de Blok, WillemZwaan, M ADijkstra, MBriggs, FranklinFreeman, Kenneth2015-12-130004-6361http://hdl.handle.net/1885/88118We present results of two 21-cm HI surveys performed with the Australia Telescope Compact Array in the nearby Centaurus A and Sculptor galaxy groups. These surveys are sensitive to compact HI clouds and galaxies with HI masses as low as ∼3 × 106 M⊙,Keywords: Acoustic noise; Computer simulation; Hydrogen; Poisson distribution; Satellites; Telescopes; Luminosity function; Galaxies Galaxies: luminosity function, mass function; Intergalactic medium; ISM: clouds; Radio lines: ISM20022015-12-12