THE ISOLWS-IRAS CROSS-CALIBRATION ON EXTRAGALACTIC SOURCES

摘要

We present a detailed comparison of the ISOLWS and IRAS 60μm and 100μm continuum fluxes for a large sample of galaxies. This sample consists of observations of galaxies taken with the LWS in the grating modes, and is unique, since the data were reduced in a uniform manner using all of the advanced data reduction techniques of LIA and ISAP. The galaxy sample is comprised of nearly all galaxies observed during the ISO mission whose far-infrared (FIR) emission fell within the 75" LWS beam and had IRAS Point Source Catalogue (PSC) detections. There were 155 such galaxies with 60μm fluxes ranging from below 1 Jy to 300 Jy. We considered the effects of pipeline (OLP) version, AOT type, and the IRAS and ISO filter shapes, as part of the comparison. A sky contribution was also identified and removed from the ISO data. The LWS data are compared between the LIA and OLP reductions. Flux comparisons were made between LWS, and IRAS 60μm and 100μm PSC results, and systematic discrepancies are examined as a function of source strength. In general, the LWS and IRAS fluxes are in good agreement. The ISO fluxes are (1) systematically lower than IRAS fluxes by 3% between 5 & 300 Jy at 60 /μm and (2) systematically higher than the IRAS fluxes by 2% between 5 & 300 Jy at 100 μm. Effects due to pipeline version, sky background, and AOT type are ruled out as the source of these differences.