The Far-Infrared Surveyor (FIS) for AKARI

The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and uses two kinds of array detectors. The FIS arrays and optics are designed to sweep the sky with high spatial resolution and redundancy. The actual scan width is more than eight arcmin, and the pixel pitch is matches the diffraction limit of the telescope. Derived point spread functions (PSFs) from observations of asteroids are similar to the optical model. Significant excesses, however, are clearly seen around tails of the PSFs, whose contributions are about 30% of the total power. All FIS functions are operating well in orbit, and its performance meets the laboratory characterizations, except for the two longer wavelength bands, which are not performing as well as characterized. Furthermore, the FIS has a spectroscopic capability using a Fourier transform spectrometer (FTS). Because the FTS takes advantage of the optics and detectors of the photometer, it can simultaneously make a spectral map. This paper summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japa

Far-infrared detection limits - I. Sky confusion due to Galactic cirrus

Fluctuations in the brightness of the background radiation can lead to confusion with real point sources. This type of confusion with background emission is relevant when making infrared (IR) observations with relatively large beam sizes, since the amount of fluctuation tends to increase with the angular scale. To quantitively assess the effect of the background emission on the detection of point sources for current and future far-IR observations by space-borne missions such as Spitzer, ASTRO-F, Herschel and Space Infrared Telescope for Cosmology and Astrophysics (SPICA), we have extended the Galactic emission map to a higher level of angular resolution than that of the currently available data. Using this high-resolution map, we estimate the sky confusion noise owing to the emission from interstellar dust clouds or cirrus, based on fluctuation analysis and detailed photometry over realistically simulated images. We find that the confusion noise derived by simple fluctuation analysis agrees well with the results from realistic simulations. Although sky confusion noise becomes dominant in long wavelength bands (> 100 mum) with 60-90 cm aperture missions, it is expected to be two orders of magnitude lower for the next generation of space missions (with larger aperture sizes) such as Herschel and SPICA

Auxiliary partial orthotopic living donor liver transplantation in a patient with alcoholic liver cirrhosis to overcome donor steatosis

The efficacy of auxiliary partial orthotopic liver transplantation (APOLT) to overcome the problems associated with a markedly steatotic graft in a living donor has not been fully explored. We have recently performed APOLT in a patient with alcoholic liver disease, where the only potential candidate donor was affected by 50% macrovesicular steatosis and 30% microvesicular steatosis. The recipient's left liver was resected and the donor's left liver, corresponding to a 0.46% graft-to-recipient weight ratio, was orthotopically transplanted. The postoperative course of this patient was uneventful, except for a transient large amount of ascites. Native liver volume in the recipient serially decreased, and the volume of the graft serially increased after transplantation. Four months after transplantation, the donor and recipient are doing well with a normal liver function. In conclusion, APOLT may be a feasible solution for a markedly steatotic living donor graft in patients with alcoholic liver disease

The infrared astronomical mission AKARI

AKARI, the first Japanese satellite dedicated to infrared astronomy, was launched on 2006 February 21, and started observations in May of the same year. AKARI has a 68.5 cm cooled telescope, together with two focal-plane instruments, which survey the sky in six wavelength bands from mid- to far-infrared. The instruments also have a capability for imaging and spectroscopy in the wavelength range 2-180 mu m in the pointed observation mode, occasionally inserted into a continuous survey operation. The in-orbit cryogen lifetime is expected to be one and a half years. The All-Sky Survey will cover more than 90% of the whole sky with a higher spatial resolution and a wider wavelength coverage than that of the previous IRAS all-sky survey. Point-source catalogues of the All-Sky Survey will be released to the astronomical community. Pointed observations will be used for deep surveys of selected sky areas and systematic observations of important astronomical targets. These will become an additional future heritage of this mission