For many years now, large plastic scintillator and geiger counter muon telescope systems have been used underground for studies of the small variations of the cosmic ray particle intensity that occur at primary energies around 1011 – 1012 eV. Although long-term deterioration in telescope counting efficiency is liable to take place it has been possible to take care of it sufficiently well to allow accurate observations to be made of the important daily variation and of transient events such as the Forbush Decrease and the solar flare increase.

Of the attempts to model the Magellanic system as the result of tidal interactions, only the works of Lin and Lynden-Bell (LLB 1982) and Murai and Fujimoto (MF 1981) can be considered to be successful.

Despite its superb optical and radio observatories, Australia is essentially blind to the entire submillimeter and far-infrared spectrum. The importance of this spectral region can perhaps best be illustrated by reference to Figure 1, which shows the flux of the galaxy NGC253 as a function of frequency.

A consortium of Australian universities and the Anglo-Australian Observatory is currently implementing an adaptive optical system at the Anglo-Australian Telescope. This project aims to enhance the science output of the telescope and establish the utility of adaptive optics at the AAT site. The first stage of the project is a fast tip-tilt system, described here, to be installed in the west coudé room. Subsequent funding has been obtained to implement a second-stage, low-order deformable mirror system which is also outlined. Both phases will primarily serve the IRIS camera/spectrograph, since the maximum gains in image quality will occur in the infrared.

In the wide complex profiles of OH, H2CO and CO spectra observed in directions towards the galactic centre, only the features at radial velocities near + 40 km s-1 are generally believed to originate in the molecular clouds nearest the galactic nucleus. The features at other velocities are associated with clouds or spiral features that can be traced over larger ranges of galactic longitude, implying locations which are more distant from the nucleus. In particular, the features near zero velocity have been traditionally associated with molecular clouds within 1-2 kpc of the Sun. However, H2CO observations with high velocity resolution provide evidence that one cloud with velocity near zero is probably near the galactic nucleus.

Work is in progress on the extension of a detailed stellar structure code to explore a suggested solution to the Solar Neutrino Problem where the Sun has a small (∼0.01M⊙) high-Z core on entry to the ZAMS. A basic premise of such models is that the core will burn itself out by solar age and the model acquire a neutrino luminosity in line with that observed. The work to date has involved the construction of a standard solar model and, currently, the development of inhomogeneous models with associated adjustments to the structure equations.

On 1973 March 22 a radio event was observed above the east limb of the Sun with the Culgoora radioheliograph operating at both 80 and 160 MHz. The first stage of this event, a type I storm closely associated with a rising prominence, offers a new insight into the nature of this phenomenon. This storm was followed immediately by a moving type IV burst – the first burst of this kind for which two-dimensional observations are available at two frequencies. The relation between these two stages may help explain the ‘missing hour’ in observations of another moving type IV burst known as ‘Westward Ho’.

The darkness of sunspots has been attributed by many authors (Biermann 1941; Danielson 1961) to the inhibition of the normal solar convective processes by the presence of strong magnetic fields. Observations of the solar photospheric granulation pattern have also shown that a weak longitudinal field exists outside the activity regions. Although these observations have not revealed any close association between the magnetic field and individual granules, nor the exact reasons for the darker cell boundaries, it must be accepted that, overall, the role of the magnetic field must be such as to influence the cell structure and reduce the normal heat transfer by convection.

A combined multi-station radar equipment of c.w. and pulse at 27 MHz was used at Adelaide (lat. 35°S) during the period December 1968 to June 1969 and again in October 1969 to measure radiants and velocities of individual meteors down to limiting radio magnitude MR = + 8. Reflections from 3 to 5 points typically separated by 2 to 6 km along each trail were used and corrections for the effects of meteor region winds and wind shears were included. To date 1667 orbits have been determined from 6 months of data.

In an attempt to determine whether the lithium Une at 6707 Å cornes mainly from the quiet photosphere or from the cooler spots on spotted active stars we have measured Une équivalent widths due to Li and also due to Cal at 6717 Å at various rotation phases on three fast rotating stars, AB Doradus, PZ Telescopium and V 1005 Orionis. The results for AB Dor and PZ Tel show there might be some small rotational modulation which can be linked to the best estimate of the spot position from the available photometry. This moduation is less than that expected on the basis of Giampapa’s work on sunspot spectra. The Li and Cal line equivalent widths were found to anticorrelate.

We present near-infrared images and spectra of the peculiar radio galaxy Centaurus A. The images reveal extended emission regions at the longer wavelengths and show colours characteristic of reddened starlight. We believe we are seeing stars within the warped disc of Cen A, which are obscured in the optical by dust. Both images and spectra indicate the presence of a compact core, whose colours are much redder than those of the surrounding stars. In the spectrum of the core, detections have been made of [Fe II] 1.644 μm, H2 2.122 μm and Br γ. These lines appear to peak on the nucleus and their presence and width suggest starburst activity.

Most plates taken with the UK Schmidt Telescope are hypersensitized before use. The technique for the hyper-sensitization of IIIa-type emulsions has been described by Sim et al. (1976), and for the IV-N emulsion by Hartley and Tritton (1979). Photographic calibration is provided by two sensitometers, a seven-step linear array at the N-W corner and a 4 × 4 spot array in the S-E. During the calibration of this latter sensitometer (Dawe and Metcalfe 1981), which is a copy of a design by Schoening (1976), it became apparent that the sensitivity of the hypersensitized IIIa-emulsions in use was decreasing as a function of time in the plateholder.

This conference has shown that the accumulated wealth of data on SN 1987A has enabled us to learn an unprecedented amount of physical information about a single supernova event and supernovae in general, as well as to confirm much of the heretofore established theory. While some difficult problems remain, I discuss some particularly simple and useful theoretical notions concerning the bolometric and γ-ray light curves which can be gleaned from our current body of knowledge, drawing primarily upon results of analytic work performed by W.D. Arnett and myself. Also, the work of Lamb, Melia and Loredo (1987) on neutrinos from the supernova is discussed briefly.

The eighth magnitude star HD 101065 is an extremely peculiar star with a unique spectrum characterized by numerous strong lines of the rare earths and the absence, or at least a remarkable weakening, of the lines of the iron group (Cowley et al. 1977). Besides the lanthanides only yttrium, zirconium, calcium and barium are definitely present in the atmosphere in substantial quantities. The evidence for the presence of lithium and strontium is subject to some doubt since these elements are represented only by one or two reasonably strong lines, which is insufficient for a positive identification in a spectrum as complex as that of HD 101065. The evidence for the presence of other elements is the subject of a critical examination in a recent paper by Cowley et al. (1977). The effective temperature of the star is about 6100 K (Przybylski, 1977) which is substantially lower than the temperature of any known Ap star. However, the effective temperature of HD 101065 is still subject to controversy (Wegner, 1976).

Sites of recent star formation often radiate strong maser emission from methanol transitions near 6-6 and 12 GHz. We have studied many of these masers over several years and find that intensity variations are common on both transitions. We present observations which demonstrate marked variability in 48 sources. We explore the characteristics of the variability and find it to be typically quasi-periodic, on a timescale of between a month and several years. The amplitude of the variation is most commonly less than a factor of two, but can reach factors of ten. The variability of different features in a source is usually independent. Variability of features seen at both 6·6 and 12 GHz is sometimes correlated, with larger amplitudes usually seen at 12 GHz. A likely inference is that variations are occasionally due to a change in the pump rate throughout the masing region, but most are consistent with a change in the masing path length due to large-scale motions. In addition, it is likely that the majority of 6·6-GHz masers are saturated whereas the 12-GHz masers may be somewhat less saturated.

The structure of small diameter radio sources can be investigated by studying the scintillation of the source due to the interplanetary medium when the line of sight approaches the Sun. Observations of radio source scintillation are currently being undertaken with the separate arms of the 1 mile radio telescope at the Molonglo Observatory. The EW arm allows successive transit observations with three fan beams, 1′.4 EW by 4°.2 NS at 408 MHz, bandwidth 2.5 MHz. Sources transit the half-power points of each beam in 6 sec δ seconds of time (δ is the source declination). The NS arm gives eleven fan beams at neighbouring declination, 1′.5 sec Z NS by 4° EW (Z is the zenith angle). Complete transit of a NS beam takes 15 sec δ minutes.

In the preceding paper, observations of the coronal broadening of the Crab Nebula during 1969-71 were described. The basic parameters, radial and tangential broadening, and their relation to previous work were discussed. Whereas previous observations have utilized two or three interferometers only, so that the degree of broadening along any particular axis could only be obtained under the assumption of a particular form (e.g. Gaussian) for the angular power spectrum, the present work has enabled complete sampling of the two-dimensional brightness distribution of the broadened source. It is therefore possible, and of considerable interest, to compare the observed distributions to those computed on the basis of various theoretical models for the scattering process.

Observations of the galactic background radio emission at a number of frequencies between 2.7 MHz and 1.07 MHz were made in association with the plasma depletion experiments of Spacelab-2 to test the concept of making low frequency radio observations through an artificial ionospheric window. Following the Shuttle OMS burn at a time when foF2 was 1.99 MHz, a decrease in the maximum ionospheric electron density of approximately 30% occurred. The first observations of the radio emission at high galactic latitudes with good angular resolution (25 degrees) were obtained during this event.