JWST Telescope Scientist Team
The James Webb Space
Telescope (JWST) Telescope Scientist Team (TST) was convened in
2002, following a competitive NASA selection process, to provide
scientific support of the Webb Observatory development. In addition to
select functional support that has been provided by the team for the
past two decades, the team also has access to 210 hours of Guaranteed
Time Observer (GTO) time, following the end of Observatory
commissioning in mid-2022. This page provides and collects information
related to the JWST TST GTO Program, which aims to scientifically
demonstrate the telescope performance.
The JWST TST GTO Program consist of observations and supporting
theoretical investigations in three subject areas, namely:
- Transiting Exoplanet Spectroscopy
- Exoplanet and Debris Disk High-Contrast Imaging
- Local Group Proper Motion Science
A brief overview and discussion of the entire program is
available at
Information on the individual observing programs of
the JWST TST GTO Team is provided below.
Select parts of the exoplanet investigations are pursued in
collaboration with other JWST GTO Teams. The Local Group science is
pursued in collaboration with
the The
High-resolution Space Telescope Proper Motion (HSTPROMO)
collaboration. For context, a listing of the observing programs of
all JWST GTO Teams, sorted by subject area, is available at
Membership
The success of the JWST TST GTO Program relies on the skills and
contributions of a broad team of investigators with a range of levels
of seniortity. JWST data is extremely powerful and opens up entirely
new parts of observational parameter space. The GTO TST data will
provide opportunities for ground-breaking science in a supporting and
collaborative environment. Expressions of interest to join and
contribute to the work of the team are welcomed. Interested scientists
should contact one of the existing members for their specific subject
area, as identified below; existing members can make a nomination, and
advice on supporting material that may be needed. Expressions of
interest will be adjudicated subject to the team's Membership and Data
Access Policies and Procedures (available from the Member-only page).
The listing below provides the current membership of the
team. Membership exists at three levels, at the (GTO) Program
level (#), the (Science)
Subject level (&), and the (individual
research/observing) Project level (*). The team is expected to be a
continually evolving and growing entity as new members join over time.
Leads
- Matt Mountain (AURA)(#) [Telescope Scientist]
- Roeland van der
Marel (STScI)(#) [Principal Investigator (PI); Proper Motion
Science Subject Lead]
- Nikole Lewis (Cornell)(#) [Co-PI; Exoplanet Transit Spectroscopy Subject Lead]
- Marshall
Perrin (STScI)(#) [Co-PI; Deputy Telescope Scientist; High-Contrast Imaging Subject Lead]
Exoplanet Transit Spectroscopy Members
High-Contrast Imaging Members
Proper Motion Science Members
Press Releases, Images, and Media Attention
Observing Projects
Observing time allocation/division by project for Cycle 1
Transiting Exoplanet Spectroscopy
- 1353: Transit and Eclipse Spectroscopy of a Hot Jupiter(PI: Lewis; CoI list)
- 1312: Transit and Eclipse Spectroscopy of a Warm Neptune (PI: Lewis; CoI list)
- 1331: Transit Spectroscopy of TRAPPIST-1e (PI: Lewis; CoI list)
Exoplanet and Debris Disk High-Contrast Imaging
- 1411: Coronagraphy of the Debris Disk Archetype Beta Pictoris (PI: Stark; CoI list)
- 1412: Characterizing 51 Eridani Exoplanetary System (PI: Perrin; CoI list)
- 1413: MIRI coronagraphy of the Cold Substellar Companion GJ 758 B (PI: Pueyo; CoI list)
- 1414: Integral Field Spectroscopy of the Benchmark Substellar Companion HD 19467 B (PI: Perrin; CoI list)
- 1194: Characterization of the HR 8799 planetary system and planet search (PI: Beichman; CoI list) [Joint with NIRCam and MIRI GTO teams]
- 2778: Imaging Spectroscopy of the Coldest Imaged Exoplanet and a Low-Mass Accreting Protoplanet (PI: Perrin; CoI list)
Local Group Proper Motion Science
- 1304: Internal Dynamics of Milky Way Dwarf Spheroidal Galaxies (GTO; PI: van der Marel; CoI list)
- 1305: Dynamics of the Andromeda Galaxy Satellite System (GTO; PI: van der Marel; CoI list)
- 1306: Galactic Center Astrometry (GTO; PI: van der Marel; CoI list)
- 2772: Galactic Center Astrometry (2nd epoch) (GTO; PI: van der Marel; CoI list)
- 4513: Internal Dynamics of Milky Way Dwarf Spheroidal Galaxies (GTO; PI: van der Marel; CoI list)
- 4514: Dynamics of the Andromeda Galaxy Satellite System (GTO; PI: van der Marel; CoI list)
- 4515: Galactic Center Astrometry (GTO; PI: van der Marel; CoI list)
Refereed Papers
Transiting Exoplanet Spectroscopy
- JWST-TST DREAMS: Quartz Clouds in the Atmosphere of WASP-17b (Grant et al., 2023, ApJL, 956, L29)
- JWST-TST DREAMS: Non-Uniform Dayside Emission for WASP-17b from MIRI/LRS (Valentine et al., 2024, AJ, 168, 123)
- JWST-TST DREAMS: A Super-Solar Metallicity in WASP-17b's Day-side Atmosphere from NIRISS SOSS Eclipse Spectroscopy (Gressier et al., 2025, AJ, 169, 57)
- JWST-TST DREAMS: A Precise Water Abundance for Hot Jupiter WASP-17b from the NIRISS SOSS Transmission Spectrum (Louie et al., 2025, AJ, 169, 86)
- JWST-TST DREAMS: NIRSpec/PRISM
Transmission Spectroscopy of the Habitable Zone Planet TRAPPIST-1
e (Espinoza et al., 2025, ApJL, 990, L52)
- JWST-TST DREAMS: Secondary Atmosphere
Constraints for the Habitable Zone Planet TRAPPIST-1e (Glidden et
al., 2025, ApJL, 990, L53)
- JWST-TST DREAMS: Sulfur dioxide in the atmosphere of the Neptune-mass planet HAT-P-26 b from NIRSpec G395H transmission spectroscopy (Gressier et al., 2025, AJ, 170, 292)
- The Photochemical Plausibility of Warm
Exo-Titans Orbiting M-Dwarf Stars (Ranjan et al., 2025,
ApJ Letters, 993, 39)
- JWST-TST DREAMS: The Nightside Emission and Chemistry of WASP-17b (Lustig-Yaeger et al., 2025, ApJ Letters, 994, 4)
- Non-detection of Nightside Emission from HAT-P-26b due to Stellar Contamination (Sotzen et al., 2025, RNAAS, 9, 12, 352)
Exoplanet and Debris Disk High-Contrast Imaging
- JWST-TST High Contrast: Asymmetries, Dust Populations, and Hints of a Collision in the β Pictoris Disk with NIRCam and MIRI (Rebollido et al., 2024, AJ, 167, 69)
- JWST-TST High Contrast: JWST/NIRCam observations of the young giant planet β Pic b (Kammerer et al., 2024, AJ, 168, 51)
- JWST-TST High Contrast: Achieving direct spectroscopy of faint substellar companions next to bright stars with the NIRSpec IFU (Ruffio et al., 2024, AJ, 168, 73)
- JWST-TST High Contrast: Spectroscopic Characterization of the Benchmark Brown Dwarf HD 19467 B with the NIRSpec Integral Field Spectrograph (Hoch et al., 2024, AJ, 168, 187)
- JWST-TST High Contrast: Living on the Wedge, or, NIRCam Bar Coronagraphy Reveals CO2 in the HR 8799 and 51 Eri Exoplanets Atmospheres (Balmer et al., 2025, AJ, 169, 209)
- JWST-TST High Contrast:
Medium-resolution spectroscopy reveals a carbon-rich circumplanetary
disk around the young accreting exoplanet Delorme 1 AB b (Malin et al., 2025, A&A, 704, 181)
Local Group Proper Motion Science
Funding
Support for JWST GTO projects is provided by NASA through grant
80NSSC20K0586 to the JWST Telescope Scientist Team.
Last modified February 15, 2026.
Roeland van der Marel,
marel@stsci.edu.
Copyright Notice.