AKARI is equipped with two instruments: the FIS (Far-Infrared Surveyor) for far-infrared observations and the IRC (InfraRed Camera) for near and mid-infrared observations.
The two instruments can observe simultaneously, but they see different areas of the sky at different wavelengths and with different resolutions.
Far Infrared Surveyor (FIS):
The FIS is designed primarily to perform the All-Sky Survey in 4 photometric bands at wavelengths of 45--180 µm. The pointed observations are suitable to do photometry of point sources and/or mapping of areas from 25x10 arcmin2 to ~1 degree.
The FIS has two kinds of detector arrays: two monolithic Ge:Ga arrays for the SW-channel (45--110 µm) and a stressed Ge:Ga array for the LW-channel (110--180 µm). Both the SW and LW channels consist of two photometric bands, the narrow ones, N60 and N160, and the wide ones, WIDE-S and WIDE-L. All bands are operated simultaneously in scan mode.
The FIS detector arrays are tilted with respect to the scan direction by 26.5 deg such that the interval between the neighbouring scan paths of the detector pixels is one half of the physical pitch of the pixels. The SW and LW detector arrays observe almost the same area of the sky. The slight difference in the sky coverage is due to the difference of the projected array size.
Click here for a short overview of the FIS instrument.
Infrared Camera (IRC)
The IRC is designed to perform deep imaging observations in pointed mode, together with a survey parallel to the FIS All Sky survey, at 9 and 18 µm. Its unique wide field coverage of 10x10 arcmin2 is ideal for multi-object or extended emission observations.
|Field of View(arcmin)||9.5x10.0||9.1x10.0||10.3x10.2|
|Pixel size (arcsec)||1.46||2.34||2.51x2.39|
IRC consists of three cameras: NIR, MIR-S and MIR-L. They cover the wavelength ranges of 2--5, 5--13, 12--26 µm, respectively. Each camera is equipped with three filters and two dispersion elements.
The NIR and MIR-S cameras share the same FoV on the sky. The MIR-L camera looks at a position offset by ~20 arcmin from the other two cameras.
The dispersion elements of the IRC are set in the filter wheel so that all the light in the FoV is dispersed. A spectrum is obtained in the direction parallel to the scan path (in-scan direction). An aperture mask (slit) is provided for each camera in order to avoid contamination by nearby sources or diffuse radiation. The mask is primarily designed for extended sources. NIR camera has also an entrance for point sources.
Click here for a short overview of the IRC instrument.