The Faint Source Survey (FSS) is the definitive IRAS data set for faint point sources. The FSS was produced by point-source filtering the individual detector data streams and then coadding those data streams using a trimmed-average algorithm. The resulting images, or plates, give the best estimate from the IRAS survey data of the point source flux density at every surveyed point of the sky. Moshir et al. (1992) describe the processing methods used to produce the plates and give cautionary notes about the interpretation of the images (cf. the Faint Source Catalog).
The FSS plates are in orthographic projection and in FITS format. Each field has three maps for each of the four IRAS spectral bands: a flux density map; a 1-sigma noise map; and a coverage map giving the count of detector passes.
NOTE: These images are point-source filtered and should not be used for studying extended emission. Also, a slight calibration improvement was determined after these images were produced, and the flux density and noise grids at 12, 25, 60, and 100 microns should be multiplied by 1.015, 1.008, 0.9674, and 0.9665, respectively.
Version and release date: 1.0, 1988 Dec (|beta| > 50°); 1.0, 1990 Sept (|beta| < 50°)