The Infrared Doppler (IRD) instrument is a fiber-fed high-resolution NIR spectrometer for the Subaru telescope covering the Y,J,H-bands simultaneously with a maximum spectral resolution of 70,000. The main purpose of IRD is a search for Earth-mass planets around nearby M-dwarfs by precise radial velocity measurements, as well as a spectroscopic characterization of exoplanet atmospheres. We report the current status of the instrument, which is undergoing commissioning at the Subaru Telescope, and the first light observation successfully done in August 2017. The general description of the instrument will be given including spectrometer optics, fiber injection system, cryogenic system, scrambler, and laser frequency comb. A large strategic survey mainly focused on late-type M-dwarfs is planned to start from 2019.
We report the current status of the Infrared Doppler (IRD) instrument for the Subaru telescope, which aims at detecting
Earth-like planets around nearby M darwfs via the radial velocity (RV) measurements. IRD is a fiber-fed, near infrared
spectrometer which enables us to obtain high-resolution spectrum (R~70000) from 0.97 to 1.75 μm. We have been
developing new technologies to achieve 1m/s RV measurement precision, including an original laser frequency comb as
an extremely stable wavelength standard in the near infrared. To achieve ultimate thermal stability, very low thermal
expansion ceramic is used for most of the optical components including the optical bench.
M. Tamura, H. Suto, J. Nishikawa, T. Kotani, B. Sato, W. Aoki, T. Usuda, T. Kurokawa, K. Kashiwagi, S. Nishiyama, Y. Ikeda, D. Hall, K. Hodapp, J. Hashimoto, J. Morino, S. Inoue, Y. Mizuno, Y. Washizaki, Y. Tanaka, S. Suzuki, J. Kwon, T. Suenaga, D. Oh, N. Narita, E. Kokubo, Y. Hayano, H. Izumiura, E. Kambe, T. Kudo, N. Kusakabe, M. Ikoma, Ya. Hori, M. Omiya, H. Genda, A. Fukui, Y. Fujii, O. Guyon, H. Harakawa, M. Hayashi, M. Hidai, T. Hirano, M. Kuzuhara, M. Machida, T. Matsuo, T. Nagata, H. Ohnuki, M. Ogihara, S. Oshino, R. Suzuki, H. Takami, N. Takato, Y. Takahashi, C. Tachinami, H. Terada
IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. It is a relatively compact (~1m size) spectrometer with a new echelle-grating and Volume-Phase Holographic gratings covering 1-2 micron wavelengths combined with an original frequency comb using optical pulse synthesizer. The spectrometer will employ a 4096x4096-pixel HgCdTe array under testing at IfA, University of Hawaii. Both the telescope/Adaptive Optics and comb beams are fed to the spectrometer via optical fibers, while the instrument is placed at the Nasmyth platform of the Subaru telescope. Expected accuracy of the Doppler-shifted velocity measurements is about 1 m s-1. Helped with the large collecting area and high image quality of the Subaru telescope, IRD can conduct systematic radial velocity surveys of nearby middle-to-late M stars aiming for down to one Earth-mass planet. Systematic observational and theoretical studies of M stars and their planets for the IRD science are also ongoing. We will report the design and preliminary development progresses of the whole and each component of IRD.
HiCIAO is a near-infrared, high contrast instrument which is specifically designed for searches and studies for
extrasolar planets and proto-planetary/debris disks on the Subaru 8.2 m telescope. A coronagraph technique
and three differential observing modes, i.e., a dual-beam simultaneous polarimetric differential imaging mode,
quad-beam simultaneous spectral differential imaging mode, and angular differential imaging mode, are used
to extract faint objects from the sea of speckle around bright stars. We describe the instrument performances
verified in the laboratory and during the commissioning period. Readout noise with a correlated double sampling
method is 15 e- using the Sidecar ASIC controller with the HAWAII-2RG detector array, and it is as low as 5 e-
with a multiple sampling method. Strehl ratio obtained by HiCIAO on the sky combined with the 188-actuator
adaptive optics system (AO188) is 0.4 and 0.7 in the H and K-band, respectively, with natural guide stars that
have R ~ 5 and under median seeing conditions. Image distortion is correctable to 7 milli-arcsec level using
the ACS data as a reference image. Examples of contrast performances in the observing modes are presented
from data obtained during the commissioning period. An observation for HR 8799 in the angular differential
imaging mode shows a clear detection of three known planets, demonstrating the high contrast capability of
AO188+HiCIAO.
The High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO), is a coronographic simultaneous differential
imager for the new 188-actuator AO system at the Subaru Telescope Nasmyth focus. It is designed primarily to search
for faint companions, brown dwarves and young giant planets around nearby stars, but will also allow observations of
disks around young stars and of emission line regions near other bright central sources. HiCIAO will work in
conjunction with the new Subaru Telescope 188-actuator adaptive optics system. It is designed as a flexible,
experimental instrument that will grow from the initial, simple coronographic system into more complex, innovative
optics as these technologies become available. The main component of HiCIAO is an infrared camera optimized for
spectral simultaneous differential imaging that uses a Teledyne 2.5 μm HAWAII-2RG detector array operated by a
Sidecar ASIC. This paper reports on the assembly, testing, and "first light" observations at the Subaru Telescope.
Direct exploration of exoplanets is one of the most exciting topics in astronomy. Our current efforts in this field are concentrated on the Subaru 8.2m telescope at Mauna Kea, Hawaii. Making use of the good observing site and the excellent image quality, the infrared coronagraph CIAO (Coronagraphic Imager with Adaptive Optics) has been used for various kinds of surveys, which is the first dedicated cold coronagraph on the 8-10m class telescopes. However, its contrast is limited by the low-order adaptive optics and a limited suppression of the halo speckle noise.
HiCIAO is a new high-contrast instrument for the Subaru telescope. HiCIAO will be used in conjunction with the new adaptive optics system (188 actuators and/or its laser guide star - AO188/LGSAO188) at the Subaru infrared Nasmyth platform. It is designed as a flexible camera comprising several modules that can be configured into different modes of operation. The main modules are the AO module with its future extreme AO capability, the warm coronagraph module, and the cold infrared camera module. HiCIAO can combine coronagraphic techniques with either polarization or spectral simultaneous differential imaging modes. The basic concept of such differential imaging is to split up the image into two or more images, and then use either different planes of polarization or different spectral filter band-passes to produce a signal that distinguishes faint objects near a bright central object from scattered halo or residual speckles.
In this contribution, we will outline the HiCIAO instrument, its science, and performance simulations. The optical and mechanical details are described by Hodapp et al. (2006)1. We also present a roadmap of Japanese facilities and future plans, including ASTRO-F (AKARI), SPICA, and JTPF, for extrasolar planet explorations.
Subaru Telescope has currently achieved the following performances. 1. Image Quality. (1) Subaru Telescope delivers a median image size, evaluated by equipped Auto Guider (AG) cameras, of 0.6-0.7 arcsec FWHM in the R and I-band at all the four foci: Prime (P), Cassegrain (Cs), and tow Nasmyth (Ns). (2) The best image sizes obtained so far are 0.2 arcsecs FWHM without AO in near-infrared (IR), less than 0.1 arcsec FWHM with AO, and 0.3 arcsec FWHM in optical and mid-IR wavelengths. (3) Stable Shack-Hartmann measurement enables one to keep the errors of Zernike coefficients to less than 0.2μm which corresponds to ~0.1 arcsec image size. 2. Tracking and Pointing. (1) Blind pointing accuracy is better than 1 arcsec RMS over most of the sky. (2) Tracking accuracy is better than 0.2 arcsec RMS in 10 minutes. (3) Guiding accuracy is between 0.8 and 0.18 arcsec RMS with 12-18th magnitude guide stars. 3. IR secondary mirror (M2). (1) Chopping performances: typical figures are at 3 Hz, 80% duty cycle with 30-60 arcsec chopping throw. (2) Tip-Tilt performances: Position stability is about 0.030 arcsec RMS for the effective closed-loop bandwidth less than 5 Hz. 4. Others. (1) The reflectivity of the primary mirror has been maintained at higher than 85 and 95% at 670 and 1300 nm wavelengths by regular cleaning with CO2 ice every two to three weeks. (2) The reflectivity of the blue-side image rotator (ImR) at Nasmyth-optical focus was improved after re-coating of mirrors.
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