Abstract
Abstract We present an initial analysis of the properties of an all-sky image obtained by the Far-Infrared Surveyor (FIS) onboard the AKARI satellite, at 65 μm (N60), 90 μm (WIDE-S), 140 μm (WIDE-L), and 160 μm (N160). An absolute flux calibration was determined by comparing the data with COBE/DIRBE data sets; the intensity range was as wide as from a few MJy sr−1 to > 1 GJy sr−1. The uncertainties are considered to be the standard deviations with respect to the DIRBE data, and are less than 10% for intensities above 10, 3, 25, and 26 MJy sr−1 at the N60, WIDE-S, WIDE-L, and N160 bands, respectively. The characteristics of point sources in the image were also determined by stacking maps centred on photometric standard stars. The full width at half maxima of the point spread functions (PSFs) were 63″, 78″, and 88″ at the N60, WIDE-S, and WIDE-L bands, respectively. The PSF at the N160 band was not obtained due to the sensitivity, but it is thought to be the same as that of the WIDE-L one.
Highlights
The Japanese infrared astronomical satellite AKARI (Murakami et al 2007) performed an all sky survey at six infrared bands centred at 9, 18, 65, 90, 140 and 160 μm
Since the Far-Infrared Surveyor (FIS) point spread functions (PSFs) are determined by the detector characteristics rather than optics and the PSF shapes at the WIDE-L and N160 bands are similar in pointed observations (Shirahata et al 2009), we assume that the N160 PSF is same as the WIDE-L one in the AFASS image
This paper presents an initial analysis of the imaging performance of the AKARI Far-infrared all sky survey
Summary
The Japanese infrared astronomical satellite AKARI (Murakami et al 2007) performed an all sky survey at six infrared bands centred at 9, 18, 65, 90, 140 and 160 μm. The data were pre-processed using the AKARI pipeline tool called “Green-Box” This pipeline applied basic calibrations such as corrections of non-linearity and sensitivity drifts of the detector, rejection of anomalous data due to charged particle hit (glitch), saturation, and other instrumental effects as well as dark-current subtraction. Following this initial processing, another “image” pipeline optimised for imaging large spatial scale structures was applied. Since the detector had a slow response, the detector output drifted along the scan causing some stripe patterns in the image To remove this artificial stripe pattern, we applied destriping. The final image is made with a pixel scale of 15′′
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