Thierry FuscoGérard Rousset

NAOS-CONICA (a.k.a NACO) for the VLT

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NACO History

~5 years

CFT for the VLT Coude AO feasibility study: Feb. 91CONICA contract signed with MPIA et al: 1991VLT Coude AO feasibility study: Matra-Marconi-Space in 92-93VLT Coude AO project (4 AO systems) cancelled: Council Dec 93NAOS concept is proposed by ESO to STC-FC-Council: end 1994CONICA is redesigned by MPIA et al.: end 1994NAOS Preliminary Inquiry & CFT: Dec. 94- March 96NAOS audit: March 96- December 96NAOS contract signed with ONERA et al.: March 97CONICA FDR: mid 98NAOS PDR - FDR: Oct. 98 - June 99NAOS-CONICA PAE: Sept. 2001NAOS-CONICA first light: Nov. 2001NACO open to the community: Oct 2002

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NAOS in figures

4 Institutes : ONERA, LAOG, ODP, ESO

5-year project ~5 Meuros 60 FTEs Tests in France in 2001 First light 25/11/2001

NAOS: 2.3 tons

CONICA: 0.9 tons

(attached to Nasmyth rotator)

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Two Shack-Hartmann Wavefront Sensors,each including 2 pupil samplings: 14x14 (144 valid subap.) and 7x7 (36)

NAOS main features (1/2)…

IR WFS :• Spectral range: 0.8 - 2.5 mm• 14x14 array + 2 arrays of 7x7 on 3 fixed detector areas (0.8 and 0.4 arcsec/pix)• Rockwell Hawaii 1024x1024 pixels frame rate from 180 to 15 Hz noise : from 10 to 20 e- • 36 configurations !!!

VWFS : • Spectral range: 0.45 - 1 mm • 2 interchangeable lenslet arrays (0.29 and 0.58 arcsec/pixel)• EEV CCD 128x128 pixels, 16 outputs (ESO) frame rate from 444 to 15 Hz binning, windowing noise : 2.9e- to 5.4e-• 48 configurations!!!

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NAOS main features (2/2)

Dichroic Wheel:• 2 neutral and 3 dichroic BS

WFS Field Selector: • NGS in 2 arcmin FOV• Tracking (refraction, flexures, moving object)

Deformable mirror (Cilas)• 185 actuators (piezo-stacked), 10 m stroke

2-axis Tip/Tilt Mirror: 2.1 mas resolution

Real time Computer (Shakti):• 0dB Error BW: 27 Hz (V) and 22 Hz (IR)• modal optimization (every 2 mn)• on-line performance and seeing

Off-line preparation software

Observation software: • NAOS configuration, control of Field Selector• Aberration pre-compensation, chopping

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Diameter: 2m Max Length: 3m Thickness: 0.7m

IR WFS

V-WFS

DM Output

input

Mechanical structure PM 2

PM 1

TTM

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Pupil sampling

185 useful actuators

144 useful subapertures

Telescope pupil

Central obscuration

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CONICA

1-5 microns (1Kx1K) 34 filters 4 grisms 7 cameras 3 slits Polarimetry Coronography Fabry-Perot Imaging

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Flange to “rotate” CONICA

Imaging: 1-5 µmPolarisationCoronographySpectro 1-5 µm: max 2500Fabry Perot: R=1800

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VLT Nasmyth Platform

NAOS

CONICA

VLT-UT4: F/15Cable twist

… and NAOS-CONICA became NACO …

They lived happy everafter … and they had plenty of photons …

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• High order correction in near IR (Sr(K)=70%)• Faint limiting magnitude star in V (Mv>17)• IR wavefront sensing for embedded objects• Compatibility with LGS operation• Minimization of instrument thermal and sky bkg effects

• Minimise the number of optical surfacesno derotator direct rotation of NACO

• AO with Chopping and Counter chopping• Very low flexure requirements (NAOS & CONICA)• “background limiter” to reduce dichroic background

• High image quality for CONICA (Sr(K)>90%)• Low Instrumental background <1e• One detector for 1-5 m!• Many CONICA observing modes: Imaging, coronagraphy, Low resolution spectroscopy, FP, polarimetry

And now … let’s go on sky … with a pit-stop in lab

NACO challenges

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12Result: SR 65 % @ 0.93 arcsec seeing (specification 70 %)

First laboratory results Turbulent image AO corrected image Image without

turbulence

SR = 69% 90%Seeing 0.6 arcsec

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Paranal re-integration NOOOOOOOO !Oh my god …

I have to make it work ! YESSSSSSSS !

I’m gonna observe in J, H, K, L, M …

I’m gonna detect exoplanets

The astronomer The instrumentalist

(use to be an astronomer )

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Let’s go on the telescope

Is this going to work??

Well … maybe ...

Of course it will !!!!!!!!!!

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High Strehl (K)50%

And yes … it worked and it is still working

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Faint star correctionStrehl (K)=17%

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The Galactic Centre with and without AO in L'-band seen by NAOS(Clénet et al. 2004)

The Galactic CentreThe Galactic Centre

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Thetis

Differential tracking

Composite image H-K20.6 arcsec diameterresolution 70 mas or 410 km~10 sec exposure time

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Io with NAOS-CONICALong wavelengths

capabilitiesBr-L’

230/4.2 s exposure68mas or 210 km

1.2 arcsec diameter

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On-sky SR behavior versus magnitude

Visible WFS IR WFS

• Bright NGS : SR loss of 20-30 %• Faint NGS : significant correction

Stars: seeing 0.7 ’ ’, crosses: 1.1 ’ ’, diamonds: 1.1 ’ ’ ; 14x14 arrays: large symbols, 7x7 arrays: small symbols

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Exoplanet detection with NACO

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SR loss sources (1/2)Vibrations detected on WFS data:

On-sky

Laboratory

No vibration Vibration lines

• 16 - 18 Hz : 3000 -10000 nm²• 48 - 55 Hz : 2000 - 5000 nm²• 68 - 70 Hz : 500 - 1000 nm²

No vibration on Comas

Variations in amplitude and

occurence

No vibration in laboratoryNothing on internal source: telescope vibrations

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SR loss sources (2/2)

Telescope vibrations:

Strehl loss estimated to 10 %

Main influence on Tip-Tilt modes but other excitations detected on high order modes

Vibrations not compensated for: out of the NAOS temporal bandwidth

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Differential aberrations in CONICA and dichroics

Without turbulence, SR ~ 93 % in K with pre-compensation

With

pre-com

pen

sation b

y NA

OS

d

eformab

le mirror

No

com

pen

sati

on

At 2.15 m

At 1.09 m

SR = 93 %SR = 89 %

SR= 56% SR =66%

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Conclusion

In median seeing conditions: SR ~ 50% at K band; best Sr(K)=64% on sky

Substantial compensation with very faint NGS: Mv=17.6, SR=6% (gain of 7)

Fully automated operation (VLT software) Many features available in NAOS for specific astronomical

observations: IR WFS differential refraction, pointing model tracking on moving object, chopping, counter-chopping

241 scientific papers so far

=> 34.5 papers per year => Good scientific return !