Dome Fuji on the Antarctic high plateau may be a good site for terahertz astronomy because of its high altitude of 3,810 m and low average temperature of −54°C. We have demonstrated that the opacity at 220 GHz from Dome Fuji in summer is very good and stable; τ = 0.045 ± 0.007. We have developed a transportable 30 cm telescope to map the Milky Way in the CO (J=4–3) and the [CI] (3P1–3P0) lines at Dome Fuji from 2014. It has a 9′ beam. Physical conditions such as density and temperature of molecular clouds could be derived from a direct comparison of CO (J=4–3) and [CI] (3P1–3P0) with CO (J=1–0) taken by the Columbia–CfA survey. We are also developing a 1.2 m sub-millimeter telescope. It will be equipped with a dual superconducting device (SIS) receiver for 500/800 GHz. The 1.2 m telescope produces a 2.2′ beam at 492 GHz and could map a molecular cloud entirely. It could also observe nearby galaxies in the CO (J=4–3), CO (J=7–6), [CI] (3P1–3P0), [CI] (3P2–3P1) and in continuum emission between 460–810 GHz.

We carried out the first seeing measurements at Dome Fuji in the 2010–2011 austral summer. From these observations, we found that the summer seeing at Dome Fuji was 1.2″ (mean), 1.1″ (median), 0.83″ (25th percentile) and 1.5″ (75th percentile), respectively. We also found that the seeing changed continuously and had a minimum around 0.7″ at ~18:00 hours daily. We compared the seeing with some weather parameters obtained from the 16 m mast, and found that the seeing had good correlations with atmosphere temperature and wind shear. These results suggest that the seeing is degraded by turbulence near the surface boundary layer. Because the data were obtained only over a short duration in summer, the general characteristics of Dome Fuji's seeing could not be evaluated. We plan to observe the seeing in winter with a stand-alone DIMM telescope. This new DIMM, which we named the Dome Fuji Differential Image Motion Monitor (DF–DIMM), will be installed at Dome Fuji in January 2013.

We present initial results from an high-resolution imaging search for damped Ly$\alpha$ absorbers toward the high-redshift quasar APM 08279+5255 by using the Adaptive Optics system (AO) attached to the Subaru telescope. We detected in total 11 objects within a $23''\times23''$ field around the quasar. Among these detected objects, we identified a possible candidate for the galaxy giving rise to the damped Ly$\alpha$ absorption at z$_{abs}$=2.974 with a criteria of distance from the sight-line toward the quasar and luminosity.

We present the outline and current status of the nano-JASMINE project. Nano-JASMINE is a nano size astrometry satellite (the total payload mass is between 1 kg and 10 kg), which is expected to be launched in 2006. The main purpose of the project is to prove and demonstrate the key technologies required for JASMINE (Japanese Astrometry Satellite Mission for Infrared Exploration) in a real space environment Gouda et. al. (2002). Nano-JASMINE will measure annual parallaxes of bright stars (7 mag) with an accuracy greater than 1 milliarcsecond after two years of operation. This is comparable to the accuracy of the Hipparcos catalog. Currently, the subject of major research and development of the project is to build optical and telescope structures using new material, and to establish a data acquisition and control system.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We have investigated the optical design for the Japan astrometry satellite mission (JASMINE). In order to accomplish measurements of astrometric parameters with high accuracy, optics with a long focal length and a wide focal plane for astrometry are required. In 1977 Korsch proposed a three mirror system with a long focal length and a wide focal plane. The Korsch system is one of the convincing models. However, the center of the field is totally vignetted because of the fold mirror. Therefore we consider an improved Korsch system in which the center of the field is not vignetted. Finally, we obtain the diffraction limited optical design with small distortion. Our project needs a common astrometric technique to obtain precise positions of star images on solid state detectors to accomplish its objectives. In order to determine the centers of stars, an image of the point source must be focused onto the CCD array with a spread of a few pixels. The distribution of photons (photoelectrons) over a set of pixels enables us to estimate positions of stars with sub-pixel accuracy. We modify the algorithm to estimate the real positions of stars from the photon weighted mean, which was originally developed by the FAME (Full-Sky Astrometric Mapping Explorer) group. Finally, we obtain the results from the experiment that the accuracy of estimation of distance between two stars has a variance of about 1/300 pixel; that is, the error for one measurement is about 1/300 pixel, which is almost an ideal result given by Poisson photon noise. We also investigate the accuracy of estimation of positions with a different size of PSF. In this case also, we find that the accuracy of estimation has a variance of about 1/300 pixel.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We made aperture masking optical interferometry experiments using up to 30 apertures and with a tip-tilt correction of wavefront error. We examined the performance of minimum redundant configurations of 11–30 sub-apertures on the pupil plane mask. These configurations have two advantages; the redundancy noise is as small as realized in non-redundant masking method, and the uv-coverage is as high as in speckle interferometry enabling to get reconstructed images without mask exchange. We also examined the effect of tip-tilt wavefront correction within a telescope pupil in front of the aperture masking optics. The light coherency between sub-apertures was shown to increase by the correction.