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The Observations of LAMOST. Jianrong Shi NAOC. 1/7 2014. The Observation of LAMOST. Jianrong Shi (NAOC). Overview. The structure of LAMOST The observation preparation How to select the plate The results from one year Pilot and two year standard surveys. Structure of LAMOST. - PowerPoint PPT Presentation
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The Observations of LAMOST
Jianrong Shi
NAOC
1/7 2014
The Observation of LAMOST
Jianrong Shi(NAOC)
OverviewThe structure of LAMOST
The observation preparation
How to select the plate
The results from one year Pilot and two year standard surveys
Structure of LAMOST
MB mirror
6.67 m×6.05m
4000 Fiber Positioning 4000
Fibers
MA mirror
5.72m×4.4m
16 Spectrographs32 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
The observation preparationFocus the MB ( Shack-Hartman MA) ~5mintues
Focus the MA and four guiding stars (center star V < 8 mag. ) ~25mintues
Moving the fibers to the accurate positions (9mintues)(Which can be done during the focus)
MB 6.67m×6.05m Focal length 20m 37sub-mirrors
8
Segmented Active optics for 37 sub-mirrors of MB
MA 5.72 m×4.4m (24 sub-mirrors)
10
Segmented and thin mirror active optics for 24 sub-mirrors of MA
11
4000 fiber positioning units (1.75m)GuidingCCDs
S-H sensorfor MA
4000 fiber positioning units
The site conditions
The statistics of the number of hours of BATC observations per night from 2004-01-01 to 2007-09-30. The dashed line shows the theoretical available time.
Sky brightness
The sky brightness in V band obtained from BATC Polaris monitor data, as a function of time from 1995 to 2011.
Telescope
Seeing: 3-5 arcsec (dome + site)Site seeing: < 2 arcsec ; Fiber size: 3.3 arcsechas a field of view as large as 20 square degrees, the effective aperture varies from 3.6 to 4.9 meters in diameter (depending on the pointing). Enables it to take 4000 spectra in a single exposure at resolution R = 1800.
Declination -10o 60o 90o
Effective aperture 4.9m 4.2m 3.6m
Field of view 5 degree 3 degree
Seeing
Comparing the seeing from guide star and DIMM during Pilot Survey (Oct. 24, 2011- Match 30, 2012 )
Throughpot (Oct. 1 2011)
Signal to Noise Ratio
Signal to Noise Ratio
Signal to Noise Ratio
Signal to Noise Ratio
Signal to Noise Ratio
Throughpot (Oct. 1 2011)
Throughpot (Oct. 2 2011)
How to select the PlateObservational conditions: (240m)weather, Moon phase, left time and seeing etc. VB(9.0<r<14.0) 3*10mB (14.0<r<16.3) 3*20m – 3*25mM(16.3<r<17.8) 3*30mF(17.8<r<18.5) 3*30mreadout ~ 8m Wish to observe two B plates and more VB plates
the image
The results from pilot surveySpectra with S/N>10( g or i band) spectra plate success ratiopilot: 597,032 397 45.6%First year: 1,191,414 768 57.9%Second year:1,207,119 697 64%success ratio: the ratio of the Spectra with S/N>10
to all the selected targetsObserved time: 914h, 1278h and 1356h
The reason for the less plates during the second year
Increase the time for foucs MB、 B plate from 20 -25 minutes, added one lamp observation and more M plates observed LSS-GAC DR1 B: 76 M: 30 F: 4 DR2 B: 75 M: 44The instrumental fail rate (The ratio of the lost time due to the instrumental problem to the observation time)Pilot: 12.5% first: 5.3% second: 4.4%
Thank You!