Optical Identification of Sources in the IRAS Faint Source Database

Abstract

The need to establish the optical counterparts of the sources in any major non-optical sky survey is self evident. When the original IRAS Point Source Catalogue (PSC) was published, only about 28% of the ∼ 250 000 sources had positional associations with objects in astronomical catalogues. Although these associations are not equivalent to identifications, in the case of IRAS sources with optically bright counterparts the two are in general synonymous. Nevertheless, despite the extensive study of IRAS sources both with and without associations over the past 8 years, it is clear that the optical counterparts are unknown for more than half of the PSC sources. With the availability of the IRAS Faint Source Database, which contains ∼ 750 000 sources (including the PSC) down to a considerably fainter limit, the need for a systematic identification program is even more clear-cut if the potential of the IRAS mission is to be fully realised. Furthermore, the launch of the non-survey ISO mission in 1993 adds to the urgency of this program.