Infrared Astronomical Satellite, IRAS
Small-Scale Structure Catalog
Structure (SSS) Catalog, also known as the catalog of "small
extended sources," contains sources resolved by the IRAS
in any band (12, 25, 60, or 100 microns) but smaller than
8' in angular extent. These non-pointlike sources are nevertheless
discrete, and this catalog complements the Point
Source Catalog, and the atlases of extended emission,
e.g., the ISSA
plates. The SSS Catalog gives the infrared characteristics
of 16,740 objects including galaxies, planetary nebulae, and
compact H II regions.
Incompleteness is a complex function of wavelength band, brightness, and location, so the absence of an entry in the SSS Catalog does not necessarily imply the lack of detectable extended emission. Many entries, mostly at 60 and 100 microns, refer only to emission features that are details in larger structures known as Galactic cirrus. Complete documentation is contained in the printed version (see reference).
While small-scale structure cannot be defined or measured with the same finality as point sources, Catalog entries always represent correlated and confirmed events in the detector output, making them valuable pointers to the IRAS images and raw data. The SSS processor has distilled from the survey a wide variety of objects and provided reasonable estimates of their parameters, but if a detailed shape description, or more accurate position, flux, or size are needed, it is necessary to go back to the fundamental reference, the raw detector output.
Version and release date: 1.0, 1985 Dec