The overall aim of the planned astronomical programme at Hobart (University of Tasmania) is to obtain stellar and planetary spectra in the ultra-violet, visible, and infrared regions of the spectrum. The major instruments to be used are a 16-inch telescope, a 40-inch telescope, and a solar spectrograph. Included in the project is a programme of laboratory studies, aimed at making quantitative comparisons of several of the most efficient methods for detecting and recording spectra from astronomical objects with low levels of flux. In addition, several new methods will be investigated. These will be referred to later in this paper.

Using a complete sample, we have looked for correlations in position between radio sources with S 408 ≥ 1 Jy in the Molonglo Reference Catalogue (MRC) and rich clusters of galaxies in the Abell, Corwin and Olowin catalogue (ACO). Within a projected radius of 100 kpc of the cluster centre, we find an overdensity of radio sources similar to that seen by Robertson and Roach (1990). They attributed this feature to centrally located dominant cluster galaxies. We confirm this hypothesis by looking at the morphology of the clusters within this peak and by optically identifying galaxies associated with the radio emission. Due to the relatively high flux density limit imposed, the cluster radio sources in this sample are among the most powerful in the southern sky. The probability of a cluster containing a radio source of this power is found not to depend on cluster richness.

Various authors have reported observations of the flux and circular polarization for the three stars PG 1658 + 441, PG 1533 − 057 and K 813 − 14. On the basis of the observational data, the stars were classified as magnetic white dwarfs. To place constraints on the magnetic field strengths and geometries of these stars, the relevant authors qualitatively compared the data with available theory and, in two cases, used a model of optically thin hydrogen threaded by a magnetic field.

In this paper we use a more detailed model for magnetic white dwarfs to assess the results previously obtained for these three stars. We find that, in two cases, the observed spectra can be explained by the Zeeman splitting of hydrogen lines in a stellar magnetic field which takes the form of a dipole situated at the centre of the star. The circular polarization data for PG 1658 + 441, however, may indicate a field geometry for this star which is significally different from that of a centred dipole.

As part of an identification programme undertaken on the southern section of the Molonglo Deep Sky Survey of Radio Sources, the limiting magnitudes of some of the available ESO-B films and SRC-J films and plates in this area have been determined. The Molonglo Deep Sky Survey has been described by Robertson (1977). The southern section comprises a 45’ wide strip centred about declination -62° and stretching in an irregular fashion from 18h 25m to 00h 16m.

The space density of degenerate stars is an important parameter in Galactic Structure studies, not only because white dwarfs represent a significant fraction of the local mass density, but also because they act as tracers of the history of star formation (see e.g., Bessell 1978). Combining the present day luminosity function with theoretical cooling tracks allows constraints to be set on the birth rate of main sequence progenitors. However, since white dwarfs are intrinsically low luminosity objects, observational studies are hampered by difficulties in defining complete samples large enough to have statistical significance. This paper discusses preliminary results from one method of tackling this problem.

A typical stellar spectrogram shows a vast number of spectral lines. Each of these has its characteristic shape and strength which must, in some way, reflect the structure of the atmosphere in which the radiation arose. It seems reasonable that from all this profile data we should be able (and with considerable redundancy) to infer a good deal about the physical structure of the radiating gas, and a major effort has correspondingly been devoted to clarifying the physical basis of spectral line formation, i.e., exactly how the atmospheric structure and the atomic properties are reflected in the line profiles. This problem, however, is far from solved : Few, if any, of the profiles of strong lines can be predicted in detail from model atmospheres, nor have analyses of the profiles yielded unambiguous data on the atmospheric structure. Indeed, as recently as 1967, the participants at a conference in Bilderberg (Holland) concluded that no data at all which had been obtained from line profile analyses was worthy of inclusion in specifying the solar atmospheric model. Evidently, then, the problem of line formation is not trivial ; in this paper we discuss some of the difficulties and review the not inconsiderable progress which has been made in this area of astrophysical research.

A sample of 339 extragalactic radio sources, noted as extended or multiple in the Molonglo Reference Catalogue, has been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. It is found that the strong sources all have edge-brightened morphology, while weak sources may be edge-brightened or edge-darkened. The morphological classification of Fanaroff and Riley is not a sharp division by luminosity. The degree of edge-darkening or edge-brightening is better parametrised by one-dimensional moments along the major axis than by the ratio of the separation between brightness maxima to the total extent as used by FR.

I shall outline the physical principles on which I believe pulsar magnetosphere models should be based. The principles follow from the equations of continuity and motion for each species and the two sourceless members of Maxwell’s set of equations, together with the steady-rotation constraint and boundary conditions at the stellar surface.

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.

The present knowledge of atomic spectra is quite impressive but is far from satisfying all needs in fields such as astronomy. The first and second spectra of many elements have been analysed into energy levels but the spectra of the rare earths and many highly ionized atoms are largely unexplored. However the spectra of Fe I, II and III are now fairly well analysed.

The Teff (effective temperature) scale for M dwarfs is very uncertain. One method which can be used to establish this scale is to compare observed spectra to synthetic ones derived from appropriate model atmospheres. With this method the adequacy of the model atmosphere is of great importance and simple models can give incorrect results. Alternatively if the Teff scale is known with some accuracy then this comparison is a good test of the adequacy of the models. We have computed some new and preliminary model atmospheres for late type dwarfs which accurately treat the line opacity with the opacity sampling technique and employ laboratory values for the transition strengths of molecular bands. With the above two considerations in mind we compare the fluxes of these models to observed fluxes of late K and early M dwarfs. This preliminary analysis indicates a discrepancy with the currently accepted Teff scale for early M dwarfs with the models suggesting values some 200 K hotter.

The Corona Australis cometary globule is a large southern object known to be a region of slow star formation. We have mapped the complex in the 21cm hydrogen line and preliminary results are reported in Llewellyn et al. (1981) and Taylor et al. (1981). The most extensive A, map of the region is given by Rossano (1978) and is based on star counts.

At previous meetings of the A.S.A., brief reports have been made of a new theory for the formation of the solar system which is being developed at Monash University (Prentice 1972, 1977, 1978a, b; Hourigan 1977). This work is nearing completion and on this occasion an outline of the whole theory is presented.

From 1951 to December 1964 the Radiophysics Division of CSIRO regularly operated a solar radiospectrograph at Dapto, N.S.W. This instrument finally spanned the frequency range from 5-2000 MHz with 8 separate receivers, 6 of which used mechanical tuning. Simple rhombic aerials were used on all bands except the 200-2000 MHz band which used a parabolic reflector. The quiet sun could be detected on the latter band only.

During 1965 a section of this spectrograph covering the frequency bands from 10-210 MHz was moved to the CSIRO Solar Observatory, Culgoora, N.S.W., and operated as an interim measure to maintain continuity of observations during the installation of the 80 MHz radioheliograph.

In this contribution, which is an expanded version of an invited lecture at the 1982 A.G.M. at Noosa Heads, the author recalls some of the early work in radio astronomy from Dover Heights.

Crannell et al. (1978) have reported an observed correlation between the time profiles and flux densities of impulsive hard X-ray and microwave solar bursts. We report here on a significant correlation between the flux density of extended bursts of hard X-rays and micowaves. These extended events follow after impulsive bursts and last much longer (see e.g. Fig. 1, Frost and Dennis 1971). However, as extended bursts only occur during very large flares the number of cases available for study is small. The significance of our observations follows from the suggestion of Wild et al. (1963) that the extended bursts are evidence for a second-phase acceleration process in the corona. We show that the observed characteristics of these extended microwave bursts (viz. a rather flat spectrum below a turnover frequency which is independent of intensity) can be explained by gyro-synchrotron radiation from the same population of energetic (E ≈ 100 keV) electrons as those emitting (thin-target) X-ray bremsstrahlung. A detailed source model is discussed in a companion paper (Nelson and Stewart 1979 — Paper B).