NOIRCAT - the Northern HIPASS Optical/IR Catalogue

We present the Northern HIPASS (H I Parkes All-Sky Survey) Optical/Infrared Catalogue (NOIRCAT), an optical/near-infrared (NIR) counterpart to the Northern HIPASS Catalogue (NHICAT). Of the 1002 sources in NHICAT, 655 ( 66 per cent) have optical counterparts with matching optical velocities. A further 85 ( 8 per cent) sources have optical counterparts with matching velocities from previous radio emission-line surveys. We find a correlation between the gas and stellar content of the NOIRCAT sources. Our H I-selected sample of isolated galaxies also presents a wider range in NIR colours than previous optically selected studies of regular, isolated galaxies. All H I detections in optically unobscured fields could be matched with either a NASA/IPAC Extragalactic Database optical counterpart, or a galaxy visible in Second Palomar Observatory Sky Survey or Digitized Sky Survey images. However, as over 200 of these matched galaxies have no velocity information, further follow-up observations are needed to confirm the matches, and hence confirm or deny the existence of dark galaxies in this data set.