During an intensive commissioning run, Hyper Suprime-Cam (HSC), mounted
at prime focus on the Subaru Telescope, has successfully imaged the
Comet ISON (C/2012 S1) as it journeys toward the Sun. Especially
striking in the HSC image are the comet's long tails, which span a
distance more than twice the diameter of the full moon. (Figure 1)
Figure 1: Comet ISON (C/2012 S1) imaged by HSC, taken
during the early morning of November 5, 2013 in Hawaii in i band (760 nm
wavelength). The top of the image is to the north, and the left part is
to the east. The diameter of the frame is 1.5 degrees. Click here for a high-resolution image. (Credit: HSC Project/NAOJ).
The observation took place in the early morning of
November 5, 2013 in Hawaii during a test of non-sidereal tracking, which
follows an object that moves at a different rate than the stars. Since
Solar System objects such as comets and asteroids appear to move faster
than more distant stars and galaxies, they require this special mode of
telescope tracking, which allows observers to keep the target in view.
An additional challenge for tracking Comet ISON was its low altitude of
less than 30 degrees. Nevertheless, the commissioning team was able to
capture a clear image of the comet and its tails, including their faint
parts, which extend more than one degree away from the Sun. At the time
of the observation, Comet ISON was 170 million kilometers from the Earth
and 130 million kilometers from the Sun.
This image demonstrates some of HSC's exceptional
qualities: use of the large, light-collecting power of the Subaru
Telescope's 8.2-m primary mirror, a wide field-of-view, and sharp
imaging capability. HSC's wide field of view captures objects in an area
equivalent to the size of 9 full moons in one frame and does so with
high sensitivity. This extraordinary instrument, first installed on
August 16-17, 2012 (Hyper Suprime-Cam Ushers in a New Era of Observational Astronomy),
was the product of international collaboration among major research
partners -- the National Astronomical Observatory of Japan (NAOJ Japan),
Kavli Institute for the Physics and Mathematics of the Universe (Kavli
IPMU, Japan), the School of Science at the University of Tokyo (Japan),
KEK (High Energy Accelerator Research Organization, Japan), Academia
Sinica Institute of Astronomy and Astrophysics (ASIAA, Taiwan),
Princeton University (U.S.A) -- and with outstanding companies from
industry -- Hamamatsu Photonics K.K., Canon Inc., and Mitsubishi
Electric Corporation.
Dr. Satoshi Miyazaki, an associate professor at NAOJ
and the director of the HSC Project, conducted this commissioning run
and summarized some of the process: "In order to verify the performance
of this camera with a Solar System object as a target, we decided to
observe Comet ISON. This kind of object is tricky to track. Despite the
challenges of tracking this comet, we were very happy to see the tails
clearly shown in the image. We are delighted that we can share this
image, which proves that HSC is capable of capturing images of Solar
System objects."
Dr. Jun-ichi Watanabe, the Deputy Director General of
NAOJ and an expert on cometary research, praised this recent
achievement of the HSC team by commenting, "This image clearly shows the
power of HSC on the Subaru Telescope. The two distinct streaks of the
tails might be from their dust and the gas, respectively. I am excited
that this comet and its tail might be seen with binoculars or even with
the naked eye."
References:
- FOCAS Image of ISON
- COMICS Image of ISON
- HSC First Light Image of M31
- HSC Engineering
- HSC Project Website
- NAOJ Comet ISON Site (Only in Japanese at time of posting)
Source: Subaru Telescope
