Abstract
We present B, R, and Hα images for a total of 114 nearby galaxies (vhelio < 4000 km s-1) that, with exception of nine objects, are classified as blue compact dwarfs (BCDs). BR integrated magnitudes, Hα fluxes and Hα equivalent widths for all the objects in the sample are presented. A new set of quantitative, observational criteria for a galaxy to be classified as a BCD is proposed. These criteria include a limit on the K-band luminosity (i.e., stellar mass; MK > -21 mag), peak surface brightness (μB,peak < 22 mag arcsec-2), and color at the peak surface brightness (μB,peak - μR,peak ≲ 1). Hα emission is detected in all but three sample galaxies. Typical color, absolute magnitude, and Hα luminosity are (B-R) = 0.7 ± 0.3 mag, MB = -16.1 ± 1.4 mag, and log (LHα) = 40.0 ± 0.6 (ergs s-1). Galaxies morphologically classified as nE and iE BCDs within our sample show lower Hα equivalent widths and redder colors, on average, than the iI- and i0-type BCDs. For most of the galaxies the presence of an evolved stellar population is required to explain their observed properties; only the most metal-poor BCDs (e.g., I Zw 18, Tol 65) are still compatible with a pure, young burst. The flux-calibrated and WCS-compliant images in this Atlas are individually available through the NASA/IPAC Extragalactic Database (NED) image server and collectively through a dedicated Web page.
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