STUDY OF DEEP IRAS FIELDS AT 60 jmm

A selected subset of IRAS pointed observations has been examined to study infrared galaxies at 60 /¿m in the 50 to 100 mJy range. The observations cover a total area of 20 sq° and contain a total of 746 sources with signal to instrumental noise ratios SNR >5. Detailed observations of one of these fields at visual, near-infrared, radio and x-ray wavelengths indicate that these sources, the faintest extracted from the IRAS data, are dusty galaxies much like the bulk of infrared galaxies observed by IRAS. The area covered triples, in 20 different fields, the area of the previously most sensitive IRAS survey of sources in this flux density range. The number of sources is about seven times that previously extracted, and the source density is about twice that found in the previous study at this flux level. The observed 60 /¿m source counts are consistent with an evolutionary model of the number of infrared luminous galaxies that fits the observed radio source counts; the counts are inconsistent with a nonevolutionary model. © 1995 American Astronomical Society.