Scientific Motivation

The IRAS Faint Source Survey ( FSS ) contains 766,560 infrared point sources, some true, some false, the vast majority of which have no optical counterpart in the major star and galaxy catalogs such as the SAO and the UGC . Thus this potential treasure trove of infrared sources has been difficult for astronomers to utilize, requiring painstaking work with sky survey prints to find objects of potential interest. Moreover the positional uncertainties of the faintest FSS sources are sufficiently large that often several faint optical objects can be found within the error ellipse on the sky survey plates, thus complicating the identification procedure.

With the advent of large, deep, optical catalogs from digitized sky survey plates, it became possible to automate this identification process and provide the user with detailed optical identification information for all FSS sources. The four principal scientific goals of the OPTID project were:

1.

to provide a star/galaxy classification for all FSS sources and an optical (blue) magnitude, allowing users to make much more sophisticated searches through the FSS for sources of a given star/galaxy type, optical/IR color range, and optical magnitude range

2.

to provide significantly more accurate positions () than available from the IRAS positional uncertainties alone ( for the faintest FSS sources) to facilitate follow-up observations at the telescope

3.

to facilitate searches for unusual objects, such as stars with unusual IR or IR-optical colors, and faint galaxy-colored infrared sources with no optical counterpart at all

4.

to use the optical identification information to help discriminate true from false low signal-to-noise IR sources, and thus extend the usefulness of the FSS at the low signal-to-noise end.