At redshift z~1.7 the Universe was at the peak of its star-formation activity. It is thus a puzzle why some galaxies, many of them very massive (M* ⩾ 1011 M⊙), had already chosen to stop forming stars. These ultra-massive galaxies, guaranteed to be the central galaxies of their host dark matter halos, must have attained very high rates of star formation to assemble their stellar masses in such a short amount of time. Using the largest (to date) K-selected gzKs survey of passive galaxies (in an effective area of ~ 27.5 deg2) we study the demographics of these dead monsters, hoping to help understand the quenching mechanism that shut them down.

The TAURUS Tunable Filter (TTF) affords a new approach to observational cosmology, allowing a wide field (10 arcmin) to be imaged monochromatically in contiguous wavelength intervals (6–60 Å bandpass) over the R and I bands. In a 200 s exposure with the AAT, the TTF can detect Hα emission powered by star formation rates as low as 0·1 M⊙ yr−1 at z = 0·08 and 1 M⊙ yr−1 at z = 0·24 in 2 arcsec seeing (cf. 0·26 M⊙ yr−1 for the LMC). In this paper we describe an emission-line survey currently under way using the TTF on the AAT to detect redshifted Hα over the ranges z = 0·06–0·1 and z = 0·22–0·26. Such detections will be of timely interest to the Southern HI Sky Survey which is motivated along similar lines.

In the regions of highest optical obscuration and infrared confusion, only 21-cm emission can be used to find galaxies in the Zone of Avoidance. A feasibility study conducted with the 300-ft telescope successfully uncovered galaxies which seem to be consistent with populations of optically-selected low surface brightness galaxies. A complete survey is currently being conducted in the north with the Dwingeloo telescope. The big breakthrough should come in the south, however, with the advent of the Parkes telescope multibeam system.