FR ES DE PT 日本語 中国人 중국인

Julien H Girard

astronomer

Time lapse by Dominique Joubert - 2015

I am an instrumentation physicist turned observational astronomer, currently Scientist and member of the Senior Research Staff at the Space Telescope Science Institute (STScI) in Baltimore.

I look for and study exoplanetary systems using high angular resolution and high contrast imaging techniques from space and from the ground. My collaborators and I characterize giant exoplanets, brown dwarfs and circumstellar disks with direct imaging, sometimes combined with spectroscopy and/or polarimetry. Expanding our understanding of the demographics and atmospheric composition of exoplanets gives clews on their formation and migration mechanisms.

Functionally I lead coronagraphy efforts on two NASA Astrophysics flagship missions: The James Webb Space Telescope or "JWST" (launched end of 2021) and the Nancy Grace Roman Space Telescope (to be launched at the end of 2026).

With Webb we are now starting to image more mature giant planets in the infrared in thermal emission. With the Roman Coronagraph we will hopefully image a few in visible reflected light, just like we see Jupiter in the night sky!


Views expressed here are my own, not that of STScI, AURA, NASA, ESO, ESA

About me, what I do

Université Claude Bernard Lyon-I, France   UCBL logo

PhD in Physics & Astrophysics (2005) Doctorat

On sky validation of the polychromatic laser guide star concept for adaptive optics

Advisor: Renaud Foy †

Université Grenoble Alpes, France   UGA logo

Master's in Astrophysics (2001) DEA Astrophysique et Milieux Dilués


University of Utah, USA   U of Utah logo

Master of Science in Instrumentation Physics (2000)


Université Savoie Mont Blanc, France   USMB logo

Technology Degree in Physical Measurements (1998) DUT Mesures Physiques

Post PhD positions I have held since 2006:

Space Telescope Science Institute, USA STScI logo 8 years, 7 months and counting

Scientist (Full) (June 2023 - Present) Long Term Senior Research Staff

STScI Scientist III (October 2020 - June 2023) Senior Research Staff

Support Scientist (August 2017 - October 2020) Senior Research Staff

European Southern Observatory, Chile ESO logo 8 years

Operations Staff Astronomer (August 2009 - July 2017) Paranal Adaptive Optics Specialist

Instituto Politécnico Nacional, Mexico IPN logo 10 months

Assistant Professor (October 2008 - July 2009) Profesor/Investigador Titular A at ESFM

Universidad Nacional Autónoma de Mexico (UNAM), Mexico UNAM logo 2 years

Postdoctoral Fellow (october 2006 - September 2008) Investigador Postdoctoral at IA-UNAM

Space Telescope Science Institute, USA STScI logo

JWST/NIRCam Instrument Scientist (2017 - Present) Documentation, User support

JWST/NIRCam Coronagraphy Lead (2017 - Present) Commissioning, Calibrations, Pipeline

JWST Coronagraphs Working Group / Coordination Team Lead (2017 - Present) NIRCam and MIRI

Roman Coronagraph Expert and Liaison (2017 - Present) To Science Investigation Teams (SITs), Community Participation Program (CPP), CTC and SSC

Roman Coronagraph Commissioning and Calibration Lead (2026 - Present)

European Southern Observatory, Chile ESO logo

Paranal Lead Instrument Scientist of VLT/SPHERE (2014-2017) User Support, Commissioning, Tests, Calibrations

Paranal Lead Instrument Scientist of VLT/NACO (2009-2015) User Support, (re)Commissioning, Tests, Calibrations

Adaptive Optics Group Coordinator (2009 - 2016) Commissioning, User support

UT4 Coordinator (2012-2013)

UT3 Coordinator (2014-2015)

Shift Coordinator (2013 - 2017) Lead/management of the whole VLT/VLTI/VISTA/VST operations at night and/or day.

NASA Programatic

Executive Committee of the Exoplanet Exploration Program Analysis Group (ExoPAG) (2024- Present)

Journal Referee

A&A, ApJ, AJ, JATIS, RevMex A (2008 - Present)

Funding/Grants

Chair and/or Reviewer for several NASA Panels (confidential) Exoplanets, Instrumentation
Reviewer for NSF Panels (confidendial)

Thesis Committees

PhD Defense (Reviewer): Charles Goulas at Paris Observatory, France (2025)
PhD Defense (Advisor): Blake Pantoja at Universidad de Chile, Chile (2019)
PhD Defense (Examiner): Mathias Nowak at Paris Observatory, France (2019)
PhD Defense (Advisor): Jozua de Boer at Leiden Observatory, Netherlands (2018)
PhD Defense (Reviewer): Jose Luis Aviles Urbiola at INAOE, Mexico (2010)

Telescope Time Allocation

Gemini CNTAC, National Time Allocation Committee (2014 - 2016)

At STScI

Science Personel Committee (SPC) (2024 - Present) Promotions, Renewal, transfers to the Senior Science Staff
Executive Committee (EC) of the Science Staff: Elected member (2020 - 2022)
Research Support Advisory Committee (RSAC) (2020 - 2022) Director's Discretionary Funds
Postdoc Mentoring Program (2019 - Present) Mentor of 4 Postdocs
STScI Fellowships Selection Committee (2019, 2022, 2023)
AURA Tenure Track Exoplanet Positions Conducted Interviews as Roman representative (2019)

At ESO

Instrument Review Panels (2012 - 2017) Panel member for SPHERE Paranal Acceptance Europe (PAE), ERIS Phase A, the Adaptive Optics Facility (AOF)
Observatory Reviews and one ESO Overview (2010 - 2016) Participant / Speaker

2 PhD students

Blake Pantoja (2014 - 2019), Universidad de Chile, co-advised with James Jenkins
Jos de Boer (2012 - 2018), Leiden University, co-advised with Christoph Keller Olivier Chesneau Prize for the best PhD thesis in high angular resolution astronomy

6 Master’s students

Rohan Kane (2025 - Present), Towson University

6 Bachelor’s students

2 high school students

from the Baltimore Polytechnic Institute's Ingenuity Project, a local public school advanced program in STEM.

Postgraduate Programs & Schools

Optics Laboratory (2008 - 2009) 216 hours, 9h/week, 3 classes/sessions

Instituto Politécnico Nacional / Escuela Supérior de Física y Matemáticas, Mexico IPN logo

Optics Laboratory (2008 - 2009) 216 hours, 9h/week, 3 classes/sessions

Université Claude Bernard Lyon-I, France   UCBL logo

Computer Science Principles (2003 - 2004) 64 hours

researchers can have a life too

I don't read merely enough books. I am an avid amateur of "world" music, jazz and traditional music forms from everywhere. I play, badly, the violin since age 6. I enjoy taking photographs, practicing/playing sports, hiking, cooking and eating! More than anything, I love to travel and embrace different cultures, especially with my family. Recently (and more so with covid), my wife, kids and I took up gardening and urban "mini farming". Doing stuff with my hands seems to give a nice break and breath to my mind.

Julien H. Girard at STScI in 2022

Curriculum Vitae
(PDF, Nov 2025)

Research Highlights

This is a small sample of the research results I contributed to over the years. Feel free to click on each image to open the corresponding press release. Click here for a more exhaustive list of published works and publications.

PDS 70 bc

Forming Exoplanets

PDS 70 b and c

With the extreme Adaptive Optics SPHERE instrument at the VLT we imaged (in the near-infrared) the transition disk and for the first time planet b in its large disk gap, south of the star.

Keppler+ 2018 Müller+ 2018, A&A

A year later with the integral field instrument MUSE also at the VLT we imaged (in H⍺ at 656 nm) not one but two planets in the large gap, south of the star. (Haffert et al. 2018)

Haffert+ 2019, Nature Astronomy

Girard+ 2020, SPIE

These planets are forming "in-situ", probably by gravitational instability (of the circumstellar material). Learn more with this PBS/Nova Video from an interview I gave then or click on the image to read one of the press releases.

Brown dwarf cloud bands

Luhman 16 AB (WISE 1049AB)

Using the NACO instrument at the VLT, we observed Luhman 16 AB, the closest brown dwarf pair in polarimetry mode taking advantage of the infrared wavefront sensor to close the adaptive optics loop on the two brown dwarfs themselves separated by ~1-1.5 arcsecond.

Luhman 16 AB

We detect a tiny signal of circular polarization on the A component which we interpret as the presense of cloud bands (like Jupiter's).

Millar-Blanchaer, Girard+ 2020, ApJ

Check the Caltech Press Release and Video.



or click on the image to read the press release.


HR 8799 b c d e

Giant Exoplanets with JWST/NIRCam

HR 8799 b c d e

JWST is our largest space telescope but its primary mirror only 6.5m across. Moreover when using NIRCam's coronagraphs this the Lyot stop limits that to ~5.2m. Our angular resolution is thus affected but we compensate this loss thanks to the telescope's extreme stability and sensitivity in space. Then we apply all our PSF subtraction and post-processing technique to remove the stellar glare and detect planets 10,000 to 100,000 fainter than the host star.

Balmer+ 2025, AJ

In this work we were able to detect a strong drop in the spectral energy distribution of planet e between 4.1 and 4.3 µm, the evidence of the presence of Carbone Dioxide in its atmosphere. Click on the image below to access the NASA Press Release.

HR 8799 b c d e

Girard+ 2022, SPIE is the reference publication for the first light and commissioning of the JWST/NIRCam Coronagraphy mode.

Publications

Full record

> 420 entries ADS

> 200 Refeered Papers

> 50 SPIE/Technical Papers

> 65 h-index

> 14,000 citations


Google Scholar ORCID
Download PDF

Lead author refereed

29 publications ADS

> 1,300 citations

These are refereed papers for which I consider myself a lead author (typically among the first 5 authors). I always prefer to help and provide expertise to impcatful and student-led projects than publish as first author.

First author all

23 entries

 ADS

> 90+ citations

Most Impactful refereed

100+ citations: 40 papers ADS
50+ citations: 79 papers ADS

Projects, Collaborations, Initiatives

Hover over this beautiful 30 Doradus image by JWST/NIRCam (one of my favorite) and click to open the corresponding links:

(Current projects are on top and older/past ones towards the bottom)

Roman Coronagraph

Community Participation Program (CPP)

Funded Project Team member, I contribute to calibration and commissioning programs, observation planning, simulations and community engagement

EPSIG

Extrasolar Planetary Systems Imaging Group

High Contrast Research Group at STScI. As Long Term Research Staff, I am one of the Leads.

ChEXO

CHesapeake bay area EXOplanet Meetings

1-day meeting ~once a year that brings together local exoplanet scientists. I am a SOC member.

ExoPAG

NASA Exoplanet Exploration Program Analysis Group

I am a member of the Executive Committee

Data Challenge

Roman Coronagraph Exoplanet Imaging

Between 2018 and 2021 I coordinated this challenge to get the community acquainted with Roman CGI data.

JWST ERS #1386

Early Release Science

With Program PI Sasha Hinkley and a large team we tested and validate the main high contrast modes of JWST.

LIFE

Mission Concept

A nulling interferometer in space to image exoplanets in the mid-infrared, a project led at ETH Zurich

Habitable Worlds Observatory

I endorse some science cases and I am interested in ground/space synergies for exoplanet science.

JWST TST GTO

Telescope Scientist Team (TST)

I am a High-Contrast Imaging Co-Investigator.

SPHERE Consortium / GTO

GTO Team Member (Affiliated to IPAG)

As Instrument Scientist of VLT/SPHERE, I commissioned it with the consortium and "paranalized" it.

SHARDDS survey

High-contrast imaging of Debris Disks in Young Stars

VLT/SPHERE survey of 55 main-sequence stars < 100 pc with known IR-excess debris disks (2016-2022).

ESPF Seminars @STScI

Exoplanets, Star & Planet Formation Seminars Series

From 2019 to 2023 I organized 50+ Seminars.

VORTEX Project

Liège led project to develop and observe with vector vortex phase coronagraphs

With Olivier Absil and Dimitri Mawet we installed an AGPM in VLT/NACO

VLT/NACO ISPY

GTO

Led at MPIE, Heidelberg

ExoGRAVITY

Oserve and characterize giant exoplanets

using the VLTI/GRAVITY optical interferometer (PI Sylvestre Lacour)

SpaceKLIP

Perform PSF subtraction on JWST Coronagraphic data

Post-processing package: I was one of the first users/testers during the NIRCam commissioning (Girard et al. 2022)

Giving back


As a researcher supported by public funding coming from tax payers, I find extremely important to "give back" to society through outreach, communication but also by training and supporting the next generations of scientists, by creating a safe space for everyone to feel welcome in our work environment. Let's all improve together, give eachother positive and constructive feedback!

Mentoring

Roman Coronagraph Logo

My door is open

Mentoring is one of my favorite things. I love to mentor and receive mentorship, formally and informally.

I am an institutional mentor to postdocs who ask me to, outside my fiedl of research and I am also a more "natural" mentor to early career scientists in the teams I am in.

Mental Health

Sofia

Mental health 101 on my door at STScI

In recent years it became clear (and clearer to me) that mental health issues can affect any of us, that being mindful, aware and non judegemental is really valuable in the work place. I pledge to listen and help colleagues who are in struggle.

A career in astronomy, in research, at observatorries at the interface of academia is a "marathon", is non linear and is far from easy. If I can modestly help and motivate others, I am happy to do so.

Inspiring kids

OutreachTalk

Communicating my passion at their level

Giving back through communicating and hopefully inspiring kids to pursue STEM fields or at least to like and trust Science.

This is after a series of talks I gave at one of Baltimore's public middle schools.

Reaching out

OutreachTalk

Presenting JWST to underserved communities

I've given a number of outreach talks in Mexico as I used to work there and get sollicitated. I enjoy speaking in Spanish about astronomy.

The response there is always extraordinary.

Images


Nightscape Photography



While spending nearly a thousand nights in the Atacama desert in northern Chile I picked up nightscape photography and even became the 13th ESO Photo Ambassador.

Life of an observatory scientist


What I truly love is working with creative and talented individuals who inspire me everyday. I also love to be part of big adventures and visit incredible places.

Please reach out

Space Telescope Science Institute (STScI)
3700 San Martin Drive
Baltimore, MD 21218
USA

Office 406B

jgirard@stsci.edu


If not in Baltimore, where might I be?