Publications of the Astronomical Society of Australia

Research Article

AAT/WFI Observations of the Extragalactic HI Cloud HIPASS J1712-64

Geraint F. Lewisa1, Michael J. Irwina2, Rodrigo A. Ibataa3 and Brad K. Gibsona4

a1 Anglo-Australian Observatory, PO Box 296, Epping, NSW 1710, Australia;

a2 Institute of Astronomy, Madingley Rd, Cambridge, CB3 0HA, UK;

a3 Observatoire de Strabourg, 11, rue de l'Universite, F-67000, Strasbourg, France; ibata@pleiades.u-strasbg.frv

a4 Centre for Astrophysics & Supercomputing, Swinburne University, PO Box 218, Hawthorn, Victoria 3122, Australia;


AAT/WFI optical images of a candidate extragalactic HI cloud, HIPASS J1712–64, are presented. The g and r band CCD mosaic camera frames were processed using a new data pipeline recently installed at the AAO. The resultant stacked images reach significantly deeper levels than those of previous published optical imaging of this candidate, providing a detection limit M g ˜ −7 at a distance of 3 Mpc, the inferred distance to HIPASS J1712–64. However, detailed analysis of the images fails to uncover any stellar population associated with the HI emission. If this system is a member of the Local Group then it is pathologically different to other members. Hence, our observations reinforce earlier suggestions that this HI cloud is most likely Galactic in origin and not a Local Volume dwarf galaxy.

(Received February 11 2002)

(Accepted May 03 2002)


  • galaxies: dwarf;
  • Local Group;
  • techniques: image processing