Subaru Telescope’s New Compound Eye to Start Exploring the Universe in February

Subaru Telescope’s New Compound Eye to Start Exploring the Universe in February
Hilo, Hawai‘i – The Subaru Telescope, located on Maunakea, Hawai‘i, is excited to announce
the addition of a new capability as it studies from nearby objects to the distant Universe. A
powerful compound eye like the insect world will allow the telescope to simultaneously observe
about 2,400 celestial bodies. This innovative eye is even more potent than that of an insect; it
can capture cosmic rainbows (spectra), enabling detailed exploration of the Universe.
This remarkable instrument is called the Prime Focus Spectrograph (PFS). It features
approximately 2,400 prisms scattered across the extremely wide field of view available at the
Subaru Telescope’s primary focus, allowing for simultaneous spectroscopic observation of
thousands of celestial objects. This unrivaled capability will help researchers precisely
understand the formation and evolution of galaxies and the Universe. Among 8-meter-class
telescopes, the Subaru Telescope is the most competitive, with the largest survey capability in
the world.
PFS will be one of the flagship instruments of the “Subaru Telescope 2.0” era. Taking
advantage of the Subaru Telescope’s ultra wide field of view, approximately 1.3 degrees in
diameter at the prime focus, and world-renowned large light-gathering power, PFS will position
2,400 fibers to collect light from celestial objects and simultaneously obtain spectra across the
entire visible light range and part of the near-infrared band. Just like the compound eyes of
insects, each facet (fiber) focuses in a different direction to cover a wide area while perceiving
the colors of light from that direction. This highly ambitious instrument will dramatically enhance
the Subaru Telescope’s spectroscopic observation efficiency.
As a result of work spanning nearly 15 years with support from industrial partners around the
world, the development of PFS has been led by an international collaboration of over 20
research institutions in Japan, the U.S., France, Brazil, Taiwan, Germany, China, including
Hawai`i-based scientists, engineers, and technicians. Notably, the University of Tokyo Kavli
Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) has taken the lead
in proposing and developing the instrument as well as planning large-sky survey observations,
with the goal of testing various theoretical models about the formation of the Universe. Subaru
Telescope at the National Astronomical Observatory of Japan (NAOJ) has also played a central
role, participating in the development of the instrument and overseeing the coordination of the
project, while also being responsible for the acceptance and operation of the instrument. Many
PFS parts and modules developed and assembled in various countries were gathered on
Maunakea and installed on the Subaru Telescope. Since 2021, the international team has
conducted engineering tests and observations with the Subaru Telescope and will start scientific
operations.
Naoyuki Tamura (Professor at Subaru Telescope at NAOJ), working in Hilo, Hawai‘i, the PFS
Project Manager who has led the instrumentation, comments, “During the manufacturing,
assembly, and testing processes, I have been just continuing efforts to bring people and teams
together who are dispersed across different institutes. It is deeply moving to see it come
together as a single instrument system. However, this is just a stepping stone towards ultimate
goals such as continuing the operation for a long term, producing unprecedented scientific
outputs, and sharing exciting news from Maunakea with the local community to the fullest. The
discoveries that will be made with this cutting-edge instrument are something all of the people of
Hawai’i can be proud of; to be at the center of such a meaningful international collaboration and
human endeavor.”The PFS team plans to carry out a large-sky survey program over the next five or so years,
utilizing a total of 360 nights of telescope time. This survey will take spectra of millions of distant
galaxies, as well as hundreds of thousands of stars in the Milky Way and our neighboring
Andromeda Galaxy.
Figure 1: Example of data obtained by PFS observing celestial objects in the Andromeda
Galaxy region. On the left, the positions of the PFS fibers configured to observe individual
celestial objects are marked by circles on an image of the Andromeda Galaxy taken with HSC
(Hyper Suprime-Cam) (Credit: NAOJ). On the right, a magnified image of the observed celestial
object is shown, along with the spectra obtained by PFS(Credit: PFS Project/Kavli IPMU/NAOJ)
Figure 2: Christopher Boggess (left) and Teiji Chiba (right), the Subaru Telescope Technicians
from Hawai‘i, are installing the PFS Prime Focus Instrument at about 20-meter (more than
60-foot) height from the observation floor. (Credit: PFS Project/NAOJ)