A spectroscopic survey of faint compact objects

Abstract

A low-resolution spectroscopic survey is described of faint compact objects within a random subset of all compact sources in three high-latitude fields with values of bJ between 22.5 and 23.5 inclusive. Compact sources with bJ between 21 and 22.5 inclusive from a survey with higher resolution are used for comparison. A total of 117 unidentified sources are given with spectroscopic identifications for 67, and the survey is found to be sensitive to the presence of typical QSOs with strong emission features. The color-magnitude distribution of the faint Galactic stars is found to be consistent with that of models that incorporate and intermediate population-II thick disc. Red objects are absent from the survey, and very few blue objects are found. The present survey is significant in that it permits the detection of unidentified compact sources so that limits on their contributions to the source count can be established.