High resolution studies of clusters of galaxies at radio frequencies may contribute substantially to our knowledge of the properties of radio galaxies, their evolution and their luminosity function. A considerable amount of statistical information is already available on the correspondence of radio sources and clusters; the present investigation is aimed rather at a detailed examination of the sources and their identification with actual galaxies or other objects.

Radio maps of extragalactic radio sources made with the Westerbork, Cambridge and V.L.A. synthesis telescopes have revealed collimated jets extending from the cores to the radio lobes (see Miley 1980 for a review). These observations have provided outstanding support for ‘beam models’ of extragalactic radio sources (Scheuer 1974, Blandford and Rees 1974). Two crucial pieces of information to emerge from high resolution observations are the behaviours of jet full width half maximum (FWHM) and surface brightness with angular distance from the core. Such data have for instance been provided by Formalont et al. (1980) and Bridle et al. (1981) for the jets in 3C-31 and by Willis et al. (1981) and Bridle (1981) for the jets in NGC 315. An important point is that the relationship between jet surface brightness and FWHM is not in general as predicted by simple magnetohydrodynamic models (Bridle 1981).

The variable X-ray source in the direction of the Small Magellanic Cloud (SMC), SMC X-1 (2U 0115-73) was discovered by Leong et al. (1971). X-ray eclipses with a period of 3.8927 ± 0.0010 days were subsequently reported by Schreier et al. (1972). Identification of the X-ray source with SK 160, star number 160 in the list of Sanduleak (1968), was proposed by Webster et al. (1972) on the basis of the similarity of its spectrum with that of the optical counterpart of Cyg X-1.

The third Uhuru catalogue of X-ray sources (Giacconi et al. 1974) contains X-ray source positions given to a much higher precision than was previously available and this fact has given considerable impetus to the search for optical and radio counterparts. Many such identifications have now been made and confirmed, e.g. by discoveries of correlated variability.

Daily rainfall data for Sydney, Prague and Moscow for singularities around 26 May and 9 November were examined by an autocorrelation method. Intervals between 2 and 7 days were used for the autocorrelation. In all three samples the wider the interval used the later the date of the best autocorrelation. The shift is discussed from the point of view of the Bowen hypothesis on meteor-rainfall correlation. Also new results supporting the Bowen hypothesis and its new version on bacteria from space, published recently, are briefly discussed.

On 17 June 1968 we observed a flare event with the 80 MHz Culgoora radioheliograph consisting of a sequence of two type II bursts followed by enhanced emission possibly of type IV. In this paper we shall attempt to summarize some ofthe profuse data collected by the radioheliograph during this event and relate it to data from the radiospectrograph and Hα films of the associated flare (the Hα films were kindly made available by the Division of Physics, CSIRO).

Based on a new sample of (IRAS based) OH/IR stars, and a catalogue of planetary nebulae compiled by Acker (1983), we study the relation between these two groups of objects, in terms of the kinematics and the Galactic distribution. In contrast with earlier analyses of samples of OH/IR stars, we find a close correlation between the kinematics of the planetary nebulae and the IRAS based sample of OH/IR stars. In particular, we find that the distribution of the planetary nebulae (PN) shows a good correlation with the OH/IR stars which have a low outflow velocity (Vexp < 12.5 km s−1). Whether the high outflow velocity OH/IR stars also have a counterpart among PN is not clear.

The subject of extraterrestrial civilizations is relevant to astronomy in two ways. Firstly, the very existence of life outside Earth is dependent upon the picture that astronomers can draw of the Universe, and we will see how that picture allows us to be very optimistic. Then, if we think that there are intelligent beings in space, the detection of signals from them is an astronomical problem, and we will see that it most probably concerns radio astronomers.

A particle method for the simulation of the global evolution of cold gas in galactic potentials is described. It incorporates an efficient artificial viscosity, based on the smoothed particle hydrodynamics approach, which conserves both linear and angular momenta and in the continuum limit is equivalent to a Navier-Stokes viscosity in a compressible gas. Parameters of this viscosity have been calibrated in such a way as to make a gas disk, embedded in an axisymmetric galactic potential and originally inclined to its equatorial plane, settle to the preferred plane on the time scale characterizing the differential precession. After a careful analysis of the previously published settling times we find that our results are consistent with Steiman-Cameron’s (1984) lower limits, and we argue that Simonson’s (1982) time scales have been seriously underestimated. We also demonstrate that two dimensional methods based on rigid rings do not model the evolution of a differentially precessing settling gas disk realistically and cannot be used to study the morphology of gas distribution.

Propagation of 150 μs radio pulses (f= 1.91 MHz) along a magnetospheric field-aligned ionization duct have been observed, under conditions of low ionospheric critical frequency. The echoes, presumably reflected from the ionosphere at the magnetic conjugate point, were received at the transmitting site near Hobart. Positively identified echoes were observed on six separate occasions during periods of moderate solar activity, with delay times of approximately 260 ms, representing a value L = 2.95.

We propose to construct an optical interferometer to produce high resolution images by aperture synthesis. The interferometer, known as the Masked Aperture Pupil-Plane Interference Telescope (MAPPIT), will be mounted at the coudé focus of the Anglo-Australian Telescope. It will use a non-redundant aperture mask, together with closure phase methods developed for radio VLBI, to overcome the wavefront distortions which are introduced by atmospheric turbulence. By using the techniques of pupil-plane interferometry and wavelength dispersion, it is hoped that MAPPIT will have more sensitivity than many other interferometric imaging projects.

A few days ago a prominent physicist, Professor Frank Stacey of the University of Queensland, made a public statement on his retirement that he was burying a theory. He had believed he had measured a new gravitational constant for close objects. Over 12 years he and colleagues in Australia and overseas had tried to confirm a theory of a fifth fundamental force of nature to explain the observations. His claim had gained a great deal of publicity as, if true, it would have extended Newton’s law of gravity and Einstein’s theory of general relativity.

Infrared spectroscopy is a relatively new field in astronomy. When the study of celestial sources at wavelengths longer than 1 μm underwent a major spurt of growth in the mid-sixties, it was natural for astronomers to concentrate on broad band measurements. As detectors and instrumentation have steadily improved and the broad band characteristics of stellar sources in the IR have become better known, there has been a natural trend to higher spectral resolution. To date there has been sufficient work in IR spectroscopy to warrant several reviews on the subject. Although Australia has been late in entering this exciting and expanding field, the quality of work has more than made up for the delay. In this review I will briefly describe several projects involving IR spectra performed in Australia. Special emphasis will be placed on those experiments that cannot be done by any means other than IR spectroscopy. Also presented is a description of Australia’s next generation of spectroscopic instrumentation for the IR.

The function of the 158 MHz interferometer operating at the CSIRO Solar Observatory, Culgoora, N.S.W., is the measurement of solar radio burst positions at a frequency close to the second harmonic frequency of the radioheliograph. The interferometer is designed to measure the north-south and east-west position co-ordinates of an isolated active region on the Sun with an accuracy of ~1′ arc, at rates up to 16 s−1.

One of the unusual features of the lenticular galaxy NGC 5128 is the presence of HI absorption (Roberts 1970; Whiteoak and Gardner 1971) and H2CO absorption (Gardner and Whiteoak 1976) against the radio source located near the nucleus. Using the Parkes 64-m radio telescope we have made HI and H2CO observations with improved resolution, and have also detected OH absorption in this galaxy. For the OH and H2CO observations, the equipment and observing procedure have already been described (e.g. Whiteoak and Gardner 1973; Gardner and Whiteoak 1976); for the HI observations they will be described in a forthcoming paper (Whiteoak and Gardner, to be submitted to Aust. J. Phys.).

We present high-resolution absorption measurements (R ~ 150 000) of the interstellar Na I D-lines at 5890 Å observed towards 46 early-type stars. The distance to these stars ranges from 20–200 pc, allowing a probe of the local interstellar medium (LISM). The velocity structure, velocity dispersions and column densities of the various cloud components have been derived using an absorption line-fitting analysis. Sodium column densities have been determined for 23 of the 46 target stars. No sodium absorption was detected towards any of the stars with distances < 43 pc. Such null results imply a corresponding hydrogen column density limit, N(H), of ~ 2.5 × 1018cm−2 in many directions in the LISM. For three exceptionally vacant lines of sight (to β CMa, 36 Lyn and η Hya) this limit of low hydrogen column density can be placed out to a much further distance of > 150 pc.

We have plotted the distribution of sodium column density in the LISM for a total of 118 stars in the form of three galactic maps. These maps qualitatively show that the present picture of the LISM, in which the first 50 pc is essentially free of dense clumps of neutral gas, is correct. Our map of sodium columns for stars with distances > 100 pc shows that the region within the galactic quadrant defined by 200° < l < 270° shows a conspicuous absence of any significant concentration of neutral gas. This region will be a prime direction of study for forthcoming soft X-ray and extreme ultraviolet satellite experiments.