Subaru Telescope (NAOJ)

The Subaru Telescope is the 8.2-meter optical and infrared telescope of the National Astronomical Observatory of Japan (NAOJ), on Maunakea in Hawaii. Construction finished in 1998 and the first scientific images came in January 1999. Until the Large Binocular Telescope opened in 2005, Subaru had the world’s largest single-piece (monolithic) primary mirror. Its specialty today is width: it can image and take spectra across a large patch of sky at once, which is what cosmology surveys need.

Flagship instruments

• Hyper Suprime-Cam (HSC): a wide-field camera, first light in 2012 and open to general use since 2014.
• Prime Focus Spectrograph (PFS): about 2,400 optical fibers across a field roughly 1.3 degrees wide, so it can record thousands of spectra in one pointing. Science operations began in February 2025.

Recent results

The headline of the past two years is PFS itself. The instrument was led by Kavli IPMU and NAOJ with more than 20 institutions in Japan, the US, France, Brazil, Taiwan, Germany and China, and its arrival puts Subaru among the few telescopes that can run massive spectroscopic surveys. That is the method behind the DESI results that hint dark energy may be evolving, and it builds on the 2005 detection of the baryon acoustic peak in galaxy maps.

What to watch, 2026-2030

• 2025-2030: the PFS Subaru Strategic Program, 360 nights spread over about five years. Its data will feed work on galaxies, dark matter and dark energy, the areas Subaru’s wide-field surveys have long targeted.

Why scientists are converging here

Spectroscopic surveys are having a moment. DESI finished its planned five-year map in April 2026, and the VLT’s MOONS spectrograph saw first light in September 2026. Subaru’s wide field and thousands of fibers give the northern sky a survey engine of the same class, on a mountain shared with the Keck Observatory.