KICC-led teams claim over 1,100 JWST hours in Cycle 5 General Observer program

The Kavli Institute for Cosmology, Cambridge (KICC) celebrates the outstanding success of its astronomers in the James Webb Space Telescope (JWST) Cycle 5 General Observer program. On March 13, 2026, the Space Telescope Science Institute (STScI) announced the approval of 254 proposals, allocating approximately 9,000 hours of JWST observing time for the telescope's fifth year of science operations (starting July 1, 2026). Three high-impact programs led or co-led by KICC-affiliated researchers from the University of Cambridge have been selected, securing over 1,100 hours and advancing frontier explorations of the early Universe.

These programs harness JWST's exceptional capabilities to probe the cosmic dawn, including the formation of the first galaxies, potential relics of the very first stars, and the mechanisms regulating star formation in the infant cosmos.

The three approved programmes are:

LAPIS: Large Area Parallel Imaging Survey

Program ID: 10790

Principal Investigator: Sandro Tacchella (University of Cambridge)

Time awarded: 1,000 hours (pure-parallel observations)

This programme will search for the earliest galaxies in the Universe, pushing to redshifts beyond 16 and probing cosmic times just a few hundred million years after the Big Bang. By exploiting parallel observations, it efficiently surveys large areas of sky to discover rare, extreme objects that constrain how structure first formed.

The Last Pristine Islands in the Universe – PopIII Stars Before Cosmic Noon

Program ID: 9881

Principal Investigator: Roberto Maiolino (University of Cambridge)

Time awarded: 21.3 hours (using NIRSpec/IFU)

This programme seeks direct evidence for the Universe’s first generation of stars (Population III) at later cosmic times, where detection may be more feasible. By targeting chemically pristine regions, it will test whether primordial star formation persisted longer than expected and how early chemical enrichment unfolded.

The Physical Drivers of Burstiness – A Deep Dive on LULLing Galaxies Below the Main Sequence at z > 4

Program ID: 10149

Principal Investigator: Tobias Looser (Harvard & Smithsonian Center for Astrophysics)

Co-Principal Investigator: Francesco D’Eugenio (University of Cambridge) 

Time awarded: 97.4 hours (using NIRCam/Imaging and NIRSpec/MOS)

This programme investigates why early galaxies experience cycles of intense star formation followed by quiet phases, focusing on systems that have recently “switched off” their star formation. By obtaining deep spectroscopy of galaxies below the star-forming main sequence, it will directly test whether stellar feedback or black hole activity is responsible for regulating galaxy growth in the early Universe.

These approvals highlight the leading role of Cambridge astronomers in JWST's transformative science. The programs build on KICC's expertise in high-redshift cosmology and galaxy evolution, promising groundbreaking discoveries about the Universe's formative stages. For full details on all Cycle 5 programs, visit the STScI Cycle 5 GO page here.