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Zhu, Ming (on behalf of the FAST team)National Astronomical Observatories

Chinese Academy of Sciences2012 April 2

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content

• Introduction to the FAST project

• General technical specifications

• Last Status

• FAST Science

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Unique Karst depression as the site

Active main reflectorCable - parallel robot feed support

Five hundred meter Aperture Spherical Telescope

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Guiyang

Site: the Karst region in south Guizhou Province

Site Surveying in Guizhou

Location: N25.647222º E106.85583°

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Quick Bird Fly Oct. 6, 2005

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排水隧道 1.2km

2012-03-28

FAST model construction process

1. tower

2. girder ring

3. cementdepression

4. cable & node

5. actuator

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2. General Technical Specification

Spherical reflector ： Radius ～ 300m, Aperture ～ 500m,

Opening angle 110~120°

Illuminated aperture ： Dill=300m

Focal ratio ： f/D =0.467

Sky coverage ： zenith angle 40°(up to 60°with efficiency loss)

tracking hours 0~6h

Frequency ： 70M ~ 3 GHz （ up to 8GHz in future upgradin

g ）Sensitivity (L-Band) ： A/T~2000, T~20 K

Resolution (L-Band) ： 2.9′

Multi-beam (L-Band) ： 19, beam number of future FPA >100

Slewing ： <10min

Pointing accuracy ： 8″

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Sky coverage

ZA 30 deg

ZA 40 deg

ZA 60 deg

FAST Zenith

Sky coverage

FAST vs. Arecibo

ZA 56 deg

Opening angle - sky coverage

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In layout 2000

0.327 5

HI surveying

EoR

Pulsar

VLBI

17 Lines

SETI

30.13 1.42

z~20

OH(4) H2CO(6)

Water hole

Space scienceS Band X Band

First phase Second phase

(GHz)8

70MHz

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HCOOH

CH3OH HC5N(4) CH(4) CH4

300MHz 5.2GHz

Frequency range

C Band

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Site

Active Reflector

Feed support

Measurements

Receivers

Observatory

Site

Exploration

Drainage

Earth work

Active Reflector

Disaster prevention

Main cable net

Elements

Winches

Tension monitoring

Tower

Capstan

AB-rotator & Stewart

Cables

Mark stone

Laser total station

Photogrammetry

Field bus

Optical fiber

Observatory building

Computing center

Observatory

Feed support

MeasurementsReceivers

Receivers

Backend

3.Technical plan– critical technology

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Structure of active reflector 500m girder built around hills supported by 50 pillars Backup consists of ~7000 steel strands actuated by ~2300 down tied cables driven by winches anchored into ground Errors 5.0 mm r.m.s in total

地锚背架结构 主索网

周边支承结构下拉索 索节点主索网

Feed support Three main parts of cabin suspension Cable network - adjustable system Stewart Platform - secondary adjustable system Close loop control

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Dynamic experiment on Stewart stabilizer, Sept. 2002

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Measurement – precise, quick and in long distance

Task 1: 3-D spatial positions of focus cabin Large working range up to 300 m Errors ~1 mm Sampling rate > 10 Hz

Task 2: profiles of main reflector

Number of targets ~2400 ~1000 in illuminated area Accuracy 1~2mm Sampling interval 10 sec ~ few min

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CCD ： 20Hz ； 0.5cmDGPS ： 10Hz ； 1cm

Laser Tracker ： 1KHz ；0.05mm

IMU ： 0.1

Measuring Total station

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PhotogrammetrySurveying reflector profile

1000 nodes within

illuminated area

to be scanned in real-time

period ~ 1 min

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MainControl Computer

Feed Control Computer

Reflector Control Computer

Power Monitoring

Location Reference

Time Reference

Laser Measurement

Cable Tension Measurement

Inertial Measurement

Reflector Measurement

Cable Tension Measurement

Main Control Diagram

class CORBA通知服务的结构

Notification ChannelSupplier

+ SetData()

CosNotifyComm::StructuredPushSupplier

CosNotifyComm::StructuredPushConsumer

Consumer

+ push_structured_event()

Helper

+ getChannelDomain()+ getChannelKind()+ resolveNamingService()+ resolveNotifyChannel()

CORBA Notification Service

Supplier Child

+ SetData()

Consumer Child

+ push_structured_event()User defined classes

User defined classes

federate push

push datacreate

connect

+Consumerpush data+Supplier

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Receiver layout design (2000 & 2006)

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ReceiverDiagnostics

Feed

+ polarizerLNA Mixer E/O

HI

line

Pu

lsar

VL

BI

SE

TI

mu

lti

O/E

Receiver -- Schematic Diagram

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L-band Multi-beam receivers and its prototyping

y

x

z

接收机与终端接收机与终端 - 2- 2密云模型观测情况

EMI测试

密云模型低频馈源

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No Band (GHz) Beams Pol. CryoTsys(K)

Science

1 0.07 – 0.14 1 RCP LCP

no1000

High-z HI(EoR),PSR, VLBI, Lines

2 0.14 – 0.28 1 RCP LCP

no400

High-z HI(EoR),PSR, VLBI, Lines

3 0.28 – 0.56 1 or multi RCP LCP

no150

High-z HI(EoR),PSR, VLBI, LinesSpace weather, Low frequency DSN

4 0.56 – 1.02 1 or multi RCP LCP

yes60

High-z HI(EoR),PSR, VLBI, LinesExo-planet science

5 0.320 – 0.334 1 RCP LCP

no200

HI,PSR,VLBIEarly sciences

6 0.55 – 0.64 1 RCP LCP

yes60

HI,PSR,VLBIEarly Sciences

7 1.15 – 1.72 1 L wide RCP LCP

yes25

HI,PSR,VLBI,SETI,Lines

8 1.23 – 1.53 19 Lnarrow multibeam

RCP LCP

yes25

HI and PSR survey, Transients

9 2.00 – 3.00 1 RCP/LCP

yes25

PTA, DSN, VLBI, SETI

9 sets of FAST receivers NAOC - JBO

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HI was observed using 50m model in Sept 2006.

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FAST sciences

• Neutral Hydrogen line (HI) survey

• Pulsar research

• VLBI network

• Molecular line study (including

recombination lines, masers)

• Search for Extraterrestrial Intelligence

(SETI)

FAST all-sky HI survey• Using a 19 beam L-band receiver to map 2.3π sterradians

FAST sky at 40 sec per beam, doable in 1-2 yrs.– Expect about 1 million detections (Duffy et al. 2008) with MHI< 1011

Mout to z ~ 0.15 in a range of environments including Coma, Hydra, Ursa Major, Persues-Pisces supercluster plus neighboring voids.

• Large HI database for T-F relation, peculiar velocity study of the local universe with a larger volume.

• Extend ALFALFA Sky coverage

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Duffy et al (2008)

Number of galaxies to

be detected per day

(18h) using FAST 19

beams with different

integration time

---- 6 sec

---- 60 sec

---- 600 sec

---- 6000 sec

---- 60000 sec

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Xuelei Chen Veff vs scale ¼ sky coverage survey by FAST ---- 6 s 44 days---- 12 s 88 days----1 min 440 days

Duffy et al Spectra errors

Deep mapping of Nearby Galaxies

• To map a 4 square degree area, with an integration time of 10 minute per beam, in 10 hours we can reach a 3σ sensitivity of 1.5 x1017 cm-2 per 2.1 km/s channel.

• Select regions of different environments, – void, big galaxies, clusters …

Kacprzak et al. 2010

ΛCDM COSMOLOGICAL GALAXY SIMULATIONS

How is gas accreted from the IGM onto galaxies?

• low NHI gas seen around M 31 and M 33

Braun &Thilker 2004

Prochaska et al. 2010

WALLABY: NHI~2x10^19 cm-2DINGO deep: NHI~2.6x 10^18 cm-2DINGO u-deep:NHI~1.2x10^18 cm-2

FAST

HI map of M31

Braun & Thilker 2003

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Kravtsov - Simulation on dark matter distribution in a normal galaxy

Xuelei Chen – Estimated FAST detection sensitivity of 1 min & 1 h Line width 30km/s,S/N -10

Searching for High Z HI and OH Megamaser

FAST0.1 < z < 5 0◦ < < 70◦Smin ~0.1 mJy

～ 3000 OHM

Arecibo0.1 < z < 0.45 0◦ < < 37◦Smin ~0.6 mJy

53 OHMN

2

min)1(~ zSN

The simulated uv-coverage of EVN+FAST for sources of Declination 10 and 60 degree

Search for binary SMBH

• Galaxy mergers yield inspiraling, binary, and recoiling black holes that may be detectable with high resolution VLBI search for off-nuclear and binary SMBHs

• FAST+VLBI

Summary

•FAST has very high sensitivity and large coverage of the northern sky•Good for searching for weak signals, low surface brightness structures•FAST has the potential to make great contributions to HI and pulsar studies and VLBI observations

• First light expected in 2016

Website: fast.bao.ac.cn