Searching at 21 centimeters for galaxies behind the Milky Way

Known galaxies are rare in the quarter of the sky which is obscured by the Galactic disk. A census of galaxies there (and their velocities) would be valuable for studies of the large-scale structure of the extragalactic universe and of deviations from the Hubble flow. A pilot study has been carried out at 21 cm covering about 1900 arbitrarily chosen points in the zone of avoidance and 16 new galaxies have been detected, some of whose line profiles have the signature of spirals, while others do not. Several other possible detections require confirmation. For comparison, a similar study was carried out for a blindly chosen set of points in the 'clear' region at higher latitudes. Having demonstrated the capabilities of the method, the requirements for a fully sampled study of the whole zone of avoidance are considered.