TO APPEAR IN The Astrophysical Journal Supplement. Preprint typeset using L A T E X style emulateapj v. 26/01/00 THE CARNEGIE-IRVINE GALAXY SURVEY. I.OVERVIEW AND ATLAS OF OPTICAL IMAGES LUIS C. HO 1 ,ZHAO-YU LI 1,2 ,AARON J. BARTH 3 ,MARC S. SEIGAR 4,5 , AND CHIEN Y. PENG 1,6 To appear in The Astrophysical Journal Supplement. ABSTRACT The Carnegie-Irvine Galaxy Survey (CGS) is a long-term program to investigate the photometric and spectro- scopic properties of a statistically complete sample of 605 bright (B T < 12.9 mag), southern (δ< 0 ◦ ) galaxies using the facilities at Las Campanas Observatory. This paper, the first in a series, outlines the scientific motiva- tion of CGS, defines the sample, and describes the technical aspects of the optical broad-band (BVRI ) imaging component of the survey, including details of the observing program, data reduction procedures, and calibration strategy. The overall quality of the images is quite high, in terms of resolution (median seeing ∼ 1 00 ), field-of-view (8. 0 9×8. 0 9), and depth (median limiting surface brightness ∼ 27.5, 26.9, 26.4, and 25.3 mag arcsec -2 in the B, V , R, and I bands, respectively). We prepare a digital image atlas showing several different renditions of the data, including three-color composites, star-cleaned images, stacked images to enhance faint features, structure maps to highlight small-scale features, and color index maps suitable for studying the spatial variation of stellar content and dust. In anticipation of upcoming science analyses, we tabulate an extensive set of global properties for the galaxy sample. These include optical isophotal and photometric parameters derived from CGS itself (Paper II, Li et al. 2011), as well as published information on multiwavelength (ultraviolet, U -band, near-infrared, far-infrared) photometry, internal kinematics (central stellar velocity dispersions, disk rotational velocities), environment (dis- tance to nearest neighbor, tidal parameter, group or cluster membership), and H I content. The digital images and science-level data products will be made publicly accessible to the community. Subject headings: atlases — galaxies: fundamental parameters — galaxies: general — galaxies: photometry — galaxies: structure — galaxies: surveys 1. MOTIVATION The structural components of a galaxy bear witness to the major episodes that have shaped them during its life cycle, and, as such, provide crucial fossil records of the physical processes operating in galaxy formation and evolution. Morphological clues have long guided our intuition about galaxy formation (Gott 1977; Wyse et al. 1997). The two most conspicuous luminous components modulated along the Hubble sequence— the bulge and the disk—have been the main focal points of our modern concepts of how galaxies were assembled. The roughly spheroidal shape of elliptical galaxies and the bulges of spiral galaxies, along with the recognition of their generally evolved stellar population, signifies rapid, dissipationless collapse at an early epoch. The r 1/4 profile (de Vaucouleurs 1948) of ellipti- cals and classical bulges is often interpreted as a signature of violent relaxation (van Albada 1982) resulting from rapid as- sembly through major mergers. By contrast, the flattened con- figuration of an exponential disk (Freeman 1970), along with their younger, more mixed stellar populations, suggests that more gradual, dissipative processes have been operating, and are still ongoing today. With the advent of modern, large-format detectors and the accompanying improvement in linearity, dynamic range, and image resolution, our view of galaxy morphology has grown steadily more elaborate, to the point that, in many instances, the classical picture of a bulge plus disk no longer suffices to describe the complex details seen in state-of-the-art galaxy im- ages. While an r 1/4 law still provides a good first-order ap- proximation to the overall light distribution of many elliptical galaxies, at least in images taken with typical ground-based res- olutions 7 , the situation is considerably more complicated for the bulges of disk galaxies. The central light distribution of not only spirals, but also S0s, shows a variety of shapes (e.g., An- dredakis & Sanders 1994; Courteau et al. 1996; de Jong 1996; MacArthur et al. 2003; Laurikainen et al. 2005; Graham & Worley 2008; Gadotti 2009), which are often well represented by a Sérsic (1968) r 1/n profile, with n ranging from 1 (pure ex- ponential) to 4 (standard de Vaucouleurs value). Imaging with the Hubble Space Telescope reveals an even greater degree of structural heterogeneity, including nuclear disks, nuclear spi- rals and rings, central nuclei and star clusters, and intricate dust lanes (e.g., Carollo et al. 1997; Böker et al. 2002; Seigar et al. 2002). This rich variety of kinematically cold structures in the cen- tral regions of galaxies compels us to reevaluate the very def- inition of a “bulge.” Evidently many bulges are not the old, dead, fully established systems we once thought. Instead, they appear to have experienced a much more gradual, protracted 1 The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 2 Department of Astronomy, School of Physics, Peking University, Beijing 100871, China 3 Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697-4575 4 Department of Physics & Astronomy, University of Arkansas at Little Rock, 2801 S. University Avenue, Little Rock, AR 72204 5 Arkansas Center for Space and Planetary Sciences, 202 Old Museum Building, University of Arkansas, Fayetteville, AR 72701 6 NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia, Canada V9E 2E7 7 In detail, the global profiles of ellipticals span a wider range of shapes (see Kormendy et al. 2009 for a recent, comprehensive review). At sub-arcsecond resolu- tion, for instance as afforded by the Hubble Space Telescope, the central light distributions show significant additional deviations from the global, outer profiles (e.g., Lauer et al. 1995; Ravindranath et al. 2001). 1