Extending to the Submillimeter Universe with the CCAT Observatory

TL;DR

Extending submillimeter cosmology, the paper presents the CCAT FYST project, a 6-meter aperture telescope at Cerro Chajnantor designed for wide-field surveys in the 100 GHz–1.5 THz range to complement Simons Observatory. The instrument centerpiece is Prime-Cam, a seven-module, >100k-KID detector camera spanning 220–850 GHz, with Mod-Cam as a testbed and CHAI as a spectroscopy option. The design emphasizes large instantaneous field of view, foreground characterization for CMB science, and line-intensity mapping of early Universe epochs (EoR) alongside studies of dusty galaxies, transients, and Galactic magnetism. Commissioning is set for 2026 with early science focusing on CMB foregrounds, clusters via SZ, and cross-survey fields with SO, enabling transformative submillimeter astronomy.

Abstract

The CCAT Observatory's Fred Young Submillimeter Telescope, a novel, high-throughput, 6-meter aperture telescope, is scheduled for first light in 2026. Located at 5600 m on Cerro Chajnantor in the Chilean Atacama Desert, the CCAT site enables unprecedented submillimeter measurement capabilities, fully overlapping with millimeter-wave surveys like the Simons Observatory. CCAT will address a suite of science goals, from Big Bang cosmology, star formation, and line-intensity mapping of cosmic reionization, to galactic magnetic fields, transients, and galaxy evolution over cosmic time. We highlight CCAT's science goals with Prime-Cam, a first generation science instrument for the Fred Young Submillimeter Telescope. Prime-Cam will field over 100,000 kinetic inductance detectors across seven instrument modules to enable over ten times faster mapping speed than previous submillimeter observatories in windows between 1.4 - 0.3 mm (220 - 850 GHz). We give an instrument summary, discuss the project status, and outline preliminary plans for early science.

Figures (3)

• Figure 1: Left: A cross-section rendering of the Fred Young Submillimeter Telescope, showing 6 m primary and secondary mirrors, and instrument, electronics, and process spaces. Prime-Cam, highlighted in red, will sit in Instrument Space 1, and be assembled using the space's crane. Right: The 5600 m elevation FYST site on Cerror Chajnantor has seen significant development, and FYST is currently under construction for first light in 2026.
• Figure 2: A timeline of the universe's evolution, highlighting Prime-Cam surveys and science goals. The CMB Survey will target CMB foregrounds, aid in the search for primordial gravitational waves to study inflation, and search for Rayleigh scattering of the CMB. The Reionization Survey will map Epoch of Reionization with C+ and CO line intensity mapping. The Dusty Galaxy Survey will trace galaxy formation through Cosmic Noon. The Galaxy Cluster Survey will study galaxy and cluster formation and the Sunayev-Zeldovich effects. The Galactic Survey will characterize our Milky Way's magnetic fields and pursue galactic polarization science. Finally, a transient search campaign will pursue submillimeter transient measurements over a wide range of time scales.
• Figure 3: Left: Prime-Cam in testing at Cornell with vacuum window blank-offs, and the planned positions of instrument modules labeled, with the first four labeled in white, and a preliminary additional three in light blue. Center: A cutaway CAD model of the Prime-Cam cryostat with instrument modules installed, showing optical elements and detector arrays. Right, top: The 280 GHz focal plane array, showing two gold-plated Si-platelet feedhorn assemblies for the Al arrays, and one Al-feedhorn assembly for the TiN arrays. Right, bottom: The 280 GHz module in testing in Mod-Cam, showing the cold readout from the back of the module through a readout harness, and the instrument module cold fingers and thermal straps connecting to the 1 K and 100 mK cold stages of the DR (not shown).