Current results from the experiment by Reines et al (1980) on the oscillation of neutrinos from one flavour to another, if confirmed, require a non-zero rest-mass for the neutrino. Corroborative evidence can be adduced from the astrophysical consequences. In particular, the long-standing ‘missing light’ paradox in rich clusters of galaxies is solved (c.f. Cowsik and McClelland 1973), and more recent difficulties in reconciling the chronology of the Universe with both the primordial abundance of He4 and the cosmological mass density are eased (c.f. Symbalisty et al 1980). Finally Lewis (1981) shows that the concept also solves the problem of obtaining dynamically relaxed clusters of galaxies with feasable formation times. As a result, elliptical galaxies are necessarily formed from the material of a proto-cluster amid a high density of low-velocity neutrinos. This paper makes a preliminary estimate of the maximum neutrino content of elliptical galaxies.

Mount Stromlo Observatory came into being on 1 January 1924. First known as the Commonwealth Solar Observatory, it was founded primarily for studying the Sun and solar-terrestrial relations, though from the outset it was much concerned with various aspects of geophysics. There was also a stellar programme, but after a promising start this had to be discontinued. The solar-geophysical regime continued, with success, until World War II. The Observatory went through the War with a new director, and at the end of it embarked on a new and unfamiliar course to develop into the fully-fledged astrophysical institute it has become today. This transition marks an important chapter in the history of Australian astronomy: I have tried here to describe some of its aspects, as they seemed to me.

A version of this paper was originally presented at the Fifth National Space Engineering Symposium at Canberra in November 1989. A copy of the full paper will be found in the text of the Proceedings. It is presented here because the authors believe that the issues raised and strategies suggested are as relevant to the astronomical community as they are to other areas of space science and technology.

Properties of the microwave emission from HR1099 are examined in an attempt to determine whether the emission arises as gyro-synchrotron radiation from mildly relativistic electrons trapped in magnetic fields above starspots on the active K subgiant component. It is shown that radio curves do not exhibit a systematic variation in phase with the rotation rate, as one might expect for emission from a source situated above a long-lived starspot. However, there is some evidence that the radio flaring occurs at two preferred longitude zones. Whether these zones agree with starspot locations remains to be determined by light curve modelling. What we can say with confidence is that the measured spectral index of the microwave emission does not fit a simple gyro-synchrotron source model, such as that proposed to explain the observed reversal with frequency of the sense of circular polarization.

For a number of years the occurrence of isolated groups of apparently related type III bursts has been recognized as a common feature of the dynamic spectral records of solar radio emission at metre wavelengths. Interferometer observations supported the simple hypothesis that bursts of a group were usually located in the same position. In this note we report 80 MHz observations made with the Culgoora radioheliograph which show that although the sources of the bursts in a group tend to overlap one another, their centroids may show marked scatter and that their distribution tends to be along narrow lanes across the solar disk. Since the 80 MHz sources occur at heights (≳ 0.6 R⊙) near or above the plasma level, these lanes doubtless reflect some structural feature of the outer corona.

We summarise the results, to date, of a long-term program of searching for flare stars in the region of open clusters selected on the basis of distance and age.

Correlation radiotelescopes have become increasingly important in the last few years in all types of astronomical observations. These instruments operate by multiplying (correlating) the outputs of two separate aerials in order to provide a composite antenna with a range of aerial spacings and orientations. As a general rule this range of spacings is truncated at both the largest and smallest spacings, the largest spacing being determined by the area available or by the cost of the system, and the lowest spacing by either cross coupling between the multiplying elements (as in the Mills Cross type) or by the geometrical size of the elements (as in the compound interferometer type).

strong non-thermal radio sources at low galactic latitude may be young galactic supernova remnants or else distant extragalactic objects located in the direction of the galactic plane merely by chance. Here, we have imaged G321.48 + 1.02 with the Australia Telescope in order to distinguish between these alternatives for this source.

SN 1987A has been observed with a combined high energy γ-ray (50-500 MeV) and hard X-ray (15-150 keV) payload during a balloon flight on 5 April 1988 from Alice Springs, Australia. The γ-ray observations, along with our earlier ones on 19 April 1987 are the only such observations of the supernova to date. The γ-ray detector characteristics are described. The preliminary results of the recent flight and their implications in terms of the known supernova parameters are discussed.

The reason why some early-type galaxies contain powerful radio sources is not yet well understood, but it is often suggested that an external factor such as interaction with a neighbouring galaxy may be involved in triggering a radio source (Gisler 1976, Dressel 1981, Hummel 1981b). Radio emission may be enhanced in galaxies which have a close companion for several reasons, such as a gravitational perturbation or the possibility of gas accreted from the companion fuelling a central source. The latter effect might be expected to be more pronounced in elliptical galaxies, which are generally gas-poor (Faber and Gallagher 1976).

During the second half of 1986 tests were made of a new Q-band (43 GHz) receiver designed for the Parkes radio telescope. As part of the trial observation program 12 symbiotic stars were examined for SiO maser emission. No significant new emission was detected from any of the candidates, although several previously known SiO sources (including one symbiotic star) were confirmed. We conclude that potential SiO maser action near the Mira star in most symbiotic systems is prevented by the presence of the hot companion star.

In the five years since the last invited paper on model stellar atmosphere applications there have been many significant advances made on all fronts. The five aspects which I will cover in this paper are:

• (1) the results of white dwarf model atmosphere investigations;

• (2) the results of the inclusion of non LTE phenomena in the atmosphere computations of hot (T > 15,000 K) stars;

• (3) the probable understanding of the cause of peculiar abundance patterns in the Ap and Bp and Am stars;

• (4) the advances in theory and observations of cool star atmospheres; and

• (5) the use of synthetic spectra and colours.

One of the important discoveries of the present century is that the Universe expands. Two important parameters which define the dynamics of the Universe and can be obtained at the telescope are the rate of expansion zhqо , and change of this rate with time qо , It is difficult to derive a value for Hо because accurate distances of farther galaxies are needed. This involves identifying the luminous objects, such as brightest stars, HII regions, globular cluster, supernova etc., in the Local Group galaxies as well as in the external galaxies. Once the absolute magnitudes of these objects are calibrated with the known distances of the Local Group galaxies, distances to the external galaxies can be derived.

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.

For many pulsars the integrated or mean pulse profile is highly polarized. Generally linear polarization dominates over circular and there is a continuous variation of position angle through the profile (e.g. Manchester 1971). In most models for the emission process the angle of polarization is related to the (projected) direction of magnetic fields in the source region. Several of the observed properties of pulsars, for example, the mode-changing phenomenon (Backer 1970) and the different spectral index of different components of the intergrated profile (Manchester 1971), suggest that different parts of the integrated profile are emitted in different (though closely related) parts of the source. The different observed position angles across the integrated profile would then result from different projected magnetic field directions in these different parts of the source. For many pulsars the observed position angle variations are closely represented by a path through a radial set of projected field directions such as would be obtained in the vicinity of a magnetic pole (cf. Radhakrishnan and Cooke 1969).

Over past decades many attempts have been undertaken to detect a statistically significant 11-year variation in tree-ring widths and thereby provide direct evidence for the influence of solar cycle activity on growth. The data were generally associated with arid sites and were found to contain no signal of any consequence at the equivalent frequency. However, our recent analysis of a tree-ring chronology established from spruce trees growing at a very high sub-alpine site in Colorado, has revealed the presence of a dominant 11-year spectral periodicity over the last 200 years. These growth cycles could arise from temperature changes due to variations in insolation and climate or from variations in direct radiation within a specific band.

We report continuum observations of the NGC 7538–IRS 1, 2 and 3 regions made with the NRO 45-metre dish between 43 and 90 GHz, and present a brief interpretation.