HI-observations of dwarf galaxies in the Local Supercluster

We have observed 71 dwarf galaxies of low surface brightness using the 100-m radio telescope at Effelsberg in a search for new members of 27 northern galaxy groups with characteristic distances of 8 to 15 Mpc. We present radial velocities, HI-fluxes, and HI line widths for 17 detected galaxies as well as upper limits for the remaining undetected objects. Almost all detected dwarf galaxies are physical members of the corresponding group with a mean radial velocity difference of -9 +/- 45 km s(-1) with respect to the principal galaxy in each group. Our sample of new dwarf members of nearby groups has a median radial velocity of 700 km s(-1), a mean blue absolute magnitude of -12.7 mag, a mean linear diameter of 2.5 kpc, and a mean M-HI/L-B ratio of 1.1 M-circle dot/L-circle dot. The Ir galaxy d1217+4703 in the Canes Venatici I cloud turns out to be a very gas-rich galaxy with M-HI/L-B = 6.5 in solar units.