National Astronomical Observatory of Japan
February 22, 2006
MOIRCS -- Subaru's new "infrared eye" now open
Subaru Telescope opened its doors to astronomers from all over the world
in December, 2000. In the five years since then, the telescope's
capabilities have been further advanced through ongoing development of
new observational instruments. Leading the charge, we now have MOIRCS,
the Multi-Object Infrared Camera and Spectrograph which became available
for general use in February, 2006.
The Widest Field of View for Infrared Imaging and Spectroscopy
Co-developed by Tohoku University and the National Astronomical
Observatory of Japan (NAOJ), MOIRCS has two giant four-million pixel
detectors. With a field of view of 4 arcmin x 7 arcmin (Note 1), MOIRCS
has the widest view of all the infrared instruments on the world's 8 to
10 meter caliber telescopes. This field of view is 8.6 times wider than
that of CISCO, our Cooled Infrared Spectrograph and Camera. In
conjunction with a large primary mirror, such as that of Subaru, a wide
field of view is key to the exploration of objects at the far reaches of
MOIRCS' First Light Images
Figure 2 was taken in 2004, in conjunction with the first engineering
test of the instrument. The entire Orion Nebula (Messier 42) fit in just
two MOIRCS images. It would require as many as 17 shots to capture an
image like this with the narrow field of view of CISCO. Compare the
image taken with MOIRCS to a composite of 9 images taken with CISCO in
the Image of Orion Nebula (Subaru First Light Image: January, 1999).
This really gives you a feel for the size of the MOIRCS field of view.
Figure 3 is an image of the center of our Galaxy. The many stars in our
Galaxy and nearby dark clouds create a complex and memorable mix of
light and dark. Infrared light is able to penetrate dark clouds better
than optical light. MOIRCS is thus able to image stars right into the
Galaxy's center. If you compare an optical and infrared image of the
Galactic Center, you can see that many stars do not show up in the
optical image. (A comparison of optical and infrared images of the
Powerful Infrared Multi-Object Spectrograph
Not only does MOIRCS have a wonderfully large field of view, it also has
the capability to obtain multiple spectra of astronomical objects at the
same time (Note 2). MOIRCS is the first instrument to provide this
capability in the infrared for an 8 to 10 meter class telescope. Earlier
infrared spectrographic instruments such as IRCS and OHS are only able
to analyze the light from one celestial object at a time. MOIRCS
dramatically increases observation efficiency with the ability to
perform spectroscopy with light coming from many objects at the same time.
Overcoming Design Challenges
Anything warm, including an observational instrument, emits light in the
infrared. To observe infrared light coming from celestial objects, the
interior of the instrument must be cooled to minus 150 degrees or below,
including the mask that selects light from objects of interest for any
specific observation. (Note 3) For MOIRCS to be successful, the design
team had to overcome several challenges, such as developing a drive
mechanism for the mask which could withstand cryogenic conditions.
Fortunately, the team was able to overcome all the design challenges and
MOIRCS's spectroscopy function worked flawlessly during its first
observational test in January, 2005. Since then performance testing is
ongoing and preparations for opening for general use in August, 2006 are
This multi object spectroscopy original data is from a single
observation with MOIRCS (H+K band). Each barcode-like strip of light in
the left and right side of this image is the spectrum of an individual
object. This image shows the spectra of 31 different objects, one of the
largest numbers of infrared spectra in a single observation. The
barcode-like pattern is actually the spectrum of Earths atmosphere. The
spectrum of the astronomical object is the faint line of light running
horizontally through the middle of the barcode pattern. The thick,
bright, continuous lines that run across either the left or right side
of the image are from holes in the mask for aligning the mask with the
position of stars. (Click here for a diagram of the Multi Object
Built by Graduate Students
Graduate students from Tohoku University were the main work force on the
MOICS development team. The students moved from Japan to Hawaii and
worked with Subaru Telescope staff for over five years. Ryuji Suzuki,
the graduate student who has been involved the longest, explains, "The
development of a large instrument like MOIRCS includes a great many
different tasks, so it was very important for each individual involved
to take full responsibility for performing their part of the work. "Dr.
Takashi Ichikawa, associate professor of Tohoku University who oversaw
the graduate students while directing the development reflects, "The
fact that they could go from having zero expertise to this great
achievement has led me to raise my expectations for the potential and
capabilities of young researchers."
A Handcrafted Instrument
Many astronomical instruments are special ordered from manufacturers.
MOIRCS, however, was built up part by part from individually procured
high performance parts, each carefully tested as the team built the
instrument. Koji Omata, MOIRCS project manager at Subaru Telescope,
explains, "the significance of MOIRCS's development is that we set a
precedent for instrument development at observatories -- our challenge
was to carry out the project "Quickly" (i.e. on a deadline), "Cheaply"
(i.e. on a budget) and "Well" (i.e. with high performance). I expect
that much of the difficulties we overcame and the experience we gained
will prove highly valuable to future instrument development."
A Dream Come True
As the universe expands, all the visible light emitted by the galaxy
shifts to the infrared region (red shift). Therefore, to study the
current frontier of the distant universe, large-scale telescopes have
awaited the development of multi-object infrared spectroscopic
instruments. Tadayuki Kodama, an associate professor at NAOJ and one of
the first users of MOIRCS, says, "with this revolutionary instrument, we
are going to be able to study the properties of stars in galaxies that
existed when the Universe was only one tenth of its current age. I'm
really excited that we can now study the formation and evolution of
galaxies beginning at such early times."
Since it saw First Light back in September year before last, MOIRCS has
had over a year of continued efficiency upgrades and improvements. What
view into the Universe will be unveiled with this new "infrared eye"
that so dramatically increases the capabilities of the Subaru telescope?
Look for more MOIRCS news to find out.
Note 1: 1arcminute equals one sixtieth of one degree.
Note 2: Spectroscopy is the process of resolving light all wavelengths
of light coming from a celestial object and analyzing in detail the
physical properties of that object.
Note 3: Click here for more about the multi-object spectroscopic
observation of FOCAS, the Faint Object Camera And Spectrograph for
visible light observation, and the mask.
For further information on MOIRCS, please go to the Subaru Telescope
MOIRCS Page, or to the MOIRCS Group Page.
MOIRCS Group: Director: Takashi Ichikawa (Astronomical Institute, Tohoku
University); Previous Director: Testuo Nishimura (Subaru Telescope,
National Astronomical Observatory of Japan); Project Manager: Koji Omata
(Subaru Telescope, National Astronomical Observatory of Japan);
Development Members (in alphabetical order): Yuka Katsuno (Subaru
Telescope, National Astronomical Observatory of Japan); Masahiro Konishi
(Tohoku University); Ryuji Suzuki / Ichi Tanaka / Chihiro Tokoku (Subaru
Telescope, National Astronomical Observatory of Japan), Toru Yamada
(Mitaka Campus, National Astronomical Observatory of Japan),
TomohiroYoshikawa (Tohoku University).
Direct inquiries to: Takashi Ichikawa at <ichikawa at astr.tohoku.ac.jp>
[NOTE: Images and weblinks supporting this release are available at