Prime focus spectrograph on Subaru Telescope ready for science operations

Tokyo, Japan (SPX) Jan 13, 2025
Researchers have completed the installation of a revolutionary "compound eye" instrument on the Subaru Telescope after years of meticulous effort. This cutting-edge device, known as the Prime Focus Spectrograph (PFS), incorporates approximately 2,400 prisms strategically arranged across the Subaru Telescope's expansive field of view.

This design allows simultaneous spectroscopic analysis of thousands of celestial objects, providing unparalleled insights into the formation and evolution of galaxies and the broader Universe. Among 8-meter-class telescopes, Subaru leads globally in survey capabilities, solidifying its position as a premier tool for astronomers. Scientific operations with the PFS are set to commence in February 2025.

Transforming Subaru Telescope's Capabilities

The PFS is a cornerstone of the Subaru Telescope 2.0 era, leveraging the telescope's extraordinarily wide field of view - approximately 1.3 degrees in diameter - and exceptional light-gathering ability. With 2,400 fibers positioned at the prime focus, the PFS collects light from celestial objects and simultaneously captures spectra across the visible light range and parts of the near-infrared spectrum.

Inspired by the structure of insect compound eyes, each fiber focuses on a specific direction to comprehensively cover the observation area while discerning the colors of light. This innovation significantly enhances the Subaru Telescope's efficiency for spectroscopic studies.

Collaborative Effort Spanning the Globe

The development of the PFS, spanning nearly 15 years, has been an international endeavor involving over 20 research institutions from Japan, the U.S., France, Brazil, Taiwan, Germany, and China. Spearheading this collaboration, the University of Tokyo's Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) has driven the proposal, development, and planning of large-scale sky surveys.

The National Astronomical Observatory of Japan (NAOJ) has also played a pivotal role, contributing to the instrument's development, managing project coordination, and overseeing its operational integration.

The PFS team plans an ambitious large-sky survey program spanning approximately five years, utilizing 360 nights of telescope time. This extensive survey will collect spectra from millions of distant galaxies, along with hundreds of thousands of stars in the Milky Way and the neighboring Andromeda Galaxy. The data gathered will provide critical evidence to test theoretical models on the Universe's formation and evolution.