About this Article

STScI recently completed the proposal review and time allocation process for JWST Cycle 2. Although some activities are beginning to become routine, the science community is still coming up to speed on the instrument performance and therefore the science capabilities of the observatory. In recognition of the need for additional time to digest Commissioning and Early Release Science results, the Cycle 2 proposal deadline was pushed as late as possible (January 27, 2023) to still support a July 1, 2023 Cycle 2 start date. Future cycles will have a late October proposal deadline to allow more time for thorough technical reviews and long-range planning of approved programs, especially in light of NASA’s goal to minimize the time that JWST spends pointing in the Micrometeoroid Avoidance Zone (MAZ).

Proposal Submissions and Time Allocation Committee (TAC) Planning

The JWST Science Policies Group (SPG) anticipated that the Cycle 2 Call for Proposals would be popular based on the successful Commissioning and Cycle 1 Early Release Science program results. We planned the review process assuming that there would be ~1,500 proposals submitted (~25% more than submitted in response to the Cycle 1 Call.) Indeed, STScI received a record breaking 1,601 proposals! Of these, 8 proposals were disqualified for failing duplication checks or for anonymity violations. This left a total of 1,593 proposals reviewed — 1,466 in the General Observer category, 31 in the Survey category, and 104 in the Archival Research category  — requesting a total of 36,508 hours. These proposals included investigators from 46 US states (plus the US Virgin Islands and the District of Columbia), and investigators from 52 countries.

Prior to the Cycle 2 deadline, the JWST SPG developed External panels to review small proposals requesting < 15 hours of telescope time. STScI first implemented external panel review for small HST proposals (<15 orbits) in Cycle 28. External panelists do not meet to discuss proposals. Instead, they submit grades and comments asynchronously for a set of 10 – 20 proposals each in their self-identified science category. For each science category, the SPG averages the grades for each of the proposals together and uses the average grade to form a rank ordered list. Since there is no panel discussion, proposers receive comments from each of their 5 reviewers. The HST SPG has found that External panels encourage diversity, equity and inclusion in the reviewer pool and mitigate the work load for the discussion panelists.

Once the proposal deadline has passed, the JWST SPG assigns proposals to External or Discussion panelists for review, depending on science category and size. In Cycle 2, more than half of the submitted proposals fell into one of two science categories: (1) Exoplanets and Exoplanet Formation and (2) Galaxies and the Intergalactic Medium (IGM). This translated into 90 proposals for each of the three Exoplanets and three Galaxies panels. Typically, STScI requests preliminary grades from six discussion panelists; however, six reviews per proposal would have resulted in a very high workload for Exoplanets and Galaxies discussion panelists. To mitigate reviewer fatigue, we requested preliminary grades from five discussion panelists. For Cycle 3, we plan to recruit one additional Exoplanets and one additional Galaxies panel to help with the work load.

The Review Process

Selection of an annual JWST science program is an enormous community endeavor with participation from astronomers from all over the world. Thanks to everyone who participated in the review, including our excellent TAC Chair (Roberto Abraham), 14 Panel Chairs, 3 At-Large Members, 134 Discussion Panelists, 157 External Panelists, and 200 Expert reviewers (see Table 4 for the list of JWST TAC Discussion Panelists). Expert reviewers provide additional reviews for proposals that are reviewed by the Executive Committee (EC) and Joint observatory proposals.

The Cycle 2 TAC met during the last two weeks in April. The topical discussion panels met on-line April 17 – 20 to discuss and rank the larger small (15 – 25 hour), medium, archival, and survey proposals. The Executive Committee composed of the TAC Chair, Panel Chairs, and At-Large Members met in person April 24 – 26 to discuss the Large and Treasury proposals. The Panel Chairs did an outstanding job organizing the schedules for their topical discussion panels, enabling reviewers to attend to both professional and personal responsibilities during meeting days. The in-person EC meeting marked a return to in person STScI TAC meetings. The EC members appreciated the opportunity to meet in person and were even able to complete their deliberations a day early. Based on the success of the in-person Cycle 2 EC meeting, STScI has committed to holding an in person Cycle 3 EC meeting again next year.

As with most current NASA programs, all proposals were required to follow dual anonymous protocols.

The Science Program

The recommendations from the Cycle 2 TAC were presented to the STScI Director for endorsement on May 5, 2023. Table 1 summarizes the main results: 249 proposals were accepted for implementation, including 226 observing proposals, 7 survey proposals, and 16 archival research and theory programs. Some 5,000 hours were allocated with a relatively flat success rate by proposal size (Fig. 1). Approximately 32.6% of the proposals are led by PIs from ESA countries, 4.7% by PIs from Canada. Table 2 shows the overall PI distribution by country. In total, there are 2,078 unique investigators on the accepted programs. Half of the successful PIs were first-time PIs on a HST or JWST proposal. Student PIs led 10% of the successful proposals. The accepted observing programs include representation from all major observing instrumental observing modes (Table 3). Like Cycle 1, approximately 75% of the observing time on JWST will be devoted to spectroscopic programs. A full summary of the acceptance statistics is posted on the JSTUC webpage (Cycle 2 GO/AR Results)

The accepted programs span the full range of science anticipated for JWST. Figure 2 shows the proportional distribution by science category.

As with Cycle 1, several large programs address the key themes of First Light and Reionization, and Galaxy Assembly: GLIMPSE will devote ~150 hours to observe Hubble Frontiers Field cluster AS1063 using NIRCam to measure the prevalence of faint galaxies at z>6, constrain the contribution of the faintest galaxies to cosmic reionization, and probe the typical galaxy population during the Dark Ages; “Unveiling the Redshift Frontier with JWST” will spend ~135 hours conducting a deep, medium-band NIRCam imaging survey to identify galaxies with z>15 and deep coordinated parallel NIRSpec multi-object spectroscopy of 200 NIRCam-selected z>5 galaxy candidates in the GOODS-S field; “A JWST Survey of Ultraluminous Galaxies” will use NIRCam and MIRI Imaging and NIRSpec and MIRI spectroscopy of the 15 brightest ULIRGs in the local Universe to study star formation, the growth of supermassive black holes, and the effects of energetic feedback and galactic winds in galactic mergers; “The JWST Wide Area 3D Parallel Survey” and “A NIRCam Pure-Parallel Imaging Survey of Galaxies Across the Universe” will carry out pure parallel NIRISS slitless spectroscopy and pure parallel NIRCam imaging of tens of thousands of galaxies from the redshift frontier to reionization to Cosmic Noon to the modern universe.

Closer to home, the “JWST Whirlpool Galaxy Treasury” will use NIRCam and MIRI Imaging and the NIRSpec and MIRI IFUs to characterize embedded star formation on small scales (<50 pc) which, when combined with multiwavelength observations, will enable a better understanding of the global galaxy properties. Finally, three large transiting exoplanet programs were also approved. One will use NIRSpec BOTS spectroscopy during primary transit to characterize the atmospheres of short-period Jupiter-sized planets orbiting M-dwarfs to understand whether these objects are similar to giant planets orbiting Sun-like stars. Another will use MIRI Imaging in secondary eclipse to determine whether highly irradiated terrestrial exoplanets around M-dwarfs have atmospheres or are bare rocks. The final program will use NIRSpec BOTS and NIRISS SOSS spectroscopy during primary transit to search for water vapor in the atmospheres of promising water world candidates. Altogether, approximately 33% of the approved JWST Cycle 2 observations have no Exclusive Access Period. Congratulations to everyone who was awarded telescope time!

Now that the programs have been selected, the instrument branches and schedulers at STScI are working with the investigators to execute the programs in the Long-Range Plan together with the Cycle 2 Guaranteed Time Observations (~150 hours). In general, the observations will be scheduled to maximize the overall observing efficiency and to minimize the time the telescope spends pointing in the MAZ. With some 5,000 hours of GO programs now in hand, the total time allocated for science observations extends beyond 5,150 hours. The majority of the programs are expected to schedule between July 1, 2023 and June 30, 2024, although some may extend into the Cycle 3 timeframe.

JWST Cycle 3 will be here before we know it. The Cycle 3 Call for Proposals will be issued August 15, 2023, with a proposal deadline of Wednesday, October 25, 2023. With such a high oversubscription rate, there were unfortunately many excellent proposals that were not selected in Cycle 2. We hope that these proposals will be submitted in response to the Cycle 3 Call for Proposals.

Acknowledgements

We are extremely grateful to everyone who was involved in this process at any stage. It takes an enormous amount of time and energy from a huge number of people to support the review from start to finish.

We thank the JWST TAC Chair, the Panel Chairs, the At-Large members, panel members and external reviewers for the extensive efforts that they all invested in service on the Cycle 2 TAC.

In addition, numerous STScI personnel supported the review. The overall logistics were coordinated by the TAC Managers, Christine Chen and Katey Alatalo, with extensive support from Brett Blacker and Crystal Mannfolk, and from Sherita Hanna in the Events Planning Group. Among others involved were:

Administrative Support: Flory Hill, Holly Reedy (ESA), Shemiah Smith, Darlene Spencer

WASABI Support: Maria Bertch, Jeff Bucklew, Alex Framerini, Craig Hollinshead, Lauretta Nagel, Doug Paul, Joel Richon

Panel Support Staff:  Ayan Acharyya, Jonathan Aguilar, Chris Clark, Lara Cullinane, Kielan Hoch, Doug Long, Shelley Meyett, Matilde Mingozzi, Amanda Pagul, Justin Pierel, Rachel Plesha, Jenny Shih, David Stark, Eduardo Vitral, Xinfeng Xu

Levelers: Ramona Augustin, Hannah Bish, Rachel Cooper, Leo dos Santos, Malynda Chizek Frouard, Amy Jones, Logan Jones, Jens Kammerer, Darshan Kakkad, Kirsten Larson, Elena Manjavacas, Blair Porterfield, Greg Sloan, David Stark

Science Policies: Alessandra Aloisi, Andy Fruchter, Claus Leitherer, Amaya Moro Martín, Neill Reid, Jamila Pegues, Elena Sabbi, Linda Smith, Laura Watkins

Instruments & Telescope Support: Patrick Ogle, Torsten Boeker, Martha Boyer, Stacey Bright, Alicia Canipe, Paul Goudfrooij, Stephanie LaMassa, Alberto Noriega Crespo, Brian O’Sullivan, Charles Proffitt

Scheduling: Dave Adler, Beth Perriello, Tony Roman, Bill Workman

JWST Mission Office Observers: Macarena Garcia-Marin, Klaus Pontoppidan, Massimo Stiavelli

ESA Observers: Chris Evans, Paule Sonnetrucker

Facilities: Mike Venturella, Tiffany Lallo, Raven Baxter, Andre DeShazo, Gee, Bermond Few, Rob Franklin, Damon Levine

Tech Support: Thomas Marufu, Gary Gilbert and the whole ITSD team!