AKARI FAR-INFRARED ALL SKY SURVEY

We demonstrate the capability of AKARI for mapping diffuse far-infrared emission and achieved reliability of all-sky diffuse map. We have conducted an all-sky survey for more than 94% of the whole sky during the cold phase of AKARI observations in 2006 Feb. -2007 Aug. The survey in the far-infrared waveband covers 50 mu m - 180 mu m with four bands centered at 65 mu m, 90 mu m, 140 mu m, and 160 mu m and spatial resolution of 30 '' - 40 '' (FWHM). This survey has allowed us to make a revolutionary improvement compared to the IRAS survey that was conducted in 1983 in both spatial resolution and sensitivity after more than a quarter of a century. Additionally, it will provide us the first all-sky survey data with high-spatial resolution beyond 100 mu m. Considering the extreme importance of the AKARI far-infrared diffuse emission map, we are now investigating carefully the quality of the data for possible release of the archival data. Critical subjects in making an image of diffuse emission from the detected signal are the transient response and the long-term stability of the far-infrared detectors. Quantitative evaluation of these characteristics is the key to achieve sensitivity comparable to or better than that for point sources (< 20 - 95 [MJy/sr]). We describe current activities and progress that are focused on making high quality all-sky survey images of the diffuse far-infrared emission.