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.

Over 600 pulsars are now known, almost all of which lie in our Galaxy. Most pulsars have periods between 0 · 1 and a few seconds, but a very important sub-class, the ‘millisecond’ pulsars, have much shorter periods. Millisecond pulsars are often in a binary orbit with another star, suggesting that their short periods are a result of accreting mass from the companion star. They are also extraordinarily good clocks, with a stability comparable to that of the best atomic clocks. This combination of extreme period stability and binary motion has led to some very important results, including the first observational evidence for gravitational radiation and the first evidence for extra-solar planetary systems. It is probable that pulsars will be used to define the long-term standard of terrestrial time. A search of the southern sky using the Parkes radio telescope has found several millisecond pulsars which will make an important contribution to these precision-timing programs.

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.

The main features of visual searching for supernovae in other galaxies by amateur astronomers are described, and an outline is given of the results which have been achieved so far by this method. A short comparison is made between visual searching and photographic searching. A more extensive comparison is then made between visual searching for supernovae in Australia, and the work of the Berkeley Automatic Supernova Search at Leuschner Observatory, since 1986. Among the conclusions is the claim that a competent visual observer could produce similar results to those produced by the Berkeley group if a telescope of similar aperture was used for a similar amount of observing time, and from a good observing site. Indeed, visual searching might possibly produce more results, and such a search would only cost a small fraction of what was spent on this automatic search. It would be a worthwhile project to conduct a visual search with a suitably designed 76-cm telescope, or a one metre telescope, over a period of a few years, to see if this conclusion could be supported in practice.

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.

The long-standing enigma of audible sound production simultaneous with the distant flight of large meteor fireballs is becoming increasingly well understood. Utilising Keay’s model linking the production of ELF/VLF electromagnetic radiation with turbulence in the fireball’s plasma trail, it has proved possible to adapt Ceplecha’s fireball model to include the criteria for turbulence and the consequent production of electrophonic sounds, yielding an excellent match with observations. It is becoming apparent that other geophysical phenomena also have the capacity to produce electrophonic sounds. These include aurorae, lightning and earthquakes.

It is shown that numerical integration of the equation of polarisation transfer for generalised Faraday rotation provides an alternative to mode-coupling theory for treating propagation through a quasi-transverse (QT) region. At a QT region, where the sign of the component of the magnetic field along the ray path reverses, the sense of circular polarisation reverses below a frequency ωt, and is unchanged above ωt. There is a long-standing difficulty in the interpretation of the polarisation of radio emission from bipolar regions on the Sun: observational and theoretical estimates of ωt appear inconsistent. The alternative approach may help resolve this difficulty.

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.

Shock drift acceleration of the electrons which produce herringbone structure in type II bursts is considered. A non-coplanar component of the magnetic field within the shock front and an electric field across the shock are taken into account. A quantitative difficulty with shock drift acceleration is identified, and possible ways of overcoming the difficulty are outlined.

The effect of impulsively turning off the dissipation in an existing model for energy propagation through Alfvénic fronts into the coronal site of energy release in a solar flare is examined. In the optimum case of impedance matching, the flux tube re-stresses on a much longer timescale than it relaxes, suggesting an explanation for the timescales observed in homologous flares.

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 cosmic ray ground-level enhancement (GLE) of 24 October 1989 was the last of a series of GLEs associated with the same solar active region. Intensity enhancements were observed by at least 31 neutron monitors in the worldwide network, with the largest increase (~200%) observed at South Pole, Antarctica around 20:30 UT. Using a least-squares model fit to all available neutron monitor data, spectra, apparent source directions and particle pitch angle distributions have been derived. The effect of disturbed geomagnetic conditions has also been taken into account.

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.

This paper is a preliminary report on the flux density monitoring of calibration sources used at the Molonglo Observatory Synthesis Telescope. We show two examples of large amplitude variability at 843 MHz which we attribute to refractive scintillation in the Galactic interstellar medium.

The Cosmology Distinction Course is a new one-year course to be introduced for Year 12 candidates in the 1994 Higher School Certificate examinations in NSW. It is one of three challenging courses of study that will enrich the HSC for talented students who accelerate and complete part of the HSC one year early. The courses will be taught through distance learning and will include residential seminars. They will be implemented on behalf of the Board of Studies by Charles Sturt University and the University of New England.

The Cosmology Course is organised into nine modules of course work covering historical and social aspects of cosmology, observational techniques, key observations and the various models developed—Newtonian, de Sitter, Friedmann, Lemaitre, steady-state, quasi-steady-state and big bang. Assessment will be through assignments, exams and a major project.

As the first Distinction Course in a scientific area, the Cosmology Course represents an exciting and important educational initiative that needs the cooperation of NSW astronomers and, in return, promises to benefit the astronomical and general scientific community in Australia.

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.