The dwarf galaxy population of the Dorado Group down to M-v approximate to-11

We present V and I CCD photometry of suspected low surface brightness dwarf galaxies detected in a survey covering similar to2.4 deg(2) around the cen tral region of the Dorado group of galaxies. The low surface brightness gal axies were chosen based on their sizes and magnitudes at the limiting isoph ote of 26 V mu. The selected galaxies have magnitudes brighter than V appro ximate to 20 (M-V approximate to -11 for an assumed distance to the group o f 17.2 Mpc), with central surface brightnesses mu (0) > 22.5 V mag arcsec(- 2), scale lengths h > 2 ", and diameters greater than or equal to 14 " at t he limiting isophote. Using these criteria, we identified 69 dwarf galaxy c andidates. Four of them are large very low surface brightness galaxies that were detected on a smoothed image, after masking high surface brightness o bjects. Monte Carlo simulations performed to estimate completeness, photome tric uncertainties and to evaluate our ability to detect extended low surfa ce brightness galaxies show that the completeness fraction is, on average, >80% for dwarf galaxies with -17 < M-V < -10.5 and 22.5 < <mu>(0) <25.5 V m ag arcsec(-2), for the range of sizes considered by us (D <greater than or equal to> 14 "). The V-I colors of the dwarf candidates vary from -0.3 to 2 .3 with a peak on V-I = 0.98, suggesting a range of different stellar popul ations in these galaxies. The projected surface density of the dwarf galaxi es shows a concentration toward the group center similar in extent to that found around five X-ray groups and the elliptical galaxy NGC 1132 studied b y Mulchaey & Zabludoff, suggesting that the dwarf galaxies in Dorado are pr obably physically associated with the overall potential well of the group.