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.

The C 2 Swan system (d 3 Å g -a 3 Å u ) was observed in emission for the Áv ¼ À3 to Áv ¼ þ2 sequences in the 14,000Y 24,000 cm À1 spectral range using a Fourier transform spectrometer. We carried out a global simultaneous fit by including a wide range of vibrational states. A total of 34 bands with v 0 ¼ 0Y10 and v 00 ¼ 0Y9 were rotationally assigned. Numerous discrepancies were found in the assignments and in the measured transition wavenumbers between the new measurements and previous results. Most of the measured transition wavenumbers and their assignments for relatively low-v bands agreed with published data. On the contrary, for high-v bands our line positions and assignments disagreed with the tabulated literature values. In particular, the lines of six bands involving the levels with v 0 ¼ 4, 5, and 6 are almost completely different from the previous work. Major sources of the disagreement are thought to be line congestion and perturbations found in these bands. From the analysis, perturbations for v 0 ¼ 0, 1, 2, 4, 6, 8, 9, and 10 in the d 3 Å g state were identified. A study of these rotational perturbations suggest that some of them are likely caused by interactions with high-v levels of the b 3 AE À g state.

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 µm, 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.

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