Calibration and Performance of the AKARI Far-Infrared Surveyor (FIS) — Slow-Scan Observation Mode for Point-Sources

We present the characterization and calibration of the Slow-Scan observation mode of the Far-Infrared Surveyor (FIS) onboard the AKARI satellite. The FIS, one of the two focal-plane instruments on AKARI, has four photometric bands between 50– 180 µm with two types of Ge:Ga array detectors. In addition to the All-Sky Survey, FIS has also taken detailed far-infrared images of selected targets by using the SlowScan mode. The sensitivity of the Slow-Scan mode is one to two orders of magnitude better than that of the All-Sky Survey, because the exposure time on a targeted source is much longer. The point spread functions (PSFs) were obtained by observing several bright point-like objects such as asteroids, stars, and galaxies. The derived full widths at the half maximum (FWHMs) are �30 ′′ for the two shorter wavelength bands and �40 ′′ for the two longer wavelength bands, being consistent with those