Progress of the Chinese SONG Nodes

Xiaojun Jiang, Fei Zhao

National Astronomical Observatories, Chinese Academy of Sciences

2010.03

• Overview of Chinese standard and

customized nodes

• A preliminary design review

• Site information

• Candidate manufacturer(s)

• Project schedule

Overview of Chinese nodesOverview of Chinese nodes

• Two nodes: Standard & Customized

• Chinese Standard SONG Node - Original SONG node + Wide Field 3-color Photometer

• Why a customized node? - General purpose photometric telescope - Monitoring of variable objects

- Ground follow-up observations

- Participating observing campaigns and SONG’s microlensing program

Why a customized node? (ctd.)

Chinese Standard Node

• Aperture ： 1m

• Alt-Az

• Classic Cassegrain

• 2 Nasmyth platforms

① Lucky imaging

② HRS + 3-color photometer

• M1 & M2 make an F/37 beam– ~f/6.1 reducer, offers15’x15’ FOV

• Pointing precision ： 5” RMS

• Pointing speed ： 20°/s Max

• Dome: Φ ≈5.5m

Standard Node - Standard Node - NasmythNasmyth platform 1platform 1

– to lucky imager• F/37 • ADC + optical derotator• Focus monitor• WL split @650nm for

vis/red cameras

Standard Node - Standard Node - NasmythNasmyth platform 2platform 2

– 3-color photometer• split by a folding mirror (M4) with central hole• F/37 – F/6.1 reducer• monitoring field stars around central target by using the 3-color photometer w/ 15’x15’ • 3-color: B 、 V 、 R• iKon-L 936: 2048*2048 (13um)• Mechanical derotator

– HRS• as per standard SONG HRS design

Standard node: 3-color photometer

• FOV :≧ 15’ x 15’

• Focal length≦ 6100mm w/ reducer

• Image quality：Encircled energy (80%)

diameter : Ф40micron (each of the BVR bands)

40micron corresponding to FOV of 1.4” @ F=6100mm

Ovserview of Chinese

Customized Node• 1m, Alt-Az mount

• M1 & M2 make a F/37 beam

• M2& M3 offer a 24’x24’ FOV

• two Nasmyth platforms

① Lucky imager (Same as the Std node)

② CCD photometer with 24’x24’ FOV

• Pointing precision ：5”RMS

• Pointing speed ： 20°/s Max

• Dome: Φ ≈5.5m

Inner surface of each port between detector and M3

stray light stops

Inner surfaces of the M2&M3 baffle ,Upside of the M1 aperture stop

knife-edged vanes

Surfaces of baffles and M1 enclosure that can be seen by the detector directly

Enhanced black paint

Stray Light control

Optical Design review Optical Design review

• Achieved diffraction limit （ λ/20RMS @633nm ） over Φ6’ FOV with classic Cassegerain design – satisfy the requirement of LI

• Difficulties:

– High-power reducers for both nodes: two

solutions

– Layout of 3-color photometer for standard

node: compromise or not?

High-power reducer: solution 1• 6 elements in 6 groups

• Max clear dia. 194mm (dense crown)

• BFD: 35mm from the rear surface (need to be optimized)

• Fits customized node after optimization

Vignetting less than 30% on the F/6.1 image

High-power reducer: solution 2 Re-image Focal ReducerRe-image Focal Reducer

Intermediate focal plane(Field stop)

Intermediate pupil image(Lyot stop)

Prism as beam splitter(Options for multi -channel photometry)

D=1010

Re-image Focal ReducerRe-image Focal Reducer--F/37 to F/6.1

D=1010

Intermediate focal plane (Field stop)

Folding mirror with central hole

Prism as beam splitter(for multi-channel photometry)

Intermediate pupil image (Lyot stop)

Re-image Focal ReducerRe-image Focal Reducer--F/37 to F/6.1

Sumarry of re-image focal reducer

9 lens in 9 groups

Front lens Φ=192mm, Dense Crown glass

Lens after that:

aperture diameters less than 110mm

Dense Crown and Dense flint glasses

BFD 146mm

80% energy within Φ40um (FOV 15’x15’) in V band

Transmittance will be decreased by ≈30%

3-color photometer’s layout is a critical issue

Summary of preliminary optical designSummary of preliminary optical design

• Optical quality of M1 + M2 meets the requirement of Lucky imaging;

• The design of F/37-to-F/6 reducers for both nodes are feasible, but need further optimization;

• Optical layout of the 3-color photometer in the standard node is a tough job, may need make compromise with astronomers – use 2-color or give up the simultaneity

Site Information in ChinaSite Information in China

2005.08.31 7

Delingha

Urumqi

YNAO

SHAO

Changchun

NAOC

PMO

Xinglong(LAMOST)Miyun HuaiRou

NIAOT

Urastai

FASTGaomeigu

Site information in China

Distribution of clear nightsDistribution of clear nightsGMS + NOAA 1996 -2003, J. Mao et al 2004

Cloud distribution at 2:00BJTCloud distribution at 2:00BJTCMA 2425 stations 1961-2008, Y. Zhang et al

High Vast LandClean Dilute AirLess cloudyCold, DryDark, Quiet

Light pollutionLight pollution

2005.04 Karasu, Xinjiang2005.04 Karasu, Xinjiang

2005.08 Oma, Tibet2005.08 Oma, Tibet

Oma: Oma: N32 32 E83 03, 5100mN32 32 E83 03, 5100m

Karasu: Karasu: N38 10 E74 48, 4500mN38 10 E74 48, 4500m

Oma 5000mOma 5000mKarasu 4500mKarasu 4500m

Site Survey carried out by NAOC

⊙⊙⊙

⊙⊙

⊙⊙

喀什

叶城

物玛阿里

措勤

卡拉苏

拉萨↙↙

airport &train station

↙↙

airport &train station

Kashi-Karasu : 190km ~ 2 hr Oma -Lhasa: 1000km ~ 2 days

airport @2010airport @2010

DIMM seeing DIMM seeing domedome

10m10m tower tower weather stationweather station

40 m CT2 tower40 m CT2 tower

2007.10 Karasu2007.10 Karasu

MIR cloud MIR cloud monitormonitorSBIG seeing SBIG seeing

monitormonitor

SBIG cloud SBIG cloud monitormonitor

Instrument setup & campaignInstrument setup & campaign

40 m CT2 tower40 m CT2 tower

DIMM seeing DIMM seeing domedome

weather station weather station 10m10m towertower

4.5 m antenna 4.5 m antenna Satellite communication Satellite communication

2008.11 Oma Site2008.11 Oma Site

SBIG seeing SBIG seeing monitormonitor

MIR cloud MIR cloud monitormonitor

Renewal Renewal power supplypower supply

CASS CASS 20092009 ：： new site for small telescopesnew site for small telescopes

Candidate ManufacturersCandidate Manufacturersin Chinain China

• Nanjing Institute of Astronomical Optics &

Technology (NIAOT)

• Nanjing Astronomical instruments Co.,Ltd

(NAIRC)

• Shanghai Astronomical Observatory (SHAO)

• Changchun Institute of Optics, Fine Mechanics

and Physics (CIOMP)

• Institute of Optics and Electronics (IOE)

• NIAOT is the unique  institute in China specialized in reserach and developing astronomical technology, professional astronomical telescopes and instruments.

• Major Projects Involved– LAMOST– FAST– SST– Antarctic Telescopes

Large sky Area Multi Objects Spectra Telescope (LAMOST)Large sky Area Multi Objects Spectra Telescope (LAMOST)

LAMOST is a quasi-meridian reflecting Schmidt telescope laid down on the ground with it’s optical axis fixed in the meridian plane. The effective aperture of LAMOST is 4m. It’s focal plane is 1.75m in diameter, corresponding to a 5 degree field of view, may accommodate as many as 4000 optical fibers. So the light from 4000 celestial objects will be led into 16 spectrographs.

LAMOST-Mb with 37 sub-mirrorsLAMOST-Mb with 37 sub-mirrors

LAMOST-Ma with 24 sub-mirrorsLAMOST-Ma with 24 sub-mirrors

16 Low/Medium16 Low/MediumResolution Resolution

Spectrographs Spectrographs RL = 1000/2000

RM= 5000/10000

4kx4k CCD, 12μ/pixelVPHG (Wasach optics )

Spectral range:

Low blue: 370—590nm

red: 570—900nm

Medium blue: 510nm — 540nm

red: 830nm — 890nm

First of 16 LRS

Space Solar Telescope (SST)Space Solar Telescope (SST)

Main charactersMain characters::0.1" 0.1" 0.15" space resolution for vector 0.15" space resolution for vector magnetic field and velocity field etc.magnetic field and velocity field etc.2D spectrograph2D spectrographmagnetic analyzer with accuracy ~ 10-4 magnetic analyzer with accuracy ~ 10-4 0.5" soft X-ray images at 4 bands 0.5" soft X-ray images at 4 bands simultaneouslysimultaneously

Optical design:Optical design: Diameter: 1 M; Diameter: 1 M; Focal rate : 3.5 to 1, Focal rate : 3.5 to 1, FoV : 2.8 ' x 1.5 ', FoV : 2.8 ' x 1.5 ', Diffraction limit: Diffraction limit: 0.1"0.1"—— 0.15 0.15““

1 ） tube material ： INVAR-362) Tube sealed and filled with dry nitrogen3) Tilted window with ITO (snow-removing and deicing)4) Special damping structure for safe transportation

SONG-CHINA project schedule

• May 2010: finish preliminary design of both nodes

• December 2010: past design review ,place order of the

telescopes/instruments

• December 2011: finish site-testing

• April 2012: start construction of enclosures/control rooms

• December 2012 ： finish on-site installation and past

acceptance tests, engineering runs

• April 2013: science operations

Thank You !Thank You !