Figure 1: A color composite image in the g, r and i
bands of a small piece of the COSMOS field, as imaged by the Hyper
Suprime-Cam. This image contains thousands of galaxies as faint as 27th
magnitude. The galaxies are seen at such large distances that the light
from them has taken billions of years to reach us. The light from the
faintest galaxies was emitted when the universe was less than 10 % of
its present age. (Credit: Princeton University/HSC Project)
Figure 2: A HSC-SSP image of a massive cluster of
galaxies in the Virgo constellation showing numerous strong
gravitational lenses. The distance to the central galaxy is 5.3 billion
light years, while the lensed galaxies, apparent as the arcs around the
cluster, are much more distant. This is a composite image in the g, r,
and i band, and has a spatial resolution of about 0.6 arcsecond.
(Credit: NAOJ/HSC Project)
Figure 3: A color composite image in the g, r and i
bands of UGC 10214 known as Tadpole Galaxy in the ELAIS-N1 region. The
distance to this galaxy is about 400 million light years. The long tail
of stars made by gravitational interaction due to the galactic encounter
is characteristic. (Credit: NAOJ/HSC Project)
Figuring out the fate of the Universe is one step closer. The first
massive dataset of a "cosmic census" is released using the largest
digital camera on the Subaru Telescope. Beautiful images are available
for public at large.
The first dataset from the Hyper Suprime-Cam Subaru Strategic Program
(HSC-SSP) was released to the public on February 27th, 2017. HSC-SSP is
a large survey being done using HSC, which is an optical imaging camera
mounted at the prime focus of the Subaru Telescope. HSC has 104
scientific CCDs (for a total of 870 million pixels) and a 1.77
square-degree field of view.
The National Astronomical Observatory of Japan (NAOJ) has embarked on
the HSC-SSP survey in collaboration with the Kavli Institute for the
Physics and Mathematics of the Universe (Kavli IPMU) in Japan, the
Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in
Taiwan, and Princeton University in the United States. The project will
take 300 nights over 5-6 years. This survey consists of three layers;
Wide, Deep, and UltraDeep, using optical and near infrared wavelengths
in five broad bands (g, r, i, z, y) and four narrow-band filters.
This release includes data from the first 1.7 years (61.5 nights of
observations beginning in 2014). The observed areas covered by the Wide,
Deep, and UltraDeep layers are 108, 26, and 4 square degrees,
respectively. The limiting magnitudes, which refer to the depth (Note)
of the observations, are 26.4, 26.6 and 27.3 mag in r-band (about 620
nm wavelength), respectively, allowing observations of some of the most
distant galaxies in the universe. In the multi-band images, images are
extremely sharp, with star images only 0.6 to 0.8 arcseconds across. 1
arcsecond equals 3600th part of a degree. These high-quality data will
allow a unprecedented view into the nature and evolution of galaxies and
dark matter. This first public dataset already contains 70 million
galaxies and stars. It demonstrates that HSC-SSP is making the most of
the performance of the Subaru Telescope and HSC. In 2015, using HSC
observations over 2.3 square degrees of sky, nine clumps of dark matter,
each weighing as much a galaxy cluster were discovered from their weak
lensing signature (Miyazaki et al. 2015, ApJ 807, 22, "Properties of
Weak Lensing Clusters Detected on Hyper Suprime-Cam 2.3 Square Degree
Field"). The HSC-SSP data release covers about 50 times more sky than
was used in this study, showing the potential of these data to reveal
the statistical properties of dark matter.
Figure 4: Survey area of HSC-SSP. Blue color shows the
area of the Wide layer data included in the data release, green Deep,
and red UltraDeep, respectively. (Credit: NAOJ/HSC Project)
The total amount of data taken so far comprises 80 terabytes, which is comparable to the size of about 10 million images by a general digital camera. Since it is difficult to search such a huge dataset with standard tools, NAOJ has developed a dedicated database and interface for ease of access and use of the data.
"Since 2014, we have been observing the sky with HSC, which can
capture a wide-field image with high resolution," said Dr. Satoshi
Miyazaki, the leader of the HSC-SSP. "We believe the data release will
lead to many exciting astronomical results, from exploring the nature of
dark matter and dark energy, as well as asteroids in our own solar
system objects and galaxies in the early universe. SSP team members are
now preparing a number of scientific papers based on these data. We plan
to publish them in a special issue of the Publications of Astronomical Society of Japan.
Moreover, we hope that interested members of the public will also
access the data and enjoy the real universe imaged by the Subaru
telescope, one of the largest the world."
Funding for the HSC Project was provided in part by the following
grants: Grant-in-Aid for Scientific Research (B) JP15340065;
Grant-in-Aid for Scientific Research on Priority Areas JP18072003; and
the Funding Program for World-Leading Innovative R&D on Science and
Technology (FIRST) entitled, "Uncovering the Origin and Future of the
Universe: ultra-wide-field imaging and spectroscopy reveal the nature of
dark matter and dark energy."
Note:
"Depth" of an observation refers to how dim objects can be
studied. The light collection power of large aperture mirror (8.2 m for
the Subaru Telescope) is the crucial factor, as well as the exposure
time. For astronomical objects of the same intrinsic brightness, depth
is literally how far one can look.
Link
- HSC-SSP Public data release site
- HSC-SSP Website
- HSC Project Website
- Image of M31 Heralds the Dawn of HSC's Productivity (July 30, 2013 Subaru Tele-scope Topics)
- Hyper Suprime-Cam Ushers in a New Era of Observational Astronomy (September 12, 2012 Subaru Telescope Topics)
Source: Subaru Telescope
