Two general purpose optical telescopes in China: 6.5m and 12m

Xue-Bing Wu(KIAA & DoA, Peking University)

Contributors: Luis Ho, Linhua Jiang, Xiaohui Fan, Jianmin Wang, Jinming Bai, Xiangqun Cui, Dingqiang Su, Ji Yang, Gang Zhao, Yongtian Zhu …

(KIAA-PKU; IHEP; YNAO, NAOC, NIAOT, PMO, NJU,…)

The 10th East Asian Meeting on Astronomy (Seoul, 2016/09/27)

Content

• Requests of general purpose large telescopes• A 6.5m optical/IR telescope• A 12m optical/IR telescope• Site in China• Summary

Cosmology: Need to discover a large sample of most distant objects using optical/NIR telescopes

reionization

Domestic optical telescopes & TAP• Opt. telescopes in China ：– LAMOST 4m ： spectroscopic survey on bright sources

(seeing & site limitations)– 2.4m ： largest general purpose one, too many

requests– 2.16m ： old, site problem

Telescope Access Program in China (TAP)– Many requests ； Over subscription rate ~ 3– Only two with aperture>6m ， 16nights/year in total

The problem• Current status ： 2m(China) : 10m(world) ≈ 0.2 More & more observers in China ； more & more requests of telescope time

TAP ： can not fully solve the problems

Comparison with radio: Tianma-65m,FAST-500m,SKA,…

When can we reach the world level in optical/NIR?

• In the near future ： 5-10 years

X: 30m > 0.2 X > 6m

we need a general purpose large aperture (>6m) telescope as soon as possible!

Using 2.4m can not find fainter quasarsOur new quasars Wang, Wu, Fan, et al. (2016, ApJ, 819, 24)

Follow-ups need large telescopes

2.4m + MMT (6.5m) + LBT (2*8.4m) opt. spectroscopy

Wu, Wang, Fan et al. (2015, Nature, 518, 512 )

LBT + Gemini-N(8.1m) + Magellan(6.5m)NIR spectroscopy

An ultraluminous quasar with a 12 billion solar masses BH at z=6.3

What we need

• Need a general purpose telescope with aperture >6.5m （ 2m telescopes can be used for special programs ）

• Need imaging, spectroscopy, multi-slit, multi-fibers…

• optical ＋ Near-IR

General purpose large aperture opt./IR telescopes(>6.5m) in the world

An example of 6.5m ： Magellan

Good site

Many instruments

High quality

Magellan• 6.5m x 2， Baade & Clay• Las Campanas Obs., Chile

Main Mirror Narrow Field Wide Field

Magellan: many instruments• Baade

– IMACS: Inamori Magellan Areal Camera and Spectrograph, wide-field imager and multi-object spectrograph

– MagE: Magellan Echellette, moderate-resolution(~4000) in optical– FourStar: A wide field near-infrared camera – FIRE: Folded port InfraRed Echellette, moderate resolution(~6000) in near-

infrared(0.8-2.5um)• Clay

– MIKE: Magellan Inamori Kyocera Echelle, high-throughput double echelle spectrograph

– LDSS3: Low Dispersion Survey Spectrograph, a high efficiency, wide-field multislit spectrograph

– MEGCAM: large mosaic CCD camera with a 24' x 24' field-of-view (f/5)– PFS: Planet Finding Spectrograph– M2FS: Michigan/Magellan Fiber Spectrograph (128fibers)– MMIRS: JHK imager and multislit spectrograph (f/5)– MagAO: Adaptive Optics system

Instruments of 6.5m

Imaging:IMACS/Magic (optical), MegaCam (wide field), PANIC (JHK Imager)

Spectroscopy:IMACS (low-R), MIKE/MagE (echelle, moderate-R), LDSS/MMFS (multi-slit/fiber, low/high-R), FIRE (NIR echelle), IFU…

Magellan

The 6.5m telescope in China is Magellan-like !

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A 12m Large Optical/NIR Telescope (LOT)

The Main Parameters of Telescope

Parameters Targets

Aperture of primary mirror 12m

WavelengthFor prime and Cassegrain focus: 0.35µm~1.6µm

For Nasmyth and Coude focus: visible~near-infrared

FOVPrime focus ： 1.5º; Cassegrain focus: 20′

Nasmyth focus: 10′; coude focus: 1.5′

Image qualityFor seeing limited: 0.8″

For infrared diffraction limited:0.03″(@1.6µm)

Pointing accuracy ≤ 2″(rms)

Tracking accuracy ≤ 0.1″(rms) （ 10 minutes ）17

Prime focus corrector

Move away secondary mirror

Cassegrain focus

Coude focus

Prime focus

Primary mirror ， F/1.6 (84 hexagonal with 1.44-m diagonal

diameter) segments

(SYZ relay mirror)

The Optical Layout Of LOT

Nasmyth focus

D.-q. Su, M. Liang, X. Yuan et al., 2016, MNRAS, 420, 2286

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Subaru-like

Same as TMT

Focus F number Diameter of FOV

Wavelength（ nm ）Image

quality （ 80%）

Nasmyth focus 12.8 10′ Reflective 0.001″

Coude focus 50 1.5′ Reflective 0.003″

Cassegrain focus 4.8 20′ 350 ～ 1600 0.5″

Prime Focus 2 1.5° 350 ～ 1600 0.5″

Image Quality of Optical System Design

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D.-q. Su, M. Liang, X. Yuan et al., 2016, MNRAS, 420, 2286

Primary mirror ： composed of 84 hexagonal segments

The secondary mirror and the relay mirror ： optical system collimation and focus switch

The relay mirror ： mirror shape control

Active Optics System

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Total height: ~ 31m

Mounting diameter: 22m

Nasmyth platform ： 8 * 10m

Total weight ： ~ 600 tons

Telescope Structure

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Instruments Mode FOV Wavelength(nm) Resolution Main scientific objects

Imaging spectrograph Seeing limited 20’

 350-1000

1000-5000Resolution

of imaging < 0.8’’

High quality spectrograph of galaxies for measuring the populations, chemical compositions, and dynamics.near field cosmology.

Multi-objects fiber spectroscopy Seeing limited 1.5° 370-1000 2000-20000 The evolution of universe and the

nature of dark energy

High resolution spectrograph Seeing limited 10 360-1000 50000-110000

 Chemical abundance of celestial bodies

IFU spectrograph Seeing limited 30x10 380-1000 4000 Gravitational waves, the evolution and construction of galaxies, the measurement of cosmological parameters using supernova.

Exoplanet imagerDiffraction

limited（ with AO ） 20x20 1100-2400contrast ratio （ 10 － 8~10 －

9 ） exoplanet research

Near-infrared imagerDiffraction

limited（ with AO ） 30  J,H  0.05 Gravitational waves source. Terrestrial exoplanets

Near-infrared multi-slit

spectrometerSeeing limited 5′ ~10′ 900-1600 4000 The origin and evolution of celestial

bodiesNear-infrared high

resolution spectroscopy

Diffraction limited（ with AO ）  10 J,H  100000 The atmosphere of exoplanets, and

the chemical abundance.

Scientific Instruments of 12m (preliminary)(The yellow area indicates the first Instruments)

Site in China

Rain

Ali

Alii

Observing conditions comparison of Ali, MK13N and Armazones site

Parameters Ali MK 13N Armazones

Geographic coordinates E 80°01'33"N 32°19'35"

W155°28'52"N 19°49'59"

W70°11'31"S24°35'22"

Altitude [m] 5050 4050 3064Seeing ["] 0.82 0.75 0.64

Clear cloud statistics [%] 63.7% 70.9% 82.5%

Photometric fractionsuitable for astronomy

[%]80.7% 87.2% 96.1%

Cloud: clear fraction (by Satellite) [%]

72.4% 78% 86%

Precipitable water vapor [mm]

0.97 1.9 2.9

Night wind speed [m/s] 6.0 5.7 7.2

Night humidity [%] 25 30 21

Site Survey Results at Ali

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Ali Observatory, Tibet（ 5050m above the sea）E 80°01'33"N 32°19'35"

• Ali site is 25km away from the northern Shiquanhe town which is the Ali area administrative office location, and 30 km away from the southern Khun SA airport. It is between the two East-West ridge. The logistics conditions are almost complete in the site. • There is a preliminary road network. A dual channel power line through the site.• The residents population is 12 thousands in the area. A pan for the protection of night sky is proposed.

★ N32.19 E80.01, 5050m

Ali Site

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Summary• Between the current 2m and future 30m telescopes,

we absolutely need telescopes with aperture >6m. • A 6.5m telescope and a 12m telescope concepts were

proposed in China. 12m telescope has been selected as one of the NDRC 13th Five-Year Plan projects in China

• These telescopes need to be general purpose ones, with multi-functions of imaging, spectroscopy (optical + near-IR)

• Need to be built as soon as possible (probably in Ali, Tibet), though site survey is still ongoing

• Collaborations from EA countries/regions are especially encouraged Thank you !