IRAS flux densities, redshifts, and infrared luminosities are reported for all sources identified in the IRAS Revised Bright Galaxy Sample (RBGS), a complete flux-limited survey of all extragalactic objects with total 60 lm flux density greater than 5.24 Jy, covering the entire sky surveyed by IRAS at Galactic latitudes |b| > 5 . The RBGS includes 629 objects, with median and mean sample redshifts of 0.0082 and 0.0126, respectively, and a maximum redshift of 0.0876. The RBGS supersedes the previous two-part IRAS Bright Galaxy Samples (BGS 1 +BGS 2 ), which were compiled before the final (Pass 3) calibration of the IRAS Level 1 Archive in 1990 May. The RBGS also makes use of more accurate and consistent automated methods to measure the flux of objects with extended emission. The RBGS contains 39 objects that were not present in the BGS 1 +BGS 2 , and 28 objects from the BGS 1 +BGS 2 have been dropped from RBGS because their revised 60 lm flux densities are not greater than 5.24 Jy. Comparison of revised flux measurements for sources in both surveys shows that most flux differences are in the range $5%-25%, although some faint sources at 12 and 25 lm differ by as much as a factor of 2. Basic properties of the RBGS sources are summarized, including estimated total infrared luminosities, as well as updates to cross identifications with sources from optical galaxy catalogs established using the NASA/IPAC Extragalactic Database. In addition, an atlas of images from the Digitized Sky Survey with overlays of the IRAS position uncertainty ellipse and annotated scale bars is provided for ease in visualizing the optical morphology in context with the angular and metric size of each object. The revised bolometric infrared luminosity function, (L ir ), for infrared-bright galaxies in the local universe remains best fit by a double power law, (L) / L , with = À0.6(AE0.1) and = À2.2(AE0.1) below and above the '' characteristic '' infrared luminosity L Ã ir $ 10 10:5 L , respectively. A companion paper provides IRAS High Resolution (HIRES) processing of over 100 RBGS sources where improved spatial resolution often provides better IRAS source positions or allows for deconvolution of close galaxy pairs.

This paper discusses the optical spectroscopic properties of the IRAS 1-Jy sample (f 60 > 1 Jy) of ultraluminous infrared galaxies (ULIGs: L ir > 10 12 L ⊙ ; H o = 75 km s −1 Mpc −1 and q o = 0). One hundred and eight of the 118 1-Jy ULIGs have been observed at ∆λ = 8.3Å resolution over the wavelength range ∼ 4500Å -8900Å. These data are combined with large, previously published sets of optical spectroscopic data of lower luminosity infrared galaxies to look for systematic trends with infrared luminosity over the luminosity range L ir ≈ 10 10.5 − 10 13 L ⊙ . As found in previous studies, the fraction of Seyfert galaxies among luminous infrared galaxies increases abruptly above L ir ≈ 10 12.3 L ⊙ -about 50 % of the galaxies with L ir > 10 12.3 L ⊙ present Seyfert characteristics. Many of the optical and infrared spectroscopic properties of the Seyfert galaxies are consistent with the presence of a genuine active galactic nucleus (AGN). About 30 % of these galaxies are Seyfert 1s with broad-line regions similar to those of optical quasars. Published near-infrared spectroscopy also suggests that many of the Seyfert 2 galaxies (especially those with warm IRAS 25-to-60 µm colors) are in fact obscured Seyfert 1 galaxies with broad ( ∼ > 2,000 km s −1 ) recombination lines at 2 µm, where dust obscuration is less important. The percentage of Seyfert 1 ULIGs increases with infrared luminosity, contrary to the predictions of the standard unification model for Seyfert galaxies. Comparisons of the broad-line luminosities of optical and obscured Seyfert 1 ULIGs with those of optically selected quasars of comparable bolometric luminosity suggest that the dominant energy source in most of these ULIGs is the same as in optical quasars, namely mass accretion onto a supermassive black hole, rather than a starburst. These results are consistent with recently published ISO, ASCA, and VLBI data.On the other hand, there is no unambiguous optical or near-infrared spectroscopic evidence for an AGN in ULIGs optically classified as H II-region galaxies (∼ 30 % of the -2whole sample) or as LINERs (∼ 40 %). The apparent lack of an energetically important AGN in these objects supports the results from recent mid-infrared spectroscopy with ISO. Photoionization by hot stars from a recent starburst appears to be the dominant source of ionization in the objects with H II region-like spectra, while both hot stars and shocks may contribute to the ionization in ULIGs with LINER-like spectra. The weaker Hβ and Mg Ib stellar absorption features, larger Hα emission equivalent widths and bluer optical continuum colors in objects of higher infrared luminosities suggests that the starburst took place more recently ( ∼ < few × 10 7 yrs) and/or is more important (∼ 10 % of the galaxy mass) in ULIGs than in their lower luminosity counterparts.As found in optically-selected starbursts, the emission-line gas in ULIGs is dustier than the stellar population which is producing the optical continuum. The color excess derived from the Balmer line ratio does not si...