 1-2 mm (focal length ~ 20m)
Image quality is controlled by active optics per minutes
Accuracy of fiber
positions
1 sigma < 0.6 arcsec
◇90%<1 arcsec
◇50%<0.5 arcsec
0.65
0.6
光纤偏离量（角
0.55
0.5
sigma(ra)
sigma(dec)
0.45
0.4
0.35
0.3
0.25
22-Apr
27-Apr
2-May
7-May
12-May
17-May
日期
22-May
27-May
1-Jun
6-Jun
16 spectrographs
250 fibers per spectrograph
RL = 1800 (2/3 slit width)
Spectral range:
blue: 370—590nm red: 570—900nm
Throughput
5%
from
atmosphere
to CCDs
10%
LAMOST software systems
TCS
Input
catalog
SSS
OCS
ICS
DHS
2D pipeline
1D pipeline
Data
center
Data
manage
Early Sciences
●M31 area
◇Planetary nebulae in M31
◇Kinematics + populations of M31
◇Quasars beyond M31
●Quasars selected
●Metal-poor stars selected
M31 area
M31 area
Sep.11,2010
Planetary Nebulae in M31
◇17 new PNs
◇19 confirmed
two exp. in Oct. & Dec. 2009
(Yuan et al. 2010)
Beyond M31:
(Huo et al. 2010)
14 new QSOs：z<2
Kinematics and Stellar Population
of M31 galaxy (Zou et al. 2011)
◇BATC 19 colors
◇LAMOST 2 exp.
Oct. & Dec. 2009
8 New QSOs
(Wu et al. 2010)
1 exp. In Dec. 2009
A very bright (i=16.44) quasar in
the ‘redshift desert’
UKIDSS (Y-K) + SDSS (g-z)
Candidates of metal-poor stars
(Li et al. 2010)
◇19 with S/N>15
◇9 with [Fe/H]<-1
(Wu et al. 2011)
1D Pipeline 
●8 MP stars
1: [Fe/H]~-2.7
Plan in 2011
●Oct. 2011:
◇pilot spectroscopic survey
●Improve continually
◇Fiber position
◇Efficiency of 16 spectrographs
◇Dome seeing
Limit magnitude
●S/N>10
●1800s exposure
●Seeing = 3” or 2”
●g <
18.9， 19.3
●i<
19.0， 19.4
Scientific objects of LAMOST
● Structure and evolution of the Galaxy
◇ discovery of spheroid substructure
◇ identify smooth component of spheroid
◇ constrain Galactic potential and dark matter
◇ structure of thin/thick disks, including chemical abundance and
kinematics
◇ search for extremely metal poor stars
◇ search for hypervelocity stars
◇ survey OB stars and 3D extinction in Galaxy
◇ globular cluster environments
◇ properties of open clusters
◇ complete census of young stellar objects across the Galactic plane
● Study of extra-galactic astrophysics and cosmology.
◇ Studies of large-scale structure of universe
◇ Baryon Acoustics Oscillations => Dark energy
◇ Formation and evolution of galaxies
◇ AGN physics
◇ Accurately measure luminosity functions & star-formation rate
densities with redshift & environment
◇ Detailed studies of local low-luminosity galaxies
Spectroscopic Surveys
●Stellar survey (7.5 M objects)
◇Halo structure
◇Disk star + open clusters
◇Anti-galactic center
●Extra-galactic survey (6.3 M objects)
◇Galaxy and QSO redshift survey
◇Swallow, deep, EMG, QSO
Scheme of LAMOST Operation
NAOC
LAMOST
Science Committee
LAMOST
Operation Center
WG for
Stellar survey
WG for
Extra-galactic survey
WG for
LAMSOT performance
Survey planning
+
Data processing
Observation
+
Operation
Equipment
maintenance
● LAMOST Science Committee
◇ combine 2 survey plans
◇ organize research groups
◇ Data policy (SDSS-like)
Contact to: Gang ZHAO ([email protected])
● LAMOST Operation Center
◇ Pilot survey from Oct. 2011
◇ Regular survey will begin in 2012
Contact to: Yongheng ZHAO ([email protected])
Thank You！