The {\it IRAS\/} Very Faint Source Survey Catalog \& Redshift Survey
Session 75 -- Interacting Galaxies and Starbursts
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

## [75.10] The {\it IRAS\/} Very Faint Source Survey Catalog \& Redshift Survey

M. Moshir (IPAC/Caltech/JPL), G. Aldering (OCIW \& U Minn)

Following the completion of the IRAS\/ Faint Source Survey (FSS), the data were examined for regions having high spacecraft coverage, low cirrus contamination at 60~$\mu$m and 100~$\mu$m. These regions were further narrowed down to those which had a low surface density of known nearby galaxies. This resulted in the selection of 11 IRAS\/ FSS plates with a total solid angle of 414~deg$^2$ in both the northern and southern hemispheres. These areas were re-processed through the source extraction and bandmerging pipelines at lower detection thresholds to obtain a catalog of sources with higher sensitivity than the corresponding data in the FSS. The typical 60~$\mu$m 90\% completeness level of these reprocessed data is at 110 mJy; the catalog contains many sources as faint as 70-80 mJy at 60~$\mu$m. This catalog of sources has been named the IRAS\/ Very Faint Source Survey (VFSS).

We are finishing a redshift survey of three fields from the VFSS catalog. Two fields in the south were observed on the Dupont 2.5~m at Las Campanas using both Shectman's wide-field multi-fiber system coupled to the Modular Spectrograph, and with the Modular Spectrograph in long-slit mode. A further field in the north has been observed with the Double Spectrograph on the Palomar 5~m. Redshifts have been determined for over 400 IRAS\/ VFSS galaxies down to $F_{60} = 110$~mJy. The distribution peaks at $Z \sim 0.07$ and extends to $Z \sim 0.45.$ The large-scale stucture within these fields, as well as the evolution of these IRAS\/ galaxies, is presented. This sample is especially useful for testing IRAS\/ galaxy evolution, as it samples not just ultra-luminous galaxies but more normal'' IRAS\/ galaxies out to $Z \sim 0.2$. This survey has considerable overlap in redshift range with deep optical redshift surveys. This presents an alternative to the W([OII]~3727) measure of starburst fraction with lookback time.

Two of these fields are scheduled to be observed by the MSX\/ satellite in 1995 at bands centered on $\sim$ 8, 12, 15, 22 $\mu$m at much higher spatial resolution than IRAS\/ and at the highest sensitivity attainable by MSX\/ .