We report on a new method of determining radio source positions with the Parkes radio telescope. The method is appreciably quicker than, but has a comparable accuracy to, established methods such as orthogonal scanning. It has been particularly useful during 1989 in tracking the Voyager II spacecraft as it approaches Neptune; a method of accurately pointing at the source of the radio signal was required without the signal degradation which is introduced by moving appreciably off source.

A search has been made using the Buckland Park air shower array for evidence of any excess of events from the direction of the recent supernova in the Large Magellanic Cloud. Upper limits resulting from this search and their significance are discussed in this paper.

The transfer of kinetic energy between cosmic rays and charged dust grains is investigated. The time required for heating of the dust grains due to Coulomb interactions is estimated and compared with the heating time due to ionisation losses by the cosmic rays. Heating of dust grains by cosmic rays is examined in connection with the FIR–radio correlation in galaxies: even for the most favorable conditions, including a high energy density in low-energy, ≲ 100 keV, cosmic rays, the conclusions are equivocal.

Recent results have shown that Long-Period Variables (LPVs) with periods in the range 100 to 250 days have ages ~ 10 Gyr. We have studied the kinematics of a sample of such variables in the Large Magellanic Cloud (LMC). A comparison with the kinematics of other populations (H I gas, CO molecular clouds, planetary nebulae, CH stars and old clusters) indicates that all populations younger than the old LPVs are dominated by a single common rotating disk, with the kinematics of the old LPVs being the first to indicate the presence in the LMC of a spheroidal population, with little or no rotation and a velocity dispersion ~ 6 times larger than that of the H I gas.

On the basis of (R — I) colours it has been suggested that the N stars (the cool carbon stars) occupy a very restricted region in the M b01 — log T e diagram (T e = 3300 to 3500 K) M b01 ~ —3), falling on the normal giant sequence, but hotter than the M variables. This appeared somewhat puzzling in view of the variability of many of the carbon stars and their large range of periods, which suggested that the N stars ought perhaps to have similar temperatures to the variable M stars. In order to compare the continua of the M stars and N stars within the range of the R and I filters, and also to determine the continuum between the molecular bands, photometric observations were made of 20 M and N stars at carefully chosen wavelengths with 30Å resolution.

A standard procedure for the simulation of galaxies is to replace the ∼ 1011 stars by ∼ 104 particles. These particles are assumed to have equal mass and their distribution in space produces a mass density ϱ which mimics the average mass density of the stars. From the mass density of the particles the gravitational forces between the particles can be computed. In the literature two methods have been used to compute these forces.

Recent astronomical measurements of solar and celestial X-radiation have led to renewed interest in strong shock-wave phenomena arising from explosions which occur on an astrophysical scale as in solar flares, novae and in supernovae. Although on a much smaller scale, the ‘Starfish’ nuclear explosion at an altitude of 400 km over Johnson Island in 1962, provides a useful test of current understanding in this field.

Although only three antennas of the Australia Telescope Compact Array are currently operational, we have made use of the technique of bandwidth synthesis to make an image of the radio galaxy 2152 – 69. The three baselines were used to observe the source at three different frequencies, effectively resulting in nine baselines, which have been used to produce an image with a surprisingly high dynamic range, and with a slightly higher resolution than any existing image.

The production of such a worthwhile result, despite being made with a small subset of the capabilities of the Australia Telescope, bodes well for the future operation of the instrument.

We report spectroscopic and photometric observations of the new DQ Hercuis system 1H0542-407, recently discovered by us to be the optical counterpart of a HEAO-1 X-ray source. Medium resolution spectroscopy using the AAT in the region λ3930 to λ4960 conducted over consecutive nights shows radial velocity variations at periods of ∼ 1910 s, consistent with the white dwarf rotation period, and 5.7 h, in agreement with the orbital period derived from our EXOSAT observations. The K semi-amplitude velocities are ∼ 50 and 20 km s-1 respectively, leading to a mass function f(M) = 3.3 ± 0.6 × 10-3M⊙ and an orbital inclination close to 20°. The emission line profiles are characterized by simple Gaussians whose FWHM vary at the rotation period. A time series analysis of high resolution photometry conducted on the ANU 2.3 metre telescope reveals the presence of several periodicities, including the orbital sidebands. The dominant sideband (Vr − Vo) arises from X-rays reprocessed in a region corotating at the orbital frequency. A model is developed for 1H0542-407 which indicates that the accretion disk is disrupted at ∼5R wd by the primary’s magnetic field. The short period velocity variations arise within the magnetosphere. A white dwarf magnetic field strength of < ∼ 3 MG is implied.

Globular clusters in the Galaxy are all old objects, with ages of about 1010 years. The LMC is quite different: its globular clusters have ages anywhere between about 5 × 106 years and 1010 years. It is important to find out why globular clusters can form now in the LMC but not in the Galaxy; the galactic globulars play a major role in our picture of the early history of the Galaxy, and it is obviously desirable that we should understand the conditions under which these clusters can form.

The stellar interferometer at Narrabri Observatory measures the angular diameter of hot, bright stars. It does this by matching the observed intensity correlation from two detectors, as a function of separation between the detectors, with that from a uniform disk (see Hanbury Brown et al.). When this measurement is taken in conjunction with experimental determinations of the monochromatic flux received at the Earth, the effective temperature of the star, Te, can be determined. However, if the star being observed is rotating rapidly, comparison with a uniform disk is of doubtful validity. Owing to its rotation the shape of the star will be distorted, and its effective temperature will vary over the surface (being apparently hotter at the poles). Therefore the measured angular diameter of the star will be different, and will change with the orientation of the star’s axis of rotation in the sky.

A Dark Matter Workshop was held at the CSIRO Radiophysics Laboratory in Marsfield, Sydney, on 24–25 February 1994. The workshop, sponsored by the Australia Telescope National Facility (ATNF), was a meeting of dark matter (DM) specialists as well as astronomers interested in the field, and attracted about 80 participants from nine institutions. The program consisted of 22 oral contributions (15–45 minutes), followed by lively discussions, as well as podium discussions at the end of each day. Abstracts of most of the contributions are presented here, arranged by subject groups which range from ‘Gravitational Lensing and DM in Clusters’, ‘DM in Elliptical Galaxies’, ‘The Nature of DM’, and ‘The Shapes of Dark Halos’ to ‘Alternatives to DM’.

Expressions for the probability per unit time of the emission of a Langmuir wave by both massive and massless neutrinos moving in a medium are derived using finite-temperature field theory. A comparison between this process and the analogous emission from an electron is made, and possible implications of this process for the explosion mechanisms of type II supernovae are briefly discussed.

Photographic observations of Flare Stars in association with Slee, Higgins and Patston, T Association patrols, photographic photometry of selected variable stars in association with Bateson of New Zealand and surveillance of comets brighter than V = 13m, in association with Candy of the United Kingdom constitute the principal fields of research of Page Observatory (private), situated 7 miles North of Brisbane. A recently constructed f2.9 8in/12.5in Schmidt telescope now serves as the main photographic instrument.

This paper describes a system utilising a sapphire-loaded superconductor cavity to provide a high-stability oscillator signal for use in VLBI observations.

Geomagnetic storm sudden commencements (ssc) and sudden increases (si) can be caused by either a propagating discontinuity (i.e. a hydromagnetic shock or blast wave) in the interplanetary plasma or by the convection past the Earth of a discontinuity in the ambient solar plasma flow.

Dodson and Hedeman discovered an unexpected effect in the occurrence of solar proton events as revealed by polarcap absorption (PCA). When the 48 events in Bailey’s Catalog of the Principal PCA Events, 1952-1963 are distributed with the phase of the moon there is a gap of several days near full moon; also, many more events occur when the moon waxes than when it wanes. Dodson and Hedeman did not find similar, apparent departures from random distribution either with a mean solar rotation period of 27.3 days or for solar flare events. They concluded that ‘at the present time it is not clear whether the 29.5 day “effect” is related to the sun or the moon or is only a statistical accident’.