Dr. Julien H. Girard Profile

Dr. Julien H. Girard

Scientist at Space Telescope Science Institute

SPIE Involvement:

Author

Area of Expertise:

Astronomy , Adaptive Optics , Instrumentation , High Angular Resolution Techniques , Star and Planet Formation , High Contrast Imaging

Websites:

Personal Website | Company Website

Profile Summary

Julien H. Girard is currently an AURA (Full) Scientist at the Space Telescope Science Institute (STScI) in Baltimore, Maryland. Girard supports two flagship missions: JWST/NIRCam and Roman. He leads effort with coronagraphy / high contrast imaging since mid 2017. Member of the long term senior research staff at STScI, Girard's research focuses on constraining the formation and migration mechanisms of giant extra-solar planets in young and dusty circumstellar environments (e.g disks) through direct imaging. Girard uses high angular/contrast imaging techniques extensively, mainly in the infrared, from the ground and space.

From 2009 to 2017 Girard was Operations Staff Astronomer at ESO Chile. Adaptive Optics specialist, he was the lead Instrument Scientist of VLT/SPHERE and NACO. After completing a Master in Instrumentation Physics from the University of Utah in 2000, he obtained a 2nd Master in Astrophysics at UJF/IPAG ( Grenoble) the next year and his PhD in 2005 (UCBL/Observatoire de Lyon), validating the concept of polychromatic laser guide star on-sky.
Before ESO, Girard spent 3 years in Mexico City as a Postdoctoral Fellow at UNAM and as Assistant Professor at IPN. Enjoying public outreach, Julien is one of the ESO Photo Ambassadors.

Publications (53)

Proceedings Article | 29 August 2022 Open Access

Open Access

Presentation

JWST: Early results and Instruments

Jonathan Gardner, Nora Lützgendorf, Julien Girard, Sarah Kendrew, Swara Ravindranath

Proceedings Volume 12180, 1218003 (2022) https://doi.org/10.1117/12.2646871

Read Abstract +

Proceedings Article | 27 August 2022 Presentation + Paper

Presentation + Paper

Nancy Grace Roman Space Telescope coronagraph instrument observation calibration plan

Robert Zellem, Bijan Nemati, Guillermo Gonzalez, Marie Ygouf, Vanessa Bailey, Eric Cady, M. Mark Colavita, Sergi Hildebrandt, Erin Maier, Bertrand Mennesson, Lindsey Payne, Neil Zimmerman, Ruslan Belikov, Robert De Rosa, John Debes, Ewan Douglas, Julien Girard, Tyler Groff, Jeremy Kasdin, Patrick Lowrance, Bruce Macintosh, Daniel Ryan, Carey Weisberg

Proceedings Volume 12180, 121801Z (2022) https://doi.org/10.1117/12.2627567

KEYWORDS: Calibration, Stars, Coronagraphy, Planets, Sensors, Polarization, Point spread functions, Error analysis, Signal to noise ratio, Uranus

Read Abstract +

Proceedings Article | 27 August 2022 Paper

Paper

Performance of near-infrared high-contrast imaging methods with JWST from commissioning

Jens Kammerer, Julien Girard, Aarynn Carter, Marshall Perrin, Rachel Cooper, Deepashri Thatte, Thomas Vandal, Jarron Leisenring, Jason Wang, William Balmer, Anand Sivaramakrishnan, Laurent Pueyo, Kimberly Ward-Duong, Ben Sunnquist, Jéa Adams Redai

Proceedings Volume 12180, 121803N (2022) https://doi.org/10.1117/12.2628865

KEYWORDS: Coronagraphy, James Webb Space Telescope, Target acquisition, Data processing, Telescopes, Calibration, Interferometry, Image registration

Read Abstract +

The James Webb Space Telescope (JWST) will revolutionize the field of high-contrast imaging and enable both the direct detection of Saturn-mass planets and the characterization of substellar companions in the mid-infrared. While JWST will feature unprecedented sensitivity, angular resolution will be the key factor when competing with ground-based telescopes. Here, we aim to characterize the performance of several extreme angular resolution imaging techniques available with JWST in the 3–5 µm regime based on data taken during the instrument commissioning. Firstly, we introduce custom tools to simulate, reduce, and analyze JWST NIRCam and MIRI coronagraphy data and use these tools to extract companion detection limits from on-sky NIRCam round and bar mask coronagraphy observations. Secondly, we present on-sky JWST NIRISS aperture masking interferometry (AMI) and kernel phase imaging (KPI) observations from which we extract companion detection limits using the publicly available fouriever tool. Scaled to a total integration time of one hour and a target of the brightness of AB Dor (W1 ≈ 4.4 mag, W2 ≈ 3.9 mag), we find that NIRISS AMI and KPI reach contrasts of ∼ 7–8 mag at ∼ 70 mas and ∼ 9 mag at ∼ 200 mas. Beyond ∼ 250 mas, NIRCam coronagraphy reaches deeper contrasts of ∼ 13 mag at ∼ 500 mas and ∼ 15 mag at ∼ 2 arcsec. While the bar mask performs ∼ 1 mag better than the round mask at small angular separations ≲ 0.75 arcsec, it is the other way around at large angular separations ≳ 1.5 arcsec. Moreover, the round mask gives access to the full 360 deg field-of-view which is beneficial for the search of new companions. We conclude that already during the instrument commissioning, JWST high-contrast imaging in the L- and M-bands performs close to its predicted limits and is a factor of ∼ 10 times better at large separations than the best ground-based instruments operating at similar wavelengths despite its < 2 times smaller collecting area.

Proceedings Article | 27 August 2022 Poster + Presentation + Paper

Poster + Presentation + Paper

JWST/NIRCam coronagraphy: commissioning and first on-sky results

Julien Girard, Jarron Leisenring, Jens Kammerer, Mario Gennaro, Marcia Rieke, John Stansberry, Armin Rest, Eiichi Egami, Ben Sunnquist, Martha Boyer, Alicia Canipe, Matteo Correnti, Bryan Hilbert, Marshall Perrin, Laurent Pueyo, Remi Soummer, Marsha Allen, Howard Bushouse, Jonathan Aguilar, Brian Brooks, Dan Coe, Audrey DiFelice, David Golimowski, George Hartig, Dean Hines, Anton Koekemoer, Bryony Nickson, Nikolay Nikolov, Vera Kozhurina-Platais, Nor Pirzkal, Massimo Robberto, Anand Sivaramakrishnan, Sangmo Tony Sohn, Randal Telfer, Chi Rai Wu, Thomas Beatty, Michael Florian, Kevin Hainline, Doug Kelly, Karl Misselt, Everett Schlawin, Fengwu Sun, Christina Williams, Christopher Willmer, Christopher Stark, Marie Ygouf, Aarynn Carter, Charles Beichman, Thomas Greene, Thomas Roellig, John Krist, Jéa Adams Redai, Jason Wang, Charles Clark, Dan Lewis, Malcolm Ferry

Proceedings Volume 12180, 121803Q (2022) https://doi.org/10.1117/12.2629636

KEYWORDS: Coronagraphy, Stars, James Webb Space Telescope, Point spread functions, Distortion, Telescopes, Signal to noise ratio, Calibration, Target acquisition, Exoplanets, Astronomical imaging, Near infrared, Direct methods, Astronomical instrumentation

Read Abstract +

Proceedings Article | 27 August 2022 Presentation + Paper

Presentation + Paper

Direct imaging and spectroscopy of exoplanetary systems with the JWST early release science program

Sasha Hinkley, Aarynn Carter, Shrishmoy Ray, Beth Biller, Andrew Skemer, Elodie Choquet, Maxwell Millar-Blanchaer, Stephanie Sallum, Brittany Miles, Niall Whiteford, Polychronis Patapis, Marshall Perrin, Laurent Pueyo, Karl Stapelfeldt, Jason Wang, Kimberly Ward-Duong, Julien Girard, Dean Hines, Jens Kammerer, Jarron Leisenring, Yifan Zhou, Michael Meyer, Michael Liu, Mickael Bonnefoy, Simon Petrus, Mariangela Bonavita, Gael Chauvin, Christine Chen, Thayne Currie, Kielan K. Hoch, Cecilia Lazzoni, Elisabeth Matthews, Michael McElwain, Isabel Rebollido, Emily Rickman, Glenn Schneider, Anand Sivaramakrishnan, Jordan Stone

Proceedings Volume 12180, 121800S (2022) https://doi.org/10.1117/12.2629919

KEYWORDS: James Webb Space Telescope, Coronagraphy, Planets, Exoplanets, Imaging systems, Astronomy, Imaging spectroscopy, Spectroscopy, Stars, Calibration

Read Abstract +

Proceedings Article | 3 September 2021 Presentation + Paper

Presentation + Paper

Simulating JWST high contrast observations with PanCAKE

Aarynn Carter, Andrew J. Skemer, Camilla Danielski, Jarron Leisenring, Jason Wang, Kyle Van Gorkom, Brian York, Jea Adams, Beth Biller, Julien Girard, Sasha Hinkley, Bryony Nickson, Marshall Perrin, Laurent Pueyo

Proceedings Volume 11823, 118230H (2021) https://doi.org/10.1117/12.2594501

KEYWORDS: James Webb Space Telescope, Point spread functions, Coronagraphy, Wavefronts, Computer simulations, Device simulation, Target acquisition, Telescopes, Sensors, Exoplanets

Read Abstract +

SPIE Journal Paper | 5 August 2021 Open Access

Open Access

Lessons learned from SPHERE for the astrometric strategy of the next generation of exoplanet imaging instruments

Anne-Lise Maire, Maud Langlois, Philippe Delorme, Gaël Chauvin, Raffaele Gratton, Arthur Vigan, Julien Girard, Zahed Wahhaj, Jörg-Uwe Pott, Leonard Burtscher, Anthony Boccaletti, Alexis Carlotti, Thomas Henning, Matthew Kenworthy, Pierre Kervella, Emily Rickman, Tobias O. Schmidt

JATIS, Vol. 7, Issue 03, 035004, (August 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.3.035004

KEYWORDS: Optical spheres, Calibration, Stars, Distortion, Coronagraphy, Exoplanets, Telescopes, Imaging systems, Adaptive optics, Sensors

Read Abstract +

SPIE Journal Paper | 28 May 2021 Open Access

Open Access

Community exoplanet imaging data challenge for Roman CGI and starshade rendezvous

Margaret Turnbull, Neil Zimmerman, Julien Girard, Sergi R. Hildebrandt, Zhexing Li, Ell Bogat, Junellie Gonzalez-Quiles, Christopher Stark, Avi Mandell, Tiffany Meshkat, Stephen Kane

JATIS, Vol. 7, Issue 02, 021218, (May 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021218

KEYWORDS: Planets, Exoplanets, Imaging systems, Signal to noise ratio, Stars, Coronagraphy, Telescopes, Data modeling, Point spread functions, Sensors

Read Abstract +

Operating in an unprecedented contrast regime (10 − 7 to 10 − 9), the Roman Coronagraph Instrument (CGI) will serve as a pathfinder for key technologies needed for future Earth-finding missions such as HabEx and LUVOIR. The Roman Exoplanet Imaging Data Challenge (Roman EIDC) was a community engagement effort that tasked participants with extracting exoplanets and their orbits for a 47-UMa-like target star given: (1) 15 years of simulated precursor radial velocity (RV) data and (2) six epochs of simulated imaging taken over the course of the Roman mission. Led by the Turnbull CGI Science Investigation Team, the Roman EIDC was preceded by four tutorial “hack-a-thon” events in Baltimore, Pasadena, New York City, and Tokyo. The Roman EIDC officially launched in October 2019 and ran for 8 months, offering a unique opportunity for exoplanet scientists of all experience levels to get acquainted with realistic near-future imaging data. The Roman EIDC simulated images include four epochs with CGI’s Hybrid Lyot Coronagraph (HLC) plus two epochs with a starshade (SS) assumed to arrive as part of a Starshade Rendezvous later in the mission. We focus on our in-house analysis of the outermost planet “d,” for which the SS’s higher throughput and lower noise floor present a factor of ∼4 improvement in the signal-to-noise ratio over the narrow-field HLC. We find that, although the RV detection was marginal for planet d, the precursor RV data enabled the mass and orbit to be constrained with only two epochs of SS imaging. Including the HLC images in the analysis results in improved measurements over RV + SS alone, with the greatest gains resulting from images taken at epochs near maximum elongation. Combining the two epochs of SS imaging with the RV + HLC data resulted in a factor of ∼2 better orbit and mass determinations over RV + HLC alone. In summary, the Roman CGI, combined with precursor RV data and latermission SS imaging, forms a powerful trifecta in detecting exoplanets and determining their masses, albedos, and system configurations. While the Roman CGI will break new scientific and technological ground with direct imaging of giant exoplanets within ∼5 AU of V ˜ 5 and brighter stars, a Roman Starshade Rendezvous mission would additionally enable the detection of planets out to ∼8 AU in those systems.

Proceedings Article | 23 December 2020 Poster + Paper

Poster + Paper

Data processing for high-contrast imaging with the James Webb Space Telescope

Marie Ygouf, Graça Rocha, Charles Beichman, Alexandra Greenbaum, Jarron Leisenring, Matthew De Furio, Michael Meyer, Julien Girard, Laurent Pueyo, Marshall Perrin, Taichi Uyama, Joseph Green, Jeffrey Jewell

Proceedings Volume 11443, 114433N (2020) https://doi.org/10.1117/12.2561628

KEYWORDS: James Webb Space Telescope, Data processing, Image processing, Human-computer interaction, Exoplanets, Planets, Point spread functions, Control systems, Coronagraphy, Environmental sensing

Read Abstract +

Proceedings Article | 16 December 2020 Presentation + Paper

Presentation + Paper

Planet formation with all flavors of adaptive optics: VLT/MUSE’s laser tomography adaptive optics to directly image young accreting exoplanets

Julien Girard, Sebastiaan Haffert, Jaehan Bae, Peter Zeidler, Jozua de Boer, Alexander Bohn, Rob van Holstein, Jarle Brinchmann, Ignas Snellen, Rolan Bacon, Christoph Keller

Proceedings Volume 11448, 1144808 (2020) https://doi.org/10.1117/12.2560075

KEYWORDS: Planets, Adaptive optics, Stars, Spatial resolution, Planetary systems, Near infrared, Spectrographs, Point spread functions, Image resolution, Iterated function systems

Read Abstract +

Proceedings Article | 16 December 2020 Presentation + Paper

Presentation + Paper

The ExoGRAVITY project: using single mode interferometry to characterize exoplanets

S. Lacour, J. Wang, M. Nowak, L. Pueyo, F. Eisenhauer, A.-M. Lagrange, P. Mollière, R. Abuter, A. Amorin, R. Asensio-Torres, M. Bauböck, M. Benisty, J. P. Berger, H. Beust, S. Blunt, A. Boccaletti, A. Bohn, M. Bonnefoy, H. Bonnet, W. Brandner, F. Cantalloube, P. Caselli, B. Charnay, G. Chauvin, E. Choquet, V. Christiaens, Y. Clénet, A. Cridland, P. T. de Zeeuw, R. Dembet, J. Dexter, A. Drescher, G. Duvert, F. Gao, P. Garcia, R. Garcia Lopez, T. Gardner, E. Gendron, R. Genzel, S. Gillessen, J. H. Girard, X. Haubois, G. Heißel, T. Henning, S. Hinkley, S. Hippler, M. Horrobin, M. Houllé, Z. Hubert, A. Jiménez-Rosales, L. Jocou, J. Kammerer, M. Keppler, P. Kervella, L. Kreidberg, V. Lapeyrère, J.-B. Le Bouquin, P. Léna, D. Lutz, A.-L. Maire, A. Mérand, J. D. Monnier, D. Mouillet, A. Muller, E. Nasedkin, T. Ott, G. P. P. L. Otten, C. Paladini, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, J. Rameau, L. Rodet, G. Rodriguez-Coira, G. Rousset, J. Shangguan, T. Shimizu, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, T. Stolker, E. van Dishoeck, A. Vigan, F. Vincent, S. D. von Fellenberg, K. Ward-Duong, F. Widmann, E. Wieprecht, E. Wiezorrek, J. Woillez

Proceedings Volume 11446, 114460O (2020) https://doi.org/10.1117/12.2561667

KEYWORDS: Interferometry, Exoplanets

Read Abstract +

Proceedings Article | 15 December 2020 Poster + Presentation + Paper

Poster + Presentation + Paper

The Roman exoplanet imaging data challenge: a major community engagement effort

Julien Girard, Ell Bogat, Junellie Gonzalez-Quiles, Sergi Hildebrandt, Stephen Kane, Zhexing Li, Margaret Turnbull, Christopher Stark, Avi Mandell, Tiffany Meshkat, Neil Zimmerman

Proceedings Volume 11443, 1144337 (2020) https://doi.org/10.1117/12.2561736

KEYWORDS: Exoplanets, Coronagraphy, Planets, Imaging systems, Stars, Point spread functions, Astrophysics, Contamination, Light, Wavefronts

Read Abstract +

Proceedings Article | 17 August 2018 Paper

Paper

Making good use of JWST's coronagraphs: tools and strategies from a user's perspective

Julien Girard, William Blair, Brian Brooks, Keira Brooks, Robert Brown, Howard Bushouse, Alicia Canipe, Christine Chen, Matteo Correnti, J. Brendan Hagan, Bryan Hilbert, Dean Hines, Jarron Leisenring, Joseph Long, Bryony Nickson, Marshall Perrin, Klaus Pontoppidan, Laurent Pueyo, Abhijith Rajan, Adric Riedel, Remi Soummer, John Stansberry, Christopher Stark, Kyle Van Gorkom, Brian York

Proceedings Volume 10698, 106983V (2018) https://doi.org/10.1117/12.2314198

KEYWORDS: Coronagraphy, Point spread functions, James Webb Space Telescope, Stars, Signal to noise ratio, Exoplanets, Calibration, Visibility, Space telescopes, Device simulation

Read Abstract +

Proceedings Article | 9 August 2018 Paper

Paper

Lessons for WFIRST CGI from ground-based high-contrast systems

Vanessa Bailey, Michael Bottom, Eric Cady, Faustine Cantalloube, Jozua de Boer, Tyler Groff, John Krist, Maxwell Millar-Blanchaer, Arthur Vigan, Jeffrey Chilcote, Elodie Choquet, Robert De Rosa, Julien Girard, Olivier Guyon, Brian Kern, Anne-Marie Lagrange, Bruce Macintosh, Jared Males, Christian Marois, Tiffany Meshkat, Julien Milli, Mamadoue N'Diaye, Henry Ngo, Eric Nielsen, Jason Rhodes, Garreth Ruane, Rob van Holstein, Jason Wang, Wenhao Xuan

Proceedings Volume 10698, 106986P (2018) https://doi.org/10.1117/12.2313820

KEYWORDS: Calibration, Stars, Point spread functions, Polarization, Coronagraphy, Satellites, Telescopes, Planets, Polarimetry, Imaging spectroscopy

Read Abstract +

Proceedings Article | 6 August 2018 Presentation + Paper

Presentation + Paper

Updated optical modeling of JWST coronagraph performance contrast, stability, and strategies

Marshall Perrin, Laurent Pueyo, Kyle Van Gorkom, Keira Brooks, Abhijith Rajan, Julien Girard, Charles-Philippe Lajoie

Proceedings Volume 10698, 1069809 (2018) https://doi.org/10.1117/12.2313552

KEYWORDS: Point spread functions, Coronagraphy, Wavefronts, James Webb Space Telescope, Calibration, Observatories, Telescopes, Exoplanets, Wavefront aberrations

Read Abstract +

Proceedings Article | 10 July 2018 Presentation + Paper

Presentation + Paper

Low wind effect on VLT/SPHERE: impact, mitigation strategy, and results

J. Milli, M. Kasper, P. Bourget, C. Pannetier, D. Mouillet, J.-F. Sauvage, C. Reyes, T. Fusco, F. Cantalloube, K. Tristam, Z. Wahhaj, J.-L. Beuzit, J. Girard, D. Mawet, A. Telle, A. Vigan, M. N'Diaye

Proceedings Volume 10703, 107032A (2018) https://doi.org/10.1117/12.2311499

KEYWORDS: Telescopes, Adaptive optics, Point spread functions, Optical coatings, Wind measurement, Coronagraphy, Diffraction

Read Abstract +

Proceedings Article | 9 July 2018 Presentation

Presentation

Around the world: status and prospects with the infrared vortex coronagraph (Conference Presentation)

Olivier Absil, Mikael Karlsson, Dimitri Mawet, Brunella Carlomagno, Valentin Christiaens, Denis Defrère, Christian Delacroix, Julien Girard, Carlos Gomez Gonzalez, Serge Habraken, Philip Hinz, Elsa Huby, Aissa Jolivet, Markus Kasper, Hans-Ulrich Kaufl, Matthew Kenworthy, Keith Matthews, Julien Milli, Gilles Orban de Xivry, Eric Pantin, Pierre Piron, Maddalena Reggiani, A.J. Eldorado Riggs, Eugene Serabyn, Jean Surdej, Ernesto Vargas Catalan

Proceedings Volume 10702, 107020T (2018) https://doi.org/10.1117/12.2312783

KEYWORDS: Coronagraphy, Infrared radiation, Mid-IR, Infrared cameras, Observatories, Keck Observatory, Data processing, Planets, Cameras, K band

Read Abstract +

Proceedings Article | 12 September 2017 Presentation + Paper

Presentation + Paper

Combining angular differential imaging and accurate polarimetry with SPHERE/IRDIS to characterize young giant exoplanets

Rob van Holstein, Frans Snik, Julien Girard, Jozua de Boer, C. Ginski, Christoph Keller, Daphne Stam, Jean-Luc Beuzit, David Mouillet, Markus Kasper, Maud Langlois, Alice Zurlo, Remco de Kok, Arthur Vigan

Proceedings Volume 10400, 1040015 (2017) https://doi.org/10.1117/12.2272554

KEYWORDS: Polarization, Polarimetry, Planets, Signal detection, Principal component analysis, Exoplanets, Telescopes, Stars, Solids, Speckle

Read Abstract +

Young giant exoplanets emit infrared radiation that can be linearly polarized up to several percent. This linear polarization can trace: 1) the presence of atmospheric cloud and haze layers, 2) spatial structure, e.g. cloud bands and rotational flattening, 3) the spin axis orientation and 4) particle sizes and cloud top pressure. We introduce a novel high-contrast imaging scheme that combines angular differential imaging (ADI) and accurate near-infrared polarimetry to characterize self-luminous giant exoplanets. We implemented this technique at VLT/SPHEREIRDIS and developed the corresponding observing strategies, the polarization calibration and the data-reduction approaches. The combination of ADI and polarimetry is challenging, because the field rotation required for ADI negatively affects the polarimetric performance. By combining ADI and polarimetry we can characterize planets that can be directly imaged with a very high signal-to-noise ratio. We use the IRDIS pupil-tracking mode and combine ADI and principal component analysis to reduce speckle noise. We take advantage of IRDIS’ dual-beam polarimetric mode to eliminate differential effects that severely limit the polarimetric sensitivity (flat-fielding errors, differential aberrations and seeing), and thus further suppress speckle noise. To correct for instrumental polarization effects, we apply a detailed Mueller matrix model that describes the telescope and instrument and that has an absolute polarimetric accuracy ≤ 0.1%. Using this technique we have observed the planets of HR 8799 and the (sub-stellar) companion PZ Tel B. Unfortunately, we do not detect a polarization signal in a first analysis. We estimate preliminary 1σ upper limits on the degree of linear polarization of ∼ 1% and ∼ 0.1% for the planets of HR 8799 and PZ Tel B, respectively. The achieved sub-percent sensitivity and accuracy show that our technique has great promise for characterizing exoplanets through direct-imaging polarimetry

Proceedings Article | 2 September 2016 Paper

Paper

ABISM: an interactive image quality assessment tool for adaptive optics instruments

Julien Girard, Martin Tourneboeuf

Proceedings Volume 9909, 99097V (2016) https://doi.org/10.1117/12.2231493

KEYWORDS: Image quality, Point spread functions, Telescopes, Observatories, Adaptive optics, Stars, Photometry, Electroluminescent displays, Signal to noise ratio, Strontium

Read Abstract +

Proceedings Article | 16 August 2016 Paper

Paper

Interferometric direct imaging properties of a BIGRE-DAM device in laboratory

Fabien Patru, Jacopo Antichi, Patrick Rabou, Enrico Giro, Jacopo Farinato, Raffaele Gratton, Daniele Vassallo, Christophe Verinaud, Denis Mourard, Julien Girard

Proceedings Volume 9907, 99072U (2016) https://doi.org/10.1117/12.2233108

KEYWORDS: Point spread functions, Interferometry, Spatial filters, Image filtering, Large telescopes, Optical filters, Wavefronts, Spatial frequencies, Diffraction, Single mode fibers

Read Abstract +

Proceedings Article | 9 August 2016 Paper

Paper

Pushing down with the contrast: scientific performances with SPHERE-IFS

R. Claudi, J. Antichi, A. Baruffolo, P. Bruno, E. Cascone, V. DeCaprio, M. DePascale, S. Desidera, V. D'Orazi, D. Fantinel, G. Farisato, E. Giro, R. Gratton, L. Lessio, A.L. Maire, D. Mesa, B. Salasnich, S. Scuderi, E. Sissa, M. Turatto, A. Zurlo, JL Beuzit, A. Boccaletti, G. Chauvin, K. Dohlen, G. Finger, J. Girard, M. Kasper, N. Hubin, M. Langlois, J. L. Lizon, D. Mouillet, P. Puget, F. Wildi

Proceedings Volume 9908, 99083H (2016) https://doi.org/10.1117/12.2232827

KEYWORDS: Iterated function systems, Optical spheres, Imaging systems, Exoplanets, Stars, Polarization, Visible radiation, Iterated function systems, Optical spheres, Principal component analysis, Coronagraphy, Planets

Read Abstract +

Proceedings Article | 9 August 2016 Paper

Paper

Three years of harvest with the vector vortex coronagraph in the thermal infrared

Olivier Absil, Dimitri Mawet, Mikael Karlsson, Brunella Carlomagno, Valentin Christiaens, Denis Defrère, Christian Delacroix, Bruno Femenía Castella, Pontus Forsberg, Julien Girard, Carlos Gómez González, Serge Habraken, Philip Hinz, Elsa Huby, Aïssa Jolivet, Keith Matthews, Julien Milli, Gilles Orban de Xivry, Eric Pantin, Pierre Piron, Maddalena Reggiani, Garreth Ruane, Gene Serabyn, Jean Surdej, Konrad R. Tristram, Ernesto Vargas Catalán, Olivier Wertz, Peter Wizinowich

Proceedings Volume 9908, 99080Q (2016) https://doi.org/10.1117/12.2233289

KEYWORDS: Thermography, Infrared radiation, Coronagraphy, Stars, L band, Planets, Etching, Diamond, Telescopes, Cameras

Read Abstract +

Proceedings Article | 9 August 2016 Paper

Paper

SPHERE on-sky performance compared with budget predictions

Kjetil Dohlen, Arthur Vigan, David Mouillet, François Wildi, Jean-François Sauvage, Thierry Fusco, Jean-Luc Beuzit, Pascal Puget, David Le Mignant, Ronald Roelfsema, Johan Pragt, Hans Martin Schmid, Raffaele Gratton, Dino Mesa, Riccardo Claudi, Maud Langlois, Anne Costille, Emmanuel Hugot, Jared O'Neil, Juan Carlos Guerra, Mamadou N'Diaye, Julien Girard, Dimitri Mawet, Gerard Zins

Proceedings Volume 9908, 99083D (2016) https://doi.org/10.1117/12.2233953

KEYWORDS: Wavefronts, Optical spheres, Cameras, Actuators, Calibration, Coronagraphy, Mirrors, Infrared radiation, Sensors, Iterated function systems

Read Abstract +

Proceedings Article | 9 August 2016 Paper

Paper

SPHERE IRDIS and IFS astrometric strategy and calibration

Anne-Lise Maire, Maud Langlois, Kjetil Dohlen, Anne-Marie Lagrange, Raffaele Gratton, Gaël Chauvin, Silvano Desidera, Julien Girard, Julien Milli, Arthur Vigan, Gerard Zins, Philippe Delorme, Jean-Luc Beuzit, Riccardo Claudi, Markus Feldt, David Mouillet, Pascal Puget, Massimo Turatto, François Wildi

Proceedings Volume 9908, 990834 (2016) https://doi.org/10.1117/12.2233013

KEYWORDS: Optical spheres, Iterated function systems, Calibration, Distortion, Planets, Electroluminescent displays, Coronagraphy, Stars, Data centers, Error analysis

Read Abstract +

Proceedings Article | 4 August 2016 Paper

Paper

Sparse aperture masking with SPHERE

Anthony Cheetham, Julien Girard, Sylvestre Lacour, Guillaume Schworer, Xavier Haubois, Jean-Luc Beuzit

Proceedings Volume 9907, 99072T (2016) https://doi.org/10.1117/12.2231983

KEYWORDS: Optical spheres, Interferometry, Visible radiation, Adaptive optics, Imaging systems, Wavefronts, Iterated function systems, Point spread functions, Calibration, Polarimetry

Read Abstract +

Proceedings Article | 27 July 2016 Paper

Paper

Speckle lifetime in XAO coronagraphic images: temporal evolution of SPHERE coronagraphic images

J. Milli, T. Banas, D. Mouillet, D. Mawet, J. Girard, A. Vigan, A. Boccaletti, M. Kasper, Zahed Wahhaj, A. M. Lagrange, J.-L. Beuzit, T. Fusco, J.-F. Sauvage, R. Galicher

Proceedings Volume 9909, 99094Z (2016) https://doi.org/10.1117/12.2231703

KEYWORDS: Adaptive optics, Speckle, Optical spheres, Point spread functions, Adaptive optics, Optical spheres, Coronagraphy, Sensors, Stars, Telescopes, Lamps, Camera shutters

Read Abstract +

Proceedings Article | 27 July 2016 Paper

Paper

ZELDA, a Zernike wavefront sensor for the fine measurement of quasi-static aberrations in coronagraphic systems: concept studies and results with VLT/SPHERE

M. N'Diaye, A. Vigan, K. Dohlen, J.-F. Sauvage, A. Caillat, A. Costille, J. H. Girard, J.-L. Beuzit, T. Fusco, P. Blanchard, J. Le Merrer, D. Le Mignant, F. Madec, G. Moreaux, D. Mouillet, P. Puget, G. Zins

Proceedings Volume 9909, 99096S (2016) https://doi.org/10.1117/12.2232463

KEYWORDS: Wavefront sensors, Exoplanets, Exoplanets, Sensors, Wavefront sensors, Wavefronts, Coronagraphy, Optical spheres, Calibration, Point spread functions, Actuators, Photomasks

Read Abstract +

Proceedings Article | 26 July 2016 Paper

Paper

SAXO, the SPHERE extreme AO system: on-sky final performance and future improvements

T. Fusco, J.-F. Sauvage, D. Mouillet, A. Costille, C. Petit, J.-L. Beuzit, K. Dohlen, J. Milli, J. Girard, M. Kasper, A. Vigan, M. Suarez, C. Soenke, M. Downing, M. N'Diaye, P. Baudoz, A. Sevin, A. Baruffolo, H.-M. Schmid, B. Salasnich, E. Hugot, N. Hubin

Proceedings Volume 9909, 99090U (2016) https://doi.org/10.1117/12.2233319

KEYWORDS: Adaptive optics, Optical spheres, Exoplanets, Stars, Adaptive optics, Coronagraphy, Telescopes, Calibration, Near infrared, Image quality, Control systems

Read Abstract +

Proceedings Article | 26 July 2016 Paper

Paper

Tackling down the low wind effect on SPHERE instrument

Jean-François Sauvage, Thierry Fusco, Masen Lamb, Julien Girard, Martin Brinkmann, Andres Guesalaga, Peter Wizinowich, Jared O'Neal, Mamadou N'Diaye, Arthur Vigan, David Mouillet, Jean-Luc Beuzit, Markus Kasper, Miska Le Louarn, Julien Milli, Kjetil Dohlen, Benoît Neichel, Pierre Bourget, Pierre Haguenauer, Dimitri Mawet

Proceedings Volume 9909, 990916 (2016) https://doi.org/10.1117/12.2232459

KEYWORDS: Optical spheres, Adaptive optics, Planets, Stars, Exoplanets, Telescopes, Wind measurement, Spatial frequencies, Control systems, Radiative transfer

Read Abstract +

Proceedings Article | 11 July 2016 Paper

Paper

Training telescope operators and support astronomers at Paranal

Henri Boffin, Dimitri Gadotti, Joe Anderson, Andres Pino, Willem-Jan de Wit, Julien Girard

Proceedings Volume 9910, 991032 (2016) https://doi.org/10.1117/12.2232105

KEYWORDS: Astronomical telescopes, Telescopes, Adaptive optics, Interferometry, Observatories, Astronomy, Particle swarm optimization, Calibration, Optical interferometry, Infrared telescopes

Read Abstract +

Proceedings Article | 11 July 2016 Paper

Paper

Quality control and data flow operations of SPHERE

Wolfgang Hummel, Julien Girard, Julien Milli, Zahed Wahhaj, Lars Lundin, Arthur Vigan

Proceedings Volume 9910, 99102O (2016) https://doi.org/10.1117/12.2231423

KEYWORDS: Optical spheres, Control systems, Radio astronomy, Observatories, Systems engineering, Scanning transmission electron microscopy, Surgery, Software, Computing systems, Data storage

Read Abstract +

SPIE Journal Paper | 24 May 2016

SAXO: the extreme adaptive optics system of SPHERE (I) system overview and global laboratory performance

Cyril Petit, Anne Costille, David Mouillet, Jean-Luc Beuzit, Kjetil Dohlen, Markus Kasper, Marcos Suárez Valles, Christian Soenke, Andrea Baruffolo, Bernardo Salasnich, Sylvain Rochat, Enrico Fedrigo, Pierre Baudoz, Emmanuel Hugot, Arnaud Sevin, Denis Perret, François Wildi, Mark Downing, Philippe Feautrier, Pascal Puget, Arthur Vigan, Jared O’Neal, Julien Girard, Dimitri Mawet, Hans Martin Schmid, Ronald Roelfsema, Jean-Francois Sauvage, Thierry Fusco

JATIS, Vol. 2, Issue 02, 025003, (May 2016) https://doi.org/10.1117/12.10.1117/1.JATIS.2.2.025003

KEYWORDS: Optical spheres, Adaptive optics, Actuators, Turbulence, Coronagraphy, Point spread functions, Calibration, Mirrors, Telescopes, Observatories

Read Abstract +

Proceedings Article | 22 August 2014 Paper

Paper

Discretized aperture mapping with a micro-lenses array for interferometric direct imaging

Fabien Patru, Jacopo Antichi, Dimitri Mawet, Laurent Jolissaint, Marcel Carbillet, Julien Milli, Julien Girard, Patrick Rabou, Enrico Giro, Denis Mourard

Proceedings Volume 9148, 91485P (2014) https://doi.org/10.1117/12.2058594

KEYWORDS: Adaptive optics, Spatial frequencies, Interferometry, Spatial filters, Imaging systems, Point spread functions, Actuators, Wavefronts, Optical filters, Image filtering

Read Abstract +

Proceedings Article | 13 August 2014 Paper

Paper

Atmospheric parameter estimation from AO wavefront sensing data: application of the FADE method with NACO

Elisabeth Brunner, Julien Girard

Proceedings Volume 9148, 914861 (2014) https://doi.org/10.1117/12.2055614

KEYWORDS: Adaptive optics, Data modeling, Telescopes, Wavefront sensors, Atmospheric turbulence, Atmospheric modeling, Turbulence, Atmospheric sensing, Statistical analysis, Statistical modeling

Read Abstract +

Proceedings Article | 7 August 2014 Paper

Paper

Final performance and lesson-learned of SAXO, the VLT-SPHERE extreme AO: from early design to on-sky results

T. Fusco, J.-F. Sauvage, C. Petit, A. Costille, K. Dohlen, D. Mouillet, J.-L. Beuzit, M. Kasper, M. Suarez, C. Soenke, E. Fedrigo, M. Downing, P. Baudoz, A. Sevin, D. Perret, A. Barrufolo, B. Salasnich, P. Puget, F. Feautrier, S. Rochat, T. Moulin, A. Deboulbé, E. Hugot, A. Vigan, D. Mawet, J. Girard, N. Hubin

Proceedings Volume 9148, 91481U (2014) https://doi.org/10.1117/12.2055423

KEYWORDS: Adaptive optics, Optical spheres, Coronagraphy, Actuators, Point spread functions, Telescopes, Exoplanets, Speckle, Control systems, Sensors

Read Abstract +

Proceedings Article | 7 August 2014 Paper

Paper

Real-time Strehl and image quality performance estimator at Paranal Observatory

Dimitri Mawet, Alain Smette, Marc Sarazin, Harald Kuntschner, Julien Girard

Proceedings Volume 9148, 91484T (2014) https://doi.org/10.1117/12.2057263

KEYWORDS: Adaptive optics, Image quality, Image analysis, Wavefront sensors, Telescopes, Observatories, Infrared radiation, Infrared imaging, Computer simulations, Imaging systems

Read Abstract +

Proceedings Article | 28 July 2014 Paper

Paper

Characterizing instrumental effects on polarization at a Nasmyth focus using NaCo

Jozua de Boer, Julien Girard, Dimitri Mawet, Frans Snik, Christoph Keller, Julien Milli

Proceedings Volume 9147, 914787 (2014) https://doi.org/10.1117/12.2054970

KEYWORDS: Polarization, Information operations, Telescopes, Calibration, Polarimetry, Mueller matrices, Wave plates, Mirrors, Stray light, Stars

Read Abstract +

Proceedings Article | 26 September 2013 Paper

Paper

Small-angle, high-contrast exoplanet imaging with the L-band AGPM vector vortex coronagraph now offered at the VLT

Dimitri Mawet, Olivier Absil, Julien Milli, Christian Delacroix, Julien Girard, Jared O'Neal, Pierre Baudoz, Anthony Boccaletti, Pierre Bourget, Pontus Forsberg, Frederic Gonté, Serge Habraken, Mikael Karlsson, Markus Kasper, Anne-Marie Lagrange, Jean-Louis Lizon, Koraljka Muzic, Eduardo Peña, Richard Olivier, Nicolas Slusarenko, Lowell Tacconi-Garman, Jean Surdej

Proceedings Volume 8864, 88640I (2013) https://doi.org/10.1117/12.2025501

KEYWORDS: Coronagraphy, Stars, Principal component analysis, Point spread functions, L band, Adaptive optics, Exoplanets, Space telescopes, Planets, Observatories

Read Abstract +

Proceedings Article | 26 September 2013 Paper

Paper

Adaptive phase-mask coronagraph with amplitude and phase modulation for high dynamic range synchronous detection: APM2 coronagraph

P. Bourget, D. Mawet, P. Mardones, N. Schuhler, L. Pueyo, J. Girard, P. Haguenauer, F. Gonte

Proceedings Volume 8864, 88640J (2013) https://doi.org/10.1117/12.2026211

KEYWORDS: Phase shift keying, Coronagraphy, Modulation, Phase modulation, Amplitude modulation, Speckle, Avalanche photodetectors, High dynamic range imaging, Demodulation, Stars

Read Abstract +

Proceedings Article | 24 September 2012 Paper

Paper

Conceptual study for a sub-pupil instrument having 4 high order adaptive optics path for parallel multi-wavelength high contrast imaging, and medium resolution spectrometry

Frédéric Y. Gonte, Pierre Bourget, Julien Girard, Pierre Haguenauer, Dimitri Mawet

Proceedings Volume 8446, 84467Z (2012) https://doi.org/10.1117/12.927162

KEYWORDS: Adaptive optics, Coronagraphy, Image resolution, Spectroscopy, Telescopes, Sensors, Mirrors, Device simulation, Wavefront sensors, Polarization

Read Abstract +

Proceedings Article | 21 September 2012 Paper

Paper

Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

Dimitri Mawet, Laurent Pueyo, Peter Lawson, Laurent Mugnier, Wesley Traub, Anthony Boccaletti, John Trauger, Szymon Gladysz, Eugene Serabyn, Julien Milli, Ruslan Belikov, Markus Kasper, Pierre Baudoz, Bruce Macintosh, Christian Marois, Ben Oppenheimer, Harrisson Barrett, Jean-Luc Beuzit, Nicolas Devaney, Julien Girard, Olivier Guyon, John Krist, Bertrand Mennesson, David Mouillet, Naoshi Murakami, Lisa Poyneer, Dmitri Savransky, Christophe Vérinaud, James Wallace

Proceedings Volume 8442, 844204 (2012) https://doi.org/10.1117/12.927245

KEYWORDS: Coronagraphy, Space telescopes, Telescopes, Adaptive optics, Stars, Spiral phase plates, Planets, Wavefronts, Cameras, Modulation

Read Abstract +

Proceedings Article | 13 September 2012 Paper

Paper

Image quality and high contrast improvements on VLT/NACO

Julien H. Girard, Jared O'Neal, Dimitri Mawet, Markus Kasper, Gérard Zins, Benoît Neichel, Johann Kolb, Valentin Christiaens, Martin Tourneboeuf

Proceedings Volume 8447, 84470L (2012) https://doi.org/10.1117/12.925660

KEYWORDS: Adaptive optics, Calibration, Point spread functions, Stars, Coronagraphy, Image quality, Telescopes, Electroluminescent displays, Optical spheres, Imaging systems

Read Abstract +

Proceedings Article | 13 September 2012 Paper

Paper

What can be retrieved from adaptive optics real-time data?

J. Kolb, N. Muller, E. Aller-Carpentier, P. Andrade, J. Girard

Proceedings Volume 8447, 84475U (2012) https://doi.org/10.1117/12.926402

KEYWORDS: Adaptive optics, Turbulence, Point spread functions, Reconstruction algorithms, Zernike polynomials, Atmospheric modeling, Telescopes, Data modeling, Computer simulations, Instrument modeling

Read Abstract +

Proceedings Article | 13 September 2012 Paper

Paper

Extinction controlled adaptive mask coronagraph Lyot and phase mask dual concept for wide extinction area

P. Bourget, N. Schuhler, D. Mawet, P. Haguenauer, J. Girard, Frederic Gonte

Proceedings Volume 8450, 84505I (2012) https://doi.org/10.1117/12.927284

KEYWORDS: Coronagraphy, Polarization, Nulling interferometry, Phase shifts, Avalanche photodetectors, Diffraction, Phase shift keying, Liquid crystals, Mercury, Control systems

Read Abstract +

Proceedings Article | 12 September 2012 Paper

Paper

Speckle imaging observations of 2005 YU55 with the NACO-VLT no-AO mode

Sridharan Rengaswamy, Julien H. Girard, Gianluca Lombardi, Valentin Ivanov, Christophe Dumas

Proceedings Volume 8445, 84453M (2012) https://doi.org/10.1117/12.926915

KEYWORDS: Asteroids, Speckle imaging, Speckle, Observatories, Spatial resolution, Stars, Adaptive optics, Calibration, Signal to noise ratio, Telescopes

Read Abstract +

Proceedings Article | 6 October 2011 Paper

Paper

Direct imaging with a dense aperture masking in comparison with a telescope or a hypertelelescope

Fabien Patru, Jacopo Antichi, Julien Girard

Proceedings Volume 8172, 81720W (2011) https://doi.org/10.1117/12.896920

KEYWORDS: Point spread functions, Telescopes, Spatial filters, Adaptive optics, Spatial frequencies, Interferometry, Diffraction, Optical filters, Image filtering, Image resolution

Read Abstract +

Proceedings Article | 1 October 2011 Paper

Paper

The hypertelescope at work with a BIGRE integral field unit

Jacopo Antichi, Patrick Rabou, Fabien Patru, Enrico Giro, Julien Girard, Denis Mourard

Proceedings Volume 8172, 81720X (2011) https://doi.org/10.1117/12.896926

KEYWORDS: Spatial filters, Telescopes, Diffraction, Interferometry, Optical design, Optical filters, Adaptive optics, Wavefronts, Cameras, K band

Read Abstract +

Proceedings Article | 29 July 2010 Paper

Paper

Status and new operation modes of the versatile VLT/NaCo

Julien H. Girard, Markus Kasper, Sascha Quanz, Matthew Kenworthy, Sridharan Rengaswamy, Rainer Schödel, Alexandre Gallenne, Stefan Gillessen, Nicolas Huerta, Pierre Kervella, Nick Kornweibel, Rainer Lenzen, Antoine Mérand, Guillaume Montagnier, Jared O'Neal, Gérard Zins

Proceedings Volume 7736, 77362N (2010) https://doi.org/10.1117/12.856799

KEYWORDS: Adaptive optics, Stars, Point spread functions, Imaging systems, K band, Speckle, Wavefront sensors, Exoplanets, Coronagraphy, Holography

Read Abstract +

Proceedings Article | 22 July 2010 Paper

Paper

Evaluation of performance of the MACAO systems at the VLTI

Sridharan Rengaswamy, Pierre Haguenauer, Stephane Brillant, Angela Cortes, Julien Girard, Stephane Guisard, Jérôme Paufique, Andres Pino

Proceedings Volume 7734, 773436 (2010) https://doi.org/10.1117/12.857373

KEYWORDS: IRIS Consortium, Strontium, Adaptive optics, Mirrors, Stars, Deformable mirrors, Diamond, Observatories, Telescopes, Modulation

Read Abstract +

Proceedings Article | 22 July 2010 Paper

Paper

Speckle imaging with the SOAR and the very large telescopes

Sridharan Rengaswamy, Julien Girard, Guillaume Montagnier

Proceedings Volume 7734, 77341B (2010) https://doi.org/10.1117/12.857393

KEYWORDS: Speckle, Speckle imaging, Stars, Telescopes, Device simulation, Calibration, Binary data, Adaptive optics, Atmospheric modeling, Instrument modeling

Read Abstract +

Proceedings Article | 16 July 2010 Paper

Paper

An apodizing phase plate coronagraph for VLT/NACO

Matthew Kenworthy, Sascha Quanz, Michael Meyer, Markus Kasper, Rainer Lenzen, Johanan Codona, Julien Girard, Philip Hinz

Proceedings Volume 7735, 773532 (2010) https://doi.org/10.1117/12.856811

KEYWORDS: Point spread functions, Coronagraphy, Stars, Planets, Diffraction, Exoplanets, Telescopes, Cameras, Computer programming, Observatories

Read Abstract +

Proceedings Article | 17 July 2008 Paper

Paper

GUIELOA, the Mexican adaptive optics system: expected performance and operation

Julien H. V. Girard, Alan Watson, Luís Carlos Álvarez, Oscar Chapa, Salvador Cuevas, Ruben Flores, Fernando Garfias, Arturo Iriarte, Luís Artemio Martínez, Beatriz Sánchez

Proceedings Volume 7015, 701560 (2008) https://doi.org/10.1117/12.788595

KEYWORDS: Adaptive optics, Stars, Telescopes, Diffraction, Imaging systems, Charge-coupled devices, Mirrors, Optical imaging, Sensors, Atmospheric optics

Read Abstract +

Proceedings Article | 24 September 2007 Paper

Paper

The Polychromatic Laser Guide Star for tilt measurement: progress report of the demonstrator at Observatoire de Haute Provence

Renaud Foy, Pierre Éric, Jérôme Eysseric, Françoise Foy, Thierry Fusco, Julien Girard, Auguste Le Van Suu, Sandrine Perruchot, Pierre Richaud, Yoann Richaud, Xavier Rondeau, Michel Tallon, Éric Thiébaut, Michel Boër

Proceedings Volume 6691, 66910R (2007) https://doi.org/10.1117/12.733997

KEYWORDS: Telescopes, Mesosphere, Projection systems, Sodium, Laser guide stars, Adaptive optics, Photons, Algorithm development, Stars, Wavefronts

Read Abstract +

Showing 5 of 53 publications

SIGN IN TO:

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Advertisement

Advertisement