Deep observations with the Parkes 21-cm multibeam system

We report on a preliminary analysis of a 5600 sec per point survey of 32 sq uare degrees in Centaurus, carried out with the Parkes 13-beam system. The signal-to-noise ratio is found to improve as root t(obs) for the whole inte gration. We have detected 102 HI sources between +250 and +12,700 km s(-1) either by eye or by using the new galaxy-finding algorithm PICASSO. Over ha lf of these are new HI detections. Around a dozen of these are not associat ed with catalogued galaxies and, in two of these cases, we have not identif ied an optical counterpart on the Digitized Sky Survey. Arguments are put f orward to explain why deep integrations are needed to find low surface brig htness objects.