Advances in digital computer technology since the middle decades of the twentieth century have transformed many subject areas in astrophysics. Topics which had previously been dealt with by analytic approximations (usually to a very limited number of special cases) suddenly became amenable to detailed numerical modelling for all cases. Frequently, insights derived from this modelling ran ahead of other techniques in predicting physical phenomena before they were either observed or discerned in purely analytic treatments.

It has sometimes been said that the second half of this century has seen the advent of a totally new modus operandi in scientific research, which ranks alongside the two traditional approaches–experimentation and theory. The most powerful computers now available have greatly accelerated these developments. They employ simultaneous computational techniques (either vector processing or parallel processing, or both), and their throughput is so large that, for most problems, the only way in which the human mind can fully appreciate the scientific content of the numerical results being calculated is by transforming those results into pictorial representations.

This paper draws on my experience as Academic Director of the ANU Supercomputer Facility during the first eighteen months of its operation, to describe the place which I believe super-computers will occupy in the development of astrophysics during the 1990s and into the next century.

Radio telescopes in more than 20 different countries on five continents are being used for VLBI observations of galactic and extragalactic radio sources, as well for applications to geodesy and geophysics. New radio telescopes and networks of radio telescopes dedicated to VLBI which are being built in the United States, the U.S.S.R., Italy, China, Poland, the U.K. as well as in Australia will greatly improve the sensitivity, resolution, image quality, and frequency coverage of the existing networks. The Mk II VLBI recording system, which is based on consumer type Video Tape Recorders, is widely used but the sensitivity is limited. Broad band recording systems are expensive, but are becoming more popular due to their much greater sensitivity. They are expected to dominate VLBI systems in the 1990s.

The first tests of an earth-to-space VLBI system took place in 1986, and by the mid 1990s dedicated VLBI antennas will be launched into earth orbit by the U.S.S.R. and by Japan in collaboration with Australia and other countries throughout the world. Space VLBI missions will give an order of magnitude improvement in resolution over the ground based VLBI networks operating at the same wavelengths.

In science we have good, successful laboratories and scientists and we also have wasteful, inefficient and unproductive ones. The differences are not matters of chance.

It is not an accident that just one Cambridge College, Trinity, has achieved more Nobel Prizes than all of Japan. There was something in common amongst the Nobel prize winners Todd, Adrian, Perutz, Bragg, Crick, Ryle, Hewish and Mott that I was fortunate enough to meet and, in some cases, get to know well. Of course there was the personal and intellectual calibre of these people, their drive and determination. But also, there was the laboratory culture within which they worked, a culture still benefiting from the influence of Maxwell, Thomson and Rutherford.

We question Newton’s inverse square law of universal gravitation in the light of recent, alternative formulations. In addition, we present numerical simulations of galaxy interactions which were used in an attempt to distinguish between an inverse square law and an inverse linear law. We conclude that an inverse linear relation is as compatible with the observational data on interacting galaxy systems as the inverse square law.

We present preliminary results from a number of deep radio polarization surveys being made of the Magellanic Clouds at 2.3 GHz, 4.75 GHz and 8.55 GHz. Extended and linearly polarized radio emission has been found at 2.3 and 4.75 GHz from both the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). However, as the analysis of these data is not yet complete we present only some of the 4.75 GHz results at this time.

Recent results have shown that Long-Period Variables (LPVs) with periods in the range 100 to 250 days have ages ~ 10 Gyr. We have studied the kinematics of a sample of such variables in the Large Magellanic Cloud (LMC). A comparison with the kinematics of other populations (H I gas, CO molecular clouds, planetary nebulae, CH stars and old clusters) indicates that all populations younger than the old LPVs are dominated by a single common rotating disk, with the kinematics of the old LPVs being the first to indicate the presence in the LMC of a spheroidal population, with little or no rotation and a velocity dispersion ~ 6 times larger than that of the H I gas.

The most sensitive X-ray survey available is a deep exposure made by the Einstein Observatory of a 40 arcmin field in the southern constellation of Pavo. This survey revealed 33 X-ray sources, most of which were optically identified with quasars. Here, we report radio observations of the Pavo region at 843 MHz made with the Molonglo Observatory Synthesis Telescope. Eight overlapping fields were combined to produce the most sensitive radio map of the region to date, revealing 33 radio sources above a flux density of 2.4 mJy. Only one of these radio sources corresponded to an X-ray object: a quasar at z = 1.13. We also used the Parkes-Tidbinbilla Interferometer, at 2.29 GHz and 8.41 GHz, to observe some of the stronger radio sources.

From these multi-wavelength observations of the Pavo field it is apparent that, to the sensitivity of the surveys involved, (i) there is little correlation between X-ray and radio detections, and (ii) most of the X-ray sources have optical counterparts while few of the radio ones do, and (iii) there is some confirmation that X-ray emission is higher for objects with flat radio spectra (i.e., a dominant core) than for steep spectrum sources.

Large apparent superluminal velocities are observed in nuclear jets in Active Galaxies, indicating the presence of relativistic velocities almost along the line of sight. If the flow is well collimated, as suggested by the large scale radio structure, the inferred alignment leads to difficulties with source statistics. Here a modification of the usual relativistic beam model is proposed, in which the jet is assumed to contain azimuthal (swirling) flow. Perturbation analysis is used to show that the jet is unstable to a Kelvin-Helmholtz helical standing wave, the wavelength of which increases without bound in the limit of vanishing swirl. This instability may cause a cylindrical jet to follow a helical path in space, thereby reducing the implied alignment of a superluminal source, and providing a natural interpretation of non-constant superluminal velocities.

A theory of linear acceleration emission, with possible application to pulsars, is developed. The equation of motion for a relativistic charged particle accelerated in the field of a longitudinal wave is solved to first order in the electric potential and used to derive the first order current. The power emitted and the absorption coefficient are calculated and the conditions under which masing can occur are discussed.

NGC 6302 is one of the highest excitation planetary nebulae known. It has an obscured central star with a temperature estimated at 430,000 K. We present here CCD images in Hα and Hβ of NGC 6302, and interpret the differences between the images as being due to extinction caused by dust within the nebula. The dust appears to be concentrated in the core, as expected from infrared observations. There is no evidence of patchy foreground extinction, although there is a slight difference in the average extinction between the eastern and western lobes of the nebula. A comparison between the Hα image and a 5 GHz map gives a dust extinction of ΔAV~3.5 to the central star. The outer contours of the 5 GHz map are not in good agreement with the optical images, and further observations at this frequency would be useful.

The encounter of the spacecraft Voyager 2 with Neptune and its large satellite Triton in August 1989 will provide a crucial test of ideas regarding the origin and chemical composition of the outer solar system. In this pre-encounter paper we quantify the possibility that Triton is a captured moon which, like Pluto and Charon, originally condensed as a major planetesimal within the gas ring that was shed by the contracting protosolar cloud at Neptune’s orbit. Ideas of supersonic convective turbulence are used to compute the gas pressure, temperature and rate of catalytic synthesis of CH4, CO2 and solid carbon within the protosolar cloud, assuming that all C is initially present as CO. The calculations lead to a unique composition for Triton, Pluto, and Charon: each body consists of, by mass, 18.5% solid CO2 ice, 4% graphite, 0.5% CH4 ice, 29% methanated water ice and 48% anhydrous rock. This mix has a density consistent with that of the Pluto-Charon system and yields a predicted mean density for Triton of 2.20±0.05 g cm−3, for satellite radius equal to 1750 km.

We present a list of bright (< 17 mag) southern QSOs and bright (< 11 mag) stars that may be suitable for the Hubble Space Telescope link between the Hipparcos astrometric reference frame and the VLBI extragalactic frame. The QSOs have been selected from various lists of radio objects and identifications. The stars have been selected from the Strasbourg (CDS) data base and from the Preliminary Second Cape Photographic Catalogue, and supplemented with stars measured from the SERC IIIa-J Schmidt survey. The list of QSOs and stars have been included in the Hipparcos and HST schedule of observations.

This is a brief description of the way I see the Schmidt functioning through the next three years. There are four important functions which must be maintained: (a) The Science from the Schmidt material must continue to be of the same high quality as that on which the Schmidt’s reputation has been built; (b) The service we provide to the Australian and British communities must continue despite the new trim (slim) appearance of the Schmidt staff and budget; (c) We must maintain our links with ROE, its Plate Library, which is the archive for Schmidt plate material, and Photolabs which provide some of the survey atlases; (d) We are being actively encouraged to promote Australian and British usage of the UK’s large measuring machines APM and COSMOS. Additionally, we are continually being encouraged to improve our efficiency. There is still at least one area in which we can do this and this is discussed.

We report on a new method of determining radio source positions with the Parkes radio telescope. The method is appreciably quicker than, but has a comparable accuracy to, established methods such as orthogonal scanning. It has been particularly useful during 1989 in tracking the Voyager II spacecraft as it approaches Neptune; a method of accurately pointing at the source of the radio signal was required without the signal degradation which is introduced by moving appreciably off source.

The University of NSW Automated Patrol Telescope (APT), a modified 0.5 m Baker-Nunn Schmidt telescope situated at Siding Spring Observatory, Coonabarabran, Australia, was opened in June 1989. It features the unique combination of an extremely fast (f/1) optical system with a CCD (Charge-Coupled Device) camera at the prime focus, capable of both fast (50 Hz TV-rate) imaging and slow-scan integrated readout via a low noise Correlated Double Sampling amplifier. This combination of optics and detector gives a wide field (0.9° × 1.4°) suited to observing extended objects including the LMC, SMC and galaxies in the Sculptor group. First images from the APT are presented along with the results of noise, linearity and dark current measurements made to date with a 12-bit analog-to-digital converter. Results were (ADU = Analog-Digital Unit):

In 1931 Karl Jansky established that radio noise was associated with our own galaxy–the Milky Way. For a decade and a half there was little follow-up; those of us who were associated with low frequency radar during the war regarded it as a nuisance which could limit the detection range of enemy aircraft. Grote Reber was the first to make a detailed but fairly low resolution map of the radiation from the galaxy showing, for the first time, some detailed structure. The event which we celebrate today occurred when Gordon Stanley, Bruce Slee and I showed that three of the discrete sources that we had discovered could be identified with visual objects. One was with the Crab Nebula, a supernova remnant within our own galaxy and the other two with galaxies, far beyond our own system, in the constellations of Virgo and Centaurus. Thus began extragalactic radio astronomy. In 1982 at the Noosa meeting of the ASA, I gave an account of those early years, later to be published in the ASA Proceedings. As I don’t wish to repeat myself, I propose to speak on my involvement in a later development which was to extend the observable scale of the universe to look-back times as great as the age of the oldest stars in our own system. The first important step was Graham Smith’s identification of Cygnus A with a galaxy that was much fainter than our two. The spectrum by Minkowski revealed an instrinsically highly-luminous galaxy with strong emission lines and opened up the possibility of discovering similar objects at significantly greater distance. This was achieved nine years later with the building of the Owens Valley Observatory and my title of ‘Radiophysics in Exile’ comes from the fact the observatory owed its existence and early successes very largely to past and future staff members of Radiophysics. They were, in order of appearance, J. G. Bolton, G. J. Stanley, K. C. Westfold, J. A. Roberts, V. Radhakrishnan, D. Morris and K. I. Kellermann. Some still bear . the scars–Westfold left the tip of one index finger in the Owens Valley!

The Logo of the Australia Telescope National Facility (ATNF) depicts a linear array of six antennas in the Southern Hemisphere. Precision measurement of this image implies that the Compact Array is located at latitude 37° south and azimuth 176°; this corresponds (surprisingly) to an approximately north-south array. Furthermore, the ATNF Logo was apparently prepared at LST 04h 00m.