IRAS Point Source Catalog redshift survey

IRAS Point Source Catalog redshift survey

The IRAS Point Source Catalog redshift survey was a major astronomical program that combined the Infrared Astronomical Satellite's infrared point source catalog with optical spectroscopic redshift measurements to map the large-scale distribution of galaxies. The survey connected infrared-selected sources from the Infrared Astronomical Satellite mission with redshifts obtained at observatories such as Palomar Observatory, Kitt Peak National Observatory, and Cerro Tololo Inter-American Observatory, enabling comparisons with contemporaneous surveys like the CfA Redshift Survey and the Two-degree Field Galaxy Redshift Survey. Its outcomes influenced work by teams at institutions including the Smithsonian Astrophysical Observatory, the Max Planck Institute for Astronomy, and the Space Telescope Science Institute.

Introduction

The project began after the launch of the Infrared Astronomical Satellite in 1983, which produced the IRAS Point Source Catalog containing thousands of infrared-bright objects including galaxies, star-forming regions, and active nuclei. Motivated by the need to translate infrared flux measurements into a three-dimensional map, astronomers coordinated optical spectroscopic campaigns at facilities such as W. M. Keck Observatory and Anglo-Australian Observatory to obtain redshifts for a statistically useful subset. The resulting redshift survey provided a cross-match between the infrared-selected population and optical redshift catalogs like those produced by the Sloan Digital Sky Survey's predecessors and informed models developed at the Institute of Astronomy, Cambridge.

Survey Design and Selection Criteria

Selection prioritized sources from the IRAS Point Source Catalog with flux densities above threshold limits at 60 microns and color criteria designed to isolate extragalactic objects rather than Galactic objects such as those cataloged by IRAS teams. Target lists were assembled using positional cross-correlations with optical catalogs from the Palomar Observatory Sky Survey and the United States Naval Observatory catalogs to identify plausible galaxy counterparts. The survey adopted declination and galactic latitude cuts to match accessibility at telescopes like Palomar Observatory and Cerro Tololo Inter-American Observatory and to minimize contamination from objects listed in the IRAS Small Scale Structure Catalog. Project management and funding involved agencies such as the National Aeronautics and Space Administration and the National Science Foundation.

Observations and Data Reduction

Optical spectroscopy was obtained using multi-fiber and long-slit spectrographs at observatories including Kitt Peak National Observatory, Palomar Observatory, and Anglo-Australian Observatory. Observing runs were scheduled to complement facilities used by teams from the Smithsonian Astrophysical Observatory and the University of Cambridge. Standard data reduction pipelines employed bias subtraction, flat-fielding, wavelength calibration with arc lamps referenced to standards from the National Institute of Standards and Technology, and heliocentric velocity corrections. Redshifts were measured by cross-correlation with spectral templates developed at institutions like the European Southern Observatory and verified against emission-line identifications associated with features cataloged in atlases from the Royal Greenwich Observatory.

Catalog Contents and Data Products

The published catalog provided positions tied to reference frames maintained by the International Earth Rotation and Reference Systems Service, IRAS flux densities and quality flags from the IRAS Point Source Catalog, optical identifications cross-referenced to the Palomar Observatory Sky Survey and the USNO catalogs, and heliocentric redshifts with uncertainty estimates. Ancillary data products included spectra, finding charts, and machine-readable tables circulated through archives at the NASA/IPAC Infrared Science Archive and distributed to researchers at the Space Telescope Science Institute. The catalog entries enabled cross-matching with later datasets such as the Two Micron All Sky Survey and the Sloan Digital Sky Survey.

Scientific Results and Applications

The survey clarified the contribution of infrared-luminous galaxies to the local large-scale structure traced by earlier optical surveys like the CfA Redshift Survey and the Southern Sky Redshift Survey. Results informed studies of galaxy clustering, the infrared luminosity function, and the role of dusty star formation in environments sampled by the Hubble Space Telescope and ground-based facilities at Mauna Kea. Analyses influenced models of starburst activity in interacting systems studied in the context of research at the Max Planck Institute for Extraterrestrial Physics and comparisons with radio surveys from the Very Large Array. The catalog also provided targets for follow-up with instruments on the European Space Agency missions and for infrared spectroscopy at the Subaru Telescope.

Completeness, Biases, and Limitations

Completeness was limited by the IRAS sensitivity thresholds, the difficulty of optical identification in crowded fields near the Galactic Plane, and selection effects introduced by color cuts designed to exclude Galactic sources cataloged by the IRAS mission teams. Redshift incompleteness arose from fiber-placement constraints at facilities like the Anglo-Australian Telescope and from optically faint counterparts below limits of the Palomar Observatory Sky Survey. Systematic biases affected luminosity-function estimates and clustering measures in ways comparable to those documented for the CfA Redshift Survey and the IRAS 1.2 Jy Survey, requiring careful modeling in subsequent analyses by groups at the Institute of Astronomy, Cambridge and the Max Planck Institute for Astronomy.

Follow-up Studies and Legacy Impact

The catalog served as a legacy dataset for follow-up work linking infrared properties to star-formation rates, active galactic nucleus demographics, and environmental dependence of infrared luminosity in programs at the Space Telescope Science Institute, European Southern Observatory, and Harvard-Smithsonian Center for Astrophysics. Its cross-matched entries enabled synergy with later all-sky projects such as the Two Micron All Sky Survey, the Sloan Digital Sky Survey, and the Wide-field Infrared Survey Explorer, and informed target selection for space missions like the Spitzer Space Telescope and the Herschel Space Observatory. The survey remains an important historical bridge between early infrared sky mapping and modern multiwavelength extragalactic surveys.

Category:Astronomical catalogues