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

NAOS-CONICA (a.k.a NACO) for the VLT. Thierry Fusco Gérard Rousset. NACO History. CFT for the VLT Coude AO feasibility study: Feb. 91 CONICA contract signed with MPIA et al: 1991 VLT Coude AO feasibility study: Matra-Marconi-Space in 92-93

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

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  1. NAOS-CONICA (a.k.a NACO) for the VLT Thierry Fusco Gérard Rousset

  2. NACO History CFT for the VLT Coude AO feasibility study: Feb. 91 CONICA contract signed with MPIA et al: 1991 VLT Coude AO feasibility study: Matra-Marconi-Space in 92-93 VLT Coude AO project (4 AO systems) cancelled: Council Dec 93 NAOS concept is proposed by ESO to STC-FC-Council:  end 1994 CONICA is redesigned by MPIA et al.:  end 1994 NAOS Preliminary Inquiry & CFT: Dec. 94- March 96 NAOS audit: March 96- December 96 NAOS contract signed with ONERA et al.: March 97 CONICA FDR: mid 98 NAOS PDR - FDR: Oct. 98 - June 99 NAOS-CONICA PAE: Sept. 2001 NAOS-CONICA first light: Nov. 2001 NACO open to the community: Oct 2002 ~5 years

  3. NAOSin 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)

  4. NAOS main features (1/2)… Two Shack-Hartmann Wavefront Sensors, each including 2 pupil samplings: 14x14 (144 valid subap.) and 7x7 (36) • 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!!! • 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 !!!

  5. NAOS main features (2/2) • 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 • Dichroic Wheel: • 2 neutral and 3 dichroic BS • WFS Field Selector: • NGS in 2 arcmin FOV • Tracking (refraction, flexures, moving object) • Observation software: • NAOS configuration, control of Field Selector • Aberration pre-compensation, chopping Off-line preparation software

  6. Diameter: 2m Max Length: 3m Thickness: 0.7m Mechanical structure PM 2 V-WFS IR WFS TTM DM Output input PM 1

  7. Pupil sampling 185 useful actuators Telescope pupil 144 useful subapertures Central obscuration

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

  9. Flange to “rotate” CONICA Imaging: 1-5 µm Polarisation Coronography Spectro 1-5 µm: max 2500 Fabry Perot: R=1800

  10. … and NAOS-CONICA became NACO … They lived happy everafter … and they had plenty of photons … NAOS CONICA Cable twist VLT-UT4: F/15 VLT Nasmyth Platform

  11. NACO challenges • 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 surfaces • no 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 

  12. First laboratory results Turbulent image AO corrected image Image without turbulence Seeing 0.6 arcsec 90% SR = 69% Result: SR 65 % @ 0.93 arcsec seeing (specification 70 %)

  13. 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 instrumentalist (use to be an astronomer ) The astronomer

  14. Let’s go on the telescope Is this going to work?? Well … maybe ... Of course it will !!!!!!!!!!

  15. High Strehl (K) 50% And yes … it worked and it is still working

  16. Faint star correction Strehl (K)=17%

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

  18. Thetis Composite image H-K 20.6 arcsec diameter resolution 70 mas or 410 km ~10 sec exposure time Differential tracking

  19. Io with NAOS-CONICA Long wavelengths capabilities Brg-L’ 230/4.2 s exposure 68mas or 210 km 1.2 arcsec diameter

  20. On-sky SR behavior versus magnitude Visible WFS IR WFS Stars: seeing £ 0.7 ’ ’, crosses: £ 1.1 ’ ’, diamonds: > 1.1 ’ ’ ; 14x14 arrays: large symbols, 7x7 arrays: small symbols • Bright NGS : SR loss of 20-30 % • Faint NGS : significant correction

  21. Exoplanet detection with NACO

  22. On-sky No vibration Laboratory SR loss sources (1/2) Vibrations detected on WFS data: • 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 Vibration lines No vibration in laboratory Nothing on internal source: telescope vibrations

  23. SR loss sources (2/2) Telescope vibrations: Main influence on Tip-Tilt modes but other excitations detected on high order modes Vibrations not compensated for: out of the NAOS temporal bandwidth Strehl loss estimated to 10 %

  24. Differential aberrations in CONICA and dichroics At 1.09 mm SR= 56% SR =66% With pre-compensation by NAOS deformable mirror No compensation At 2.15 mm SR = 89 % SR = 93 % • Without turbulence, SR ~ 93 % in K with pre-compensation

  25. 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 !

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