We have completed a 21-cm survey of a 600 square degree region of the Centaurus A group of galaxies at a redshift of \sim 500 km { s } ^ { -1 } as part of a larger survey of the entire southern sky .
This group of galaxies was recently the subject of a separate and thorough optical survey ( Côté et al .
1997 ) , and thus presented an ideal comparison for us to test the survey performance .
We have identified 10 new group members to add to the 21 already known in our survey area .
Six of the new members are previously uncatalogued galaxies , while four were catalogued but assumed not to be group members .
Including the 7 known members outside of our survey area , this brings the total known number of Cen A members to 38 .
All of the new H i detections have optical counterparts , most being intrinsically very faint ( M _ { B } > -13.0 ) , late-type low surface brightness dwarfs .
Most of the new members have H i masses only a few times our survey limit of 10 ^ { 7 } M _ { \odot } at an assumed distance for the group of 3.5 Mpc , and are extremely gas-rich , with a median M _ { HI } /L _ { B } > 1 .
Our limiting H i sensitivity was actually slightly worse than the H i follow-up observations of the Côté et al .
optical survey , yet we have already increased the known number of group members by 50 % using an H i survey technique . While we have increased the known number of members by \sim 50 % , these new members contribute < 4 % to its light .