Mitsunobu Kawada
The Institute of Space and Astronautical Science (ISAS),
3-1-1 Yoshino-dai, Sagamihara, Kanagawa 229-8510, Japan
The Far-Infrared Surveyor (FIS) is one of the two focal plane instruments of the Infrared Imaging Surveyor, IRIS, which is a Japanese infrared astronomical satellite. FIS is designed primarily to perform an all-sky survey with several photometric bands like IRAS (the Infrared Astronomical Satellite). Advantages of FIS to IRAS are its high detectivity of point sources and its longer wavelength capability. These features are gained by remarkable improvement in detector technology. FIS adopts currently developed unstressed and stressed Ge:Ga array detectors to cover 50 to 200 µm in wavelength. Due to highly sensitive detector system, it is expected to detect over 10 million objects by the all-sky survey, including a lot of high-z objects (>10000 objects at z>1).
FIS also has spectroscopic capability by a Fourier spectrometer covering 50 to 200 µm in wavenumber with spectral resolution of 0.5 cm-1. The same detector arrays of the scanner are used and these two functions are switched. As a result of combining a spectroscopic function with the scanner, FIS becomes an unique instrument. The basic observation mode of the FIS is an all-sky survey using the scanner. The spectroscopic function is operated in the pointing mode in which it can take longer integration time (up to 500 sec). Spectral information can be used to estimate the redshifts of strange objects detected by the all-sky survey. The spectrometer is also a powerful instrument to reveal the physical properties of galactic and nearby sources.
keywords: Astronomical Satellite, IR Survey, Fourier Spectrometer
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