Twelve supernova remnants in the Large Magellanic Cloud have now been observed with the Australia Telescope. These were all imaged in total intensity and where possible the linear polarisation was also mapped. In many respects this survey is similar to previous single-dish observations of Galactic supernova remnants, and comparisons are made with these results. Preliminary images are shown for several sources. The survey is continuing with additional array configurations and at other wavelengths.

Cosmic ray transient variations are signatures of the underlying solar processes which affect the heliomagnetic structure. They can be found in the data from surface systems, such as neutron monitors and muon telescopes, and from shallow underground muon telescopes. Although sometimes observable at all latitudes, the global distribution of the effects is important in determining the structures and causes. Three transient variation types are known, namely Forbush decreases, ground level enhancements, and quasi-periodic fluctuations. The latter category includes some variations which are, perhaps, too long-lived to be considered truly transient. In this review, the detection techniques and background of cosmic ray research are followed by a summary of some observations in each transient category. The heliomagnetic structures and dynamics inferred from such transients are discussed together with the possible impact such events can have on human activity.

Our knowledge of the universe comes from recording the photon and particle fluxes incident on the Earth from space. We thus require sensitive measurement across the entire energy spectrum, using large telescopes with efficient instrumentation located on superb sites. Technological advances and engineering constraints are nearing the point where we are recording as many photons arriving at a site as is possible. Major advances in the future will come from improving the quality of the site. The ultimate site is, of course, beyond the Earth’s atmosphere, such as on the Moon, but economic limitations prevent our exploiting this avenue to the degree that the scientific community desires. Here we describe an alternative, which offers many of the advantages of space for a fraction of the cost: the Antarctic Plateau.

A description is given of a radar facility operating in New Zealand which measures the atmospheric trajectories and hence heliocentric orbits of earth-impacting meteoroids having radiants with declinations +5° < δ < −30° down to a limiting radar meteor magnitude of +13 (corresponding to particle sizes of ~100 μm, masses ~10−6 g). The data handling capacity of the facility permits recording, orbit reduction and efficient presentation of orbital data using graphical packages to be carried out on a routine basis. The daily yield is ~1500 individual orbits with >3×105 secured to date; this is greater than the number determined in all previous meteoroid orbit surveys combined and forms a major southern hemisphere database for dynamical studies of the solar system meteoroid population.

Initially some simple analytical properties based on the annual Zürich relative sunspot number are established for the 22-year Hale solar magnetic cycle. Since about AD1850, successive maximum sunspot numbers in a Hale cycle are highly correlated. Also, a regression model for the reconstruction of the 22-year Hale cycle has been formulated from proxy tree-ring data, obtained from spruce trees growing at a high altitude site in White River National Forest in Colorado. Over a considerable fraction of the past 300 years to AD1986, the ring-index time series power spectrum exhibits a strong 22-year periodicity, and more recently a significant spectral peak (at the 95% confidence level) at approximately 11 years. The model shows that the greatest variation in ‘amplitude’ in the magnetic cycle occurs over the early decades of the eighteenth century, when the sample size is small. Thereafter, a nearly constant amplitude is maintained until about AD1880 when a break occurs in both phase correspondence and amplitude, extending over the next three cycles. From AD1950 the signal recovers phase with the solar cycle, with reduced but increasing amplitude.

Four tree ring-index site chronologies, representing standardised annual growth rates for spruce trees growing at high altitude sites in Colorado, have been employed as proxy data in a regression model for the annual variation of solar radio flux at 2800 MHz (F10·7) and the Catania sunspot area (Ac). These dendrochronological time series all exhibit significant power spectrum peaks at about 11 years and separately correlate with the annual values of Rz, F10·7 and Ac, as solar activity indicators. The two models constructed give the cyclic variation of F10·7 and Ac back to AD1673.

We have deduced the yearly averaged value of the solar diurnal variation as observed by a surface muon telescope and three underground muon telescopes over the years 1957 to 1985. This has allowed us to examine the temporal variation in both the latitudinal gradient Gz and the product of the parallel mean free path and the radial gradient of galactic cosmic rays during three consecutive solar cycles. The median rigidities of the primary particles being detected by the telescopes are 50 GV in the case of the surface muon telescope and greater than 150 GV in the case of the underground muon telescopes. We have compared our results with those of a similar study made from observations of the solar diurnal variation by neutron monitors and an ion chamber, which have median rigidities of response between 17 and 70 GV (Bieber and Chen 1991a). The product has a solar magnetic cycle dependence and our values are lower than those observed by neutron monitors, in agreement with the Bieber and Chen observation that reverses after a solar magnetic field reversal, in accordance with drift theories.

The effect of diffusive shock acceleration on a distribution of particles is explored for multiple shocks, taking into account adiabatic expansion between the shocks. Specifically, the spectral index is calculated numerically for two cases: a sequence of identical shocks, and a sequence of pairs of shocks with alternating shock strength. How these two cases evolve to the asymptotic limit is examined, and it is shown that the evolution of the paired-shock case can be described by a sequence of identical shocks with shock strength equal to the mean of the two.

The Fault Diagnosis Expert System for the Australia Telescope analyses ~12000 items of monitor data every minute that report the health and stability of specific components and signal pathways in the array. These data are divided into signatures which are matched against signatures of known failure modes to diagnose problems with the array. Knowledge about many of the failures is acquired by generating them in earlier tests. The system keeps a six-hour history of the detailed behaviour of all monitor data as well as the visibilities. It archives the data in half-hour intervals, characterising the interval with a small set of robust statistical estimators. An interactive graphical user interface allows the simultaneous display of twenty-four histories of either the 6-hour data or one week of the characterised data, together with options for plotting one history against another and for calculating their robust regression.

A grant from the Department of Employment, Education and Training and matching funding from the University of Western Sydney, Nepean, has allowed the construction of a teaching and public access observatory on the University’s Werrington North campus. The observatory consists of a lecture theatre for about 50 students, an office for administration and project/souvenir sales, and an enclosed office for research activities. The 6·5 m dome will house a fork-mounted 0·6 m (24 inch) Ritchey-Chrétien telescope working at f/10. There will also be two outside observation areas for tripod-mounted telescopes. The expected completion date for the entire project is mid-1994.

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.

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.

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.