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First light for the GRAVITY+ adaptive optics: extreme adaptive optics for the very large telescope interferometer

First light for the GRAVITY+ adaptive optics: extreme adaptive optics for the very large telescope interferometer
First light for the GRAVITY+ adaptive optics: extreme adaptive optics for the very large telescope interferometer
GRAVITY+ improves by orders of magnitude the sensitivity, sky-coverage and contrast of the Very Large Telescope Interferometer (VLTI). A central part of this project is the development of Gravity Plus Adaptive Optics (GPAO), a dedicated high-order and laser-guide star Adaptive Optics (AO) system for VLTI. GPAO consists of four state-of-the-art AO systems equipping all 8m-class Unit Telescopes (UTs) for the wavefront correction of the VLTI instruments. It offers both visible and infrared Natural Guide Star (NGS) and Laser Guide Star (LGS) operations. The paper presents the design, operations and performances of GPAO. We illustrate the improvement brought by GPAO with interferometric observations obtained during the commissioning of the NGS mode end-2024. These science results include the first optical interferometry observations of a redshift $z\sim4$ quasar, the spectroscopy of a cool brown-dwarf with magnitude $K\sim 21.0$, the first observations of a Class I young star with GRAVITY, and the first sub-micro arcsecond differential astrometry in the optical. Together with the entire GRAVITY+ project, the implementation of GPAO is a true paradigm shift for observing the optical Universe at very high angular resolution.
astro-ph.IM
0004-6361
Allouche, F.
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Bailet, C.
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Benisty, M.
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Berdeu, A.
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Berger, J.-P.
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Berio, P.
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Bigioli, A.
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Blanchard, C.
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Boebion, O.
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Bonnet, H.
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Bourdarot, G.
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Bourget, P.
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Brandner, W.
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Brulé, J.
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Burgos, P.
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Carbillet, M.
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Correia, C.
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Barrer, B. Courtney
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Curaba, S.
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Davies, R.
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Defrère, D.
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Delboulbé, A.
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Dembet, R.
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Drescher, A.
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Eckart, A.
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Édouard, C.
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Eisenhauer, F.
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Otal, L. Esteras
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Fabricius, M.
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Feuchtgruber, H.
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Fédou, P.
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Finger, G.
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Schreiber, N.M. Förster
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Frahm, R.
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Garcia, E.
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Garcia, P.
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Lopez, R. Garcia
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Genzel, R.
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Gil, J.P.
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Gillessen, S.
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Gomes, T.
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Gonté, F.
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Gopinath, V.
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Gouvret, C.
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Graf, J.
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Hönig, S.
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Leftley, J.
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Sykes, C.
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et al.
Allouche, F.
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Bailet, C.
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Benisty, M.
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Berdeu, A.
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Berger, J.-P.
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Berio, P.
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Bigioli, A.
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Blanchard, C.
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Boebion, O.
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Bonnet, H.
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Bourdarot, G.
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Bourget, P.
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Brandner, W.
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Brulé, J.
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Burgos, P.
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Carbillet, M.
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Correia, C.
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Barrer, B. Courtney
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Curaba, S.
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Davies, R.
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Defrère, D.
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Delboulbé, A.
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Delplancke, F.
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Dembet, R.
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Drescher, A.
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Dubost, N.
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Eckart, A.
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Édouard, C.
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Eisenhauer, F.
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Otal, L. Esteras
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Fabricius, M.
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Feuchtgruber, H.
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Fédou, P.
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Finger, G.
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Schreiber, N.M. Förster
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Frahm, R.
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Garcia, E.
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Garcia, P.
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Lopez, R. Garcia
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Genzel, R.
1ecd6228-ad0c-4fb5-a97f-28afeb78dc86
Gil, J.P.
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Gillessen, S.
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Gomes, T.
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Gonté, F.
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Gopinath, V.
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Gouvret, C.
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Graf, J.
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Hönig, S.
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Leftley, J.
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Sykes, C.
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Allouche, F., Bailet, C. and Benisty, M. , et al. (2026) First light for the GRAVITY+ adaptive optics: extreme adaptive optics for the very large telescope interferometer. A&A, 707, [A115]. (doi:10.1051/0004-6361/202555666).

Record type: Article

Abstract

GRAVITY+ improves by orders of magnitude the sensitivity, sky-coverage and contrast of the Very Large Telescope Interferometer (VLTI). A central part of this project is the development of Gravity Plus Adaptive Optics (GPAO), a dedicated high-order and laser-guide star Adaptive Optics (AO) system for VLTI. GPAO consists of four state-of-the-art AO systems equipping all 8m-class Unit Telescopes (UTs) for the wavefront correction of the VLTI instruments. It offers both visible and infrared Natural Guide Star (NGS) and Laser Guide Star (LGS) operations. The paper presents the design, operations and performances of GPAO. We illustrate the improvement brought by GPAO with interferometric observations obtained during the commissioning of the NGS mode end-2024. These science results include the first optical interferometry observations of a redshift $z\sim4$ quasar, the spectroscopy of a cool brown-dwarf with magnitude $K\sim 21.0$, the first observations of a Class I young star with GRAVITY, and the first sub-micro arcsecond differential astrometry in the optical. Together with the entire GRAVITY+ project, the implementation of GPAO is a true paradigm shift for observing the optical Universe at very high angular resolution.

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More information

Accepted/In Press date: 25 September 2025
e-pub ahead of print date: 11 March 2026
Keywords: astro-ph.IM

Identifiers

Local EPrints ID: 511745
URI: http://eprints.soton.ac.uk/id/eprint/511745
ISSN: 0004-6361
PURE UUID: 1e967550-2a17-498b-a779-e79c72432d87
ORCID for C. Sykes: ORCID iD orcid.org/0000-0003-3819-3023

Catalogue record

Date deposited: 01 Jun 2026 16:31
Last modified: 02 Jun 2026 02:02

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Contributors

Author: F. Allouche
Author: C. Bailet
Author: M. Benisty
Author: A. Berdeu
Author: J.-P. Berger
Author: P. Berio
Author: A. Bigioli
Author: C. Blanchard
Author: O. Boebion
Author: H. Bonnet
Author: G. Bourdarot
Author: P. Bourget
Author: W. Brandner
Author: J. Brulé
Author: P. Burgos
Author: M. Carbillet
Author: C. Correia
Author: B. Courtney Barrer
Author: S. Curaba
Author: R. Davies
Author: D. Defrère
Author: A. Delboulbé
Author: F. Delplancke
Author: R. Dembet
Author: A. Drescher
Author: N. Dubost
Author: A. Eckart
Author: C. Édouard
Author: F. Eisenhauer
Author: L. Esteras Otal
Author: M. Fabricius
Author: H. Feuchtgruber
Author: P. Fédou
Author: G. Finger
Author: N.M. Förster Schreiber
Author: R. Frahm
Author: E. Garcia
Author: P. Garcia
Author: R. Garcia Lopez
Author: R. Genzel
Author: J.P. Gil
Author: S. Gillessen
Author: T. Gomes
Author: F. Gonté
Author: V. Gopinath
Author: C. Gouvret
Author: J. Graf
Author: S. Hönig
Author: J. Leftley
Author: C. Sykes ORCID iD
Corporate Author: et al.

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