The Molonglo Observatory Synthesis Telescope (MOST), which at present images a fully synthesised 70′ field in 12 h, is being converted to enable observing modes which extend the field size to 160′. The new observing modes will allow the MOST to survey completely the sky south of δ = −30° to a (5σ) sensitivity limit of about 5 mJy. The result will be a catalogue of over 400,000 radio sources with a spatial density of less than 1 source per 100 beam areas, providing the foundation for a number of novel astronomical and cosmological investigations. The conversion involves construction of 352 low-noise HEMT preamplifiers, 88 digitally controlled UHF quad phase shifters, 88 mixers and IF sections, a new communication and control system, and several other new sub-systems. The project has been funded and developments are well advanced.

We demonstrate the presence of a cluster of hot, population I stars at the very centre of the Galaxy, using the depth of the first overtone band of CO and the presence of emission in He I 2 ·058 μm and [Fell] 1·644μm to identify stars. The cluster is very compact and comprises at least several hundred stars. They lie close to the nonthermal radio source Sgr A* and dominate the luminosity and mass loss of the Galactic core. Their presence suggests that a starburst occurred at the Galactic centre.

We discuss the basic concept and the problems of magnetic braking via magnetically controlled hot plasmas in late-type stars. We investigate the magnetic braking process in special magnetic field structures in both single stars and binaries. We find that in single solar-type stars, the high-order component of the observed complicated fields can account for the braking rate of the present Sun. However, this component cannot account for the braking rate of young solar-type stars, even though this field is much stronger than the simple (monopolar or dipolar) field usually adopted in braking models. For magnetically interacting cataclysmic binaries, the magnetic fields of the white dwarf greatly change the magnetic fields on the main-sequence secondaries. In particular, in synchronously rotating magnetic CVs (AM Herculis systems) magnetic braking may even turn off if the white dwarf magnetic field is sufficiently strong. These results suggest that the magnetic field structure has a crucial effect on magnetic braking.

The Papa camera is a photon-counting array detector that uses optical encoding to locate photon events on the output of a microchannel plate image intensifier. The Sydney University camera is a 256×256 pixel detector which can operate at speeds greater than 1 million photons per second and produce individual photon coordinates with a deadtime of only 300 ns. It uses a new Gray coded mask-plate which permits a simplified optical alignment and successfully guards against vignetting artifacts.

We have designed and manufactured a multi-purpose electronic, computer-operated blink-comparator and measuring engine. It has been specifically designed to facilitate the examination of stellar images on Uppsala Schmidt photographic plates, identify and establish coordinates of new suspect variable stars appearing on the plates being examined, and also to derive photometric values for those stars manifesting variability.

We review the magnetic locking of the white dwarf and the companion star in AM Herculis-type binaries for various white dwarf magnetic field structures, and compare the theoretical results with observations. The model in which the white dwarf has a dipole plus a quadrupole field is found to be in closest agreement with the recent observations.

We discuss the expected properties of shocks in molecular clouds when the effect of a magnetic field is included. The results suggest that shocks should have magnetic precursors, and may be C-shocks rather than J-shocks, but the observations are not obviously consistent with this prediction. The effect of these shock properties on cloud collisions triggering star formation is discussed.

Astrometric CCD observations have been made of wide (~3 to 80 arcsec) southern binary pairs using the 0·6 m telescope at MSSSO. Separations ρ and position angles (PA) have been calibrated against known astrometrie pairs, and have rms uncertainties of 0·16 arcsec and 7·8/ρ degrees (ρ in arcsec) respectively. These stars have not been well studied; typically they have not been measured since approximately 1930, and 52% of them have been observed only once prior to our observations. A comparison has been made with values published in the Washington Double Star (WDS) catalogue. Of the 304 pairs measured in the declination range −60° to −70°, 82% show no evidence of motion since the last observation.

Charles Todd, who established the Adelaide Observatory on West Terrace in 1860, retired as Government Astronomer at the end of 1906. In 1908 the meteorological duties of the Observatory were taken over by the Commonwealth, and the Observatory lost most of its staff. Following the promotion of George Dodwell to the position of Government Astronomer in 1909, the Observatory was slowly re-established and undertook a range of astronomical and other work, which is described in detail in this paper. The Observatory was transferred to the University of Adelaide in 1940 and this is often taken as the closure of the Observatory. Dodwell finished working as Government Astronomer in 1952.

We investigate the structure of inhomogeneous accretion shocks in magnetic white dwarfs. We find that bremsstrahlung cooling still plays an important role in determining the structure of the post-shock region, even when its cooling timescale is much longer than the cyclotron cooling timescale at the shock surface. Our calculations also show that a substantial amount of the accretion energy is dissipated at the base of the post-shock region through emission of bremsstrahlung radiation.

We have compared the spectra of six Type Ia supernovae, at ages between 4 and 404 days after maximum light, to see whether all show similar evolutionary behaviour. We find that the spectral lines between 6800 Å and 8000 Å follow a smooth evolutionary trend, but that lines redward of 8000 Å show significant differences. SN 1987I and SN 19880 show extra emission over a broader wavelength region, possibly due to OI 8446 Å emission which would indicate higher envelope densities for these objects. Our results are consistent with the trend of expansion velocity with parent galaxy type reported by Branch and van den Bergh (1993). Variations within the class of Ia SNe may affect their use as standard candles.

The Australia Telescope Compact Array has been used for observations, with arcsecond resolution, of the HII region N159 in the Large Magellanic Cloud. Images at 5 GHz reveal a second compact continuum component which has no obvious counterpart at optical and infrared wavelengths. Observations of HI 10α recombination-line emission, and HI and H2CO absorption, suggest that the object is a compact HII region embedded in a dense obscuring cloud on the edge of N159.

The radio galaxy B1610–605 within the Abell cluster A3627 has a low-brightness tail extending at least 26 arcmin from the nucleus of the 14 · 5m galaxy. The structure of this tail has been explored using observations with the Molonglo Observatory Synthesis Telescope (MOST) and the Australia Telescope Compact Array (ATCA). We present details of the brightness, width and alignment of the tail. The single tail expands and brightens rapidly within 2 arcmin of the nucleus. Confinement by the pressure of the cluster medium maintains a low but constant brightness for the tail between 10 and 25 arcmin. There are indications of turbulence down the tail but the position of the ridge remains within 1 · 6 arcmin of the initial alignment throughout its length.