Subaru adaptive optics is a system of curvature wavefront sensor
coupled with bimorph type deformable mirror. The number of element for each component is 36. The system is attached on the Cassegrain focus of the telescope. The open-use observation of the AO system has been started from April of 2002. In this paper, we report experiences obtained from Subaru adaptive optics system for two years of open-use operation. These experiences will be of value for development of
future AO systems.
A search for extrasolar planets using the ESO VLTI PRIMA facility
will become feasible in 2007. An astrometric accuracy of 10 micro-arcseconds will allow us to detect sub-Uranus mass planets around the
most nearby stars, as well as to conduct a planet search around stars of different ages. Most of the PRIMA hardware subsystems are currently being developed by industry. At the same time a scientific Consortium has formed that will deliver the differential delay lines and astrometric software for PRIMA to ESO.
In this paper we describe the planned efforts by the Consortium
related to the "PRIMA astrometry operations and software". These
activities include an overall "PRIMA astrometry error budget", a
"PRIMA astrometry calibration and observation strategy", the "PRIMA astrometry observation preparation tools" and the "PRIMA astrometry data reduction tools". We describe how all these components fit together in an overall approach to the flow of knowledge within the project. First by quantifying the fundamental limits of the VLTI infrastructure and the astronomical sources under study. Followed by elimination or suppression of the errors through either a hardware change to the system, software control of the system, or a proper calibration and observation strategy.
The ultimate goal is being able to calibrate all PRIMA astrometric data acquired over the full lifetime of PRIMA (5 to 10 years) to a uniform accuracy of 10 micro-arcseconds. This will allow identification of long-term trends in the astrometric parameters due to planetary companions around nearby stars and to determine the distances and proper motions for the selected sources.
The PRIMA facility will implement dual-star astrometry at the VLTI. We have formed a consortium that will build the PRIMA differential delay lines, develop an astrometric operation and calibration plan, and deliver astrometric data reduction software. This will enable astrometric planet surveys with a target precision of 10μas. Our scientific goals include determining orbital inclinations and masses for planets already known from radial-velocity surveys, searches for planets around stars that are not amenable to high-precision radial-velocity observations, and a search for large rocky planets around
nearby low-mass stars.
Amplitude apodization of a telescope's pupil can be used to reduce the diffraction rings (Airy rings) in the PSF to allow high contrast imaging. Rather than achieving this apodization by selectively removing light at the edges of the pupil, we propose to produce the desired apodized pupil by redistributing the pupil's light. This lossless apodization concept can yield a high contrast PSF which allows the efficient detection of Earth-sized planets around stars at ~10pc with a 2m visible telescope in space. We review the current status of a JPL-funded study of this concept for the Terrestrial Planet Finder (TPF) mission, including a lab experiment and extensive computer simulations.
We introduce a near-infrared camera named coronagraph imager with adaptive optics (CIAO) mounted on the Subaru 8m telescope. Combined with the Subaru 36 elements adaptive optics (AO), CIAO can produce nearly diffraction limited image with approximately 0.07 arcsec FWHM at K band and high dynamic range imaging with approximately 10 mag difference at 1 arcsec separation under typical seeing conditions. We have carried out performance tests of imaging without and with coronagraph mask since its first light observation held on 2000 February. Because of limited weather conditions, the performance under best seeing conditions has not been tested yet. At a typical natural seeing condition of 0.4 - 0.8 arcsec, halo component of PSF using 0.2 - 0.8 arcsec mask can be reduced up to 70% comparing with that without mask using AO. Even after correction, residual wave front error has typically 1.2 rad2 which corresponds to the Strehl ratio of approximately 0.3 at K band. Such wave front errors degrades the image quality; this is a common problem of coronagraph on the ground-based telescope with non high-order AO. Nevertheless we emphasize that there are various advantages on our coronagraph: the clean PSF of CIAO, reduction of readout noise, and less effect of detector memory problem. Compared with coronagraphs on smaller telescopes, the PSF shape is sharper and it brings higher detectability of sources around bright objects.
We report the development and performance of a near-IR polarimeter for the Subaru 8.2m telescope. The polarimeter is currently used with one of the Subaru instruments, CIAO, the stellar coronagraphic imager with adaptive optics. CIAO is the instrument specialized to obtain high contrast images of faint objects in the vicinity of bright objects. For achieving both high spatial resolution and high dynamic range, the instrument is used wiht the Subaru adaptive optics and has a dedicated cold coronagraphic capability. The polarimeter comprises two components. One component consists of an achromatic half-waveplate, an achromatic quarter-waveplate, and a calibration wire grid. Both half- and quarter-waveplates are rotatable and retractable, while the calibrator is only retractable. This componetn is placed upstream of any opticla components including adaptive optics system, which minimizes the effect of various mirros on instrumental polarization. The other component consists of two anlayzers, a cold wire grid and acold Wollastron prism. These are placed in the filter wheels of CIAO cryostat and can be chosen. The whole system is remotely controlled.
We have carried out KHL band high resolution imaging and H band imaging-polarimetry of the Red Rectangle nebula using CIAO and 36 element AO mounted on the 8.2m Subaru telescope. HK band images show a X-shape structure close to 0.1 inch and 2 lobes with separation of 0.15 inch at the north and the south. Our L band image show a small clump and its position is 0.1 arcsec east from the center of the southern lobe. The polarization map shows roughly centrosymmetric vector pattern and the center of the pattern is consistent with that of 2 lobes. There is scatter of the vector pattern at approximately 0.1 inch east from the southern lobe and a local minimum in the degree of polarization. These results can explain that the primary star HD44179 is at 0.1 inch east from the southern lobes and the dominant illumination source is a M type star at the center of the nebula.
We describe a near-IR coronagraphic camera built for use with the Subaru 8.2-m telescope and its adaptive optics system. The purpose of this instrument CIAO is to obtain high-resolution images of faint objects in close vicinity of bright objects at IR wavelengths. Such a desire is strong in astronomy, especially in the study of companion brown dwarfs and extra-solar planets, circumstellar disks around both young stellar objects and main-sequence stars, jets and outflows form both young stellar objects and main-sequence stars, jets and outflows from both young stars and evolved stars, circumnuclear regions around AGNs, and host galaxies of QSOs. CIAO is a 1-5 micron camera with tow focal plate scales: 22 milli-arcsec/pixel and 11 milli-arcsec/pixel. The camera is equipped with the standard broad-band filters as well as a number of narrow-band filters. Choice of masks, filters and camera lenses and optical alignment with collimator and detector are made with cryogenic motors. CIAO utilizes one ALLADIN II 'science'-grade detector array manufactured by SBRC. Occulting masks whose diameter ranges from 0.1 to 3 arcsec and several types of pupil masks are selectable, all cooled down to about 60 K and the detector is cooled to about 30 K. Also available are a R <EQ 1000 grism with coronagraphic slits and a polarimetric module. We also present preliminary results from the first commissioning run at the Subaru telescope.
The scientific objectives, design concept, and expected performance of a coronagraphic spectrometer that is planned for installation as a spectrographic mode of the coronagraphic imager with adaptive optics (CIAO) for the 8 m Subaru telescope are described.
The infrared instrumentation plan for the Subaru telescope is described. Four approved infrared instruments and one test observation system are now in the construction phase. They are coronagraph imager using adaptive optics (CIAO), cooled mid- infrared camera and spectrograph (COMICS), infrared camera and spectrograph (IRCS), OH-airglow suppressor spectrograph (OHS) and mid-infrared test observation system (MIRTOS). Their performance goals and construction schedules are summarized. The plan for procurement and evaluation of infrared arrays required by these instruments is briefly described.