The LYMAN project has been the subject of industrial Phase A studies in both Australia, and within ESA. These studies have demonstrated an extremely useful international collaboration, as well as a very successful collaboration between University and Industry. Working together, we have identified all critical problems of feasibility, and have developed at least one, usually more than one, method of overcoming these while remaining within the cost and complexity envelope of the overall mission.

The LYMAN mission will be the subject of a competitive selection process within ESA at the end of November 1988. One of five projects will be selected to go forward into later phases. However, the Australian LSWG are confident that, with the enormous support that the LYMAN project commands on both sides of the Atlantic, with the tremendous scientific merit of the proposed mission, and with the demonstration of feasibility of the mission in two separate Phase A studies, that LYMAN will be the successful candidate.

A proposal for the siting of additional 14 metre antennas for the Fleurs Synthesis Telescope (FST) was previously presented by Christiansen (1976). Since that time, difficulties have arisen which preclude the use of two of the locations. In addition, solutions to the problems of data reduction for irregular antenna spacings have been found (Frater and Skellern, 1978; Frater, 1978; Frater, 1979). It has now been possible to choose the locations of the final antennas to optimise the performance of the array within broader geographic constraints — subject now to the availability of sites on ‘friendly’ land.

Since the Molonglo cross-type radio telescope was completed in 1967 July, a considerable proportion of the observing time has been taken with calibrating the pointing of the north-south arm. In a current programme the aim is to obtain accurate positions for sources contained in the flux density catalogue recently prepared by Wyllie. This will provide a uniform set of several hundred positions and flux density calibrators covering the +20° to −90° declination range observable at the Molonglo Observatory.

Young supernova remnants are poorly understood and few are known. Further examples may be present, but unrecognised, within existing catalogues of radio sources. G274.68–2.84 was recently suggested as one such candidate but our new radio map from the Australia Telescope indicates that it is not a supernova remnant. Rather, it appears to be extragalactic with a strong, variable, flat-spectrum nucleus, and a bright X-ray counterpart.

The possibility is considered that core emission in pulsars results from secondary e± pairs generated through linear acceleration emission (LAE), rather than the conventional curvature emission (CE). It is found that this is possible in principle, but only under conditions that appear not to be satisfied in practice.

The reappearance of radio emission from SN 1987A is discussed. We propose a model involving synchrotron radiation from electrons which are accelerated when the expanding supernova shock wave runs into a density jump in the circumstellar material, and which then expand adiabatically.

In designing a stellar spectrograph, it is pointless to exceed the resolving power necessary to obtain all the information from the spectrum of a star. This is limited mainly by atomic thermal motions, giving rise to the Doppler broadening of spectral lines, by turbulence and rotation of the stellar atmospheres in which the lines are formed, and by collisional broadening.

Line absorption associated with the 12.2 GHz 20 − 3-1 transition of CH3OH has been mapped towards Sgr A with the Parkes 64-m radio telescope and a 2 arcmin beam. Two concentrations are present, both offset from the continuum peak, with velocities of 18 and 46 km s-1 and line-to-continuum ratios of 0.59 and 0.30. For the higher ratio the column density is almost 1017 cm-2. The concentrations may be associated with a molecular cloud which overlies Sgr A East but lies in part behind Sgr A West.

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.

A nearly stationary pulsar wind is shown to be always collimating along the direction of rotation. It follows that the conventional picture of the equatorial pulsar wind can occur only in a highly time-dependent manner, which, if true, may account for the observed time variation within a single pulse. Furthermore, a mechanism, via excitation of magnetosolitons, is proposed for explaining the continuous generation of energetic electrons, which yield the observed radio emission in the Type II supernova remnants. Fully relativistic analyses will be presented to substantiate these claims.

The nature and cause of the double-mode (DM) pulsation in beat Cepheid variable stars is still a matter of considerable uncertainty. Recently, evidence has been accumulating that the relative energy of the two modes in any particular star may be a slowly varying function of time. For TU Cas, Hodson, Stellingwerf and Cox (1979) have found that the first overtone amplitude has been decreasing over a 67 year timebase, while the present authors (Faulkner and Shobbrook 1979) have reported an increase in overtone energy in U TrA over 20 years. Observational details of the form of the mode energy changes may be helpful in obtaining a better understanding of these stars (see Shobbrook and Faulkner 1982). Our present observations of U TrA have been obtained to investigate its energy changes more fully.

It is possible to detect gravitationally-lensed quasars spectroscopically if the spectra obtained during galaxy surveys are searched for the presence of quasar emission lines. The up-coming 6 degree Field (6dF) redshift survey on the United Kingdom Schmidt Telescope will involve obtaining ~105 spectra of near-infrared selected galaxies to a magnitude limit of K = 13. Applying previously developed techniques implies that at least one lens should be discovered in the 6dF survey, but that as many as ten could be found if quasars typically have BJ – K ~ 8. In this model there could be up to fifty lensed quasars in the sample, but most of them could only be detected by infrared spectroscopy.

We have constructed theoretical spherical dust shell models using a full radiative transfer treatment, to investigate the effect of thermal emission on the strengths of molecular CO and H2O features in late type stars with circumstellar dust shells and to establish the optical depth at which the strengths of the bands are significantly affected. In this study, for the first time the central sources have been represented by realistic atmospheric models for cool stars in the temperature range 2500–3000 K, which are representative of the central stars of OH/IR sources. Parameters of the dust shell models were chosen to fit the observed run of colours from 1.25–5 μm of a large sample of OH/IR sources using ‘dirty silicate opacities’. The results show that the molecular band strengths in the 2 μm region are significantly affected by the dust emission only when the optical depth in the shell reaches a value of τ1μm ≈2 for T* = 2500 K and somewhat less for T* = 3000 K. However, the changes are such that the distinction between supergiant-like spectra, and variable M-star spectra is retained in models with very high shell optical depths. The implications of these models are discussed in relation to previous observations of OH/IR sources.

It is widely believed that stars form from collapsing interstellar clouds. However, molecular clouds typically contain of the order of 103 solar masses. Thus a mechanism is required that allows a collapsing cloud to fragment into a number of collapsing stellar sized sub-condensations. The early work was based on a virial theorem approach—defining a critical mass a cloud must exceed in order for its gravitational force to overcome the resistive thermal, rotational and magnetic forces, thus allowing the cloud to collapse. This critical mass is analogous to the Jeans mass for non-rotating, non-magnetic clouds. It is thought that a cloud containing several critical masses may collapse into several sub-condensations. Further, it is thought that the galactic magnetic field will cause the critical mass to decrease as the cloud collapses, allowing the cloud to fragment into a number of sub-condensations. The critical mass decreases as the cloud flattens down the field lines (since Mcrit ∝ B3/ϱ2 and B ∝ ϱk, K < ⅔ for non-isotropic collapse).

A K-band (18-25 GHz) reflected-wave ruby maser (Moore and Clauss 1979) has been borrowed from the National Radio Astronomy Observatory for radio astronomy use on the NASA 64-m antenna of the Deep Space Network at the Tidbinbilla Tracking Station, near Canberra. The purpose of the installation is to provide additional sensitive spectral line, continuum, and VLBI capabilities in the southern hemisphere. Previous measurements at 22.3 GHz (λ = 13.5 mm) determined that the Tidbinbilla 64-m antenna has a peak aperture efficiency of ˜22%, a well-behaved beam shape and consistent pointing (Fourikis and Jauncey 1979). Before installing the maser on the antenna a cooled (circulator) switch was added to provide a beam-switching capability, and a spectral line receiver following the maser was incorporated. The system was assembled and tested at JPL in late 1980 and installed at Tidbinbilla early in 1981. We give here a brief description and present some of the first line observations made in February and March 1981. Extensive line and continuum observations are planned with the present system and a program is under way to determine the telescope pointing characteristics.

Recent evidence suggests that radial pulsation can explain most of the variability in the majority of well-studied β Cephei stars (Stamford and Watson 1978; Campos and Smith 1980).

A graphical format has been adopted to depict some characteristic variations associated with the solar activity cycle up to 1988, for both the Zurich annual and monthly mean values over the respective periods from 1700 and 1750. Both low pass and band pass filtering techniques have been employed to smooth the data, the autocorrelation coefficients determined for a high number of lags to illustrate the secular modulation of the maximum values in each cycle and the spectral amplitudes computed to establish periodicities in the chronologies.