Initial Results of a Comprehensive Ultrasoft Survey of the Einstein IPC Database: Source List and Confirmation of the Selection Procedure

We have carried out a survey of the entire Einstein IPC database (a total of 5934 sources) to select objects with strong components of ultrasoft X-ray emission (i.e., emission below 0.5 keV). The selection criteria are based on ratios of counts within three broad energy bands (i.e., X-ray "colors"). A total of 516 objects have been selected, with 202 (39%) having been identified through correlations with other databases. Of the currently identified objects, 45% are active galactic nuclei, 28% are stellar objects, 6% are "normal" galaxies and galaxy clusters, and the remaining 21% are "nonstellar" Galactic objects such as cataclysmic variables, pulsars, and white dwarfs. We present a discussion of the survey selection procedure, the list of selected sources, and discussions of interesting objects from the aforementioned groups. We discuss the remarkable success of our rather "low resolution" method of estimating spectral shape and present plans for follow-up studies of the as yet unidentified sources.