The 1000 Brightest HIPASS Galaxies: Newly Cataloged Galaxies

The HI Parkes All-Sky Survey (HIPASS) is a blind 21-cm survey forextragalactic neutral hydrogen, covering the whole southern sky. The HIPASSBright Galaxy Catalog (BGC; Koribalski et al. 2002) is a subset of HIPASS andcontains the 1000 HI-brightest (peak flux density) galaxies. Here we presentthe 138 HIPASS BGC galaxies, which had no redshift measured prior to the Parkesmultibeam HI surveys. Of the 138 galaxies, 87 are newly cataloged. Newlycataloged is defined as no optical (or infrared) counterpart in the NASA/IPACExtragalactic Database. Using the Digitized Sky Survey we identify opticalcounterparts for almost half of the newly cataloged galaxies, which aretypically of irregular or magellanic morphological type. Several HI sourcesappear to be associated with compact groups or pairs of galaxies rather than anindividual galaxy. The majority (57) of the newly cataloged galaxies lie withinten degrees of the Galactic Plane and are missing from optical surveys due toconfusion with stars or dust extinction. This sample also includes newlycataloged galaxies first discovered in the HI shallow survey of theZone-of-Avoidance (Henning et al. 2000). The other 30 newly cataloged galaxiesescaped detection due to their low surface brightness or optical compactness.Only one of these, HIPASS J0546-68, has no obvious optical counterpart as it isobscured by the Large Magellanic Cloud. We find that the newly catalogedgalaxies with |b| > 10 are generally lower in HI mass and narrower in velocitywidth compared with the total HIPASS BGC. In contrast, newly cataloged galaxiesbehind the Milky Way are found to be statistically similar to the entire HIPASSBGC. In addition to these galaxies, the HIPASS BGC contains four previouslyunknown HI clouds.