This article continues a series of publications (Georgiev et al. 1997; Makarova et al. 1997; Makarova et al. 1998) devoted to the study of the 3D- structure of the nearest scattered complex of galaxies in Canes Venatici (=CVn). Being situated near the Local Supercluster equator, the CVn cloud is projected onto other galaxy groups, which complicates the analysis of its structure and kinematics. About 90% of the population of the CVn cloud are irregular dwarf galaxies. Application of the Tully & Fisher (1977) method to them gives distance modulus estimates with a rather low accuracy: mag.
In large-scale images of irregular galaxies in several bands one can distinguish blue supergiants and use their luminosity to determine distance moduli with a typical error of about 0.4 mag (Karachentsev & Tikhonov 1994). All the six irregular galaxies studied here have corrected radial velocities V0 < 300 km/s, suggesting close distances. The results of our photometry confirm this suggestion.