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.

The radio source PKS 0511-48 is among the hundred strongest southern sources at low frequencies. It was catalogued in the Parkes survey (Ekers 1969) and mapped with the Molonglo Cross at 408 MHz by Schilizzi and McAdam (1975) with a resolution of 2′ .6 arc. It appeared in that work as a complex source, with an integrated flux density of 8.8 Jy. A search for optical identifications was made by Tritton and Schilizzi (1973), but none were found to a level of B ~ 19. We have inspected the field on the ESO B survey film, and find a group of ~ 20 faint galaxies (approximately 19-20 mag).

There is growing evidence for the notion that large grains are an important constituent of the interstellar medium. It has been found to be necessary to invoke the presence of large grains (of radius a > 1.0 μm) in a number of circumstellar shells, including those around Eta Carinae, and some late type giants and supergiants. Most recently, as a result of IRAS observations, the same idea has been used in the interpretation of the extensive optically thin disks found around some young early type stars. It is important to establish size constraints on these grains, so as to determine better the probable mix of interstellar grains. Previous work on AG Carinae suggested merely that the grains in the circumstellar shell need to be larger than 1 μm, but gave no information regarding the maximum size which would be acceptable. In this paper, we explore the question of the characteristic size of the dust grains in the AG Carinae shell, by fitting the spatially integrated model energy distribution to observations over the wavelength range 360 nm–100 μm, and conclude that silicate grains of radius ~ 1.0 μm give a satisfactory fit to the spectrum and angular distribution, but that grains appreciably larger or smaller than this radius are unsatisfactory.

Since its commissioning in 1981 the Molonglo Observatory Synthesis Telescope has been used by the Astrophysics Department in the University of Sydney for many astronomical programs. These include completed surveys of both Magellanic Clouds made to study their SNR and HII content. The SNR work is essentially complete with 55 remnants identified and firm indications that the previously assumed evolution of a typical SNR (if such exists!) is incompatible with observation. The cataloguing and analysis of the HII regions and planetary nebulae data is complete in the SMC but barely started in the LMC. Other observing programs include the mapping of southern radio and ‘normal’, galaxies, the study of variable sources, ‘deep mapping’ of a selection of far southern fields for cosmological studies, studies of mass loss stars, the Galactic centre and a general survey of a strip along the Galactic plane as a long term program. In addition, advantage has been taken of the ‘real-time’ beams for pulsar studies and for the development of a ‘transient event recorder’ to permit a search for pulsed or other rapidly varying phenomena during normal map synthesis. Some of these programs have been completed but the majority are still in progress.

In March 1963 a paper by Hazard, Mackey and Shimmins in Nature, announced an accurate position for the radio source 3C 273. This was subsequently identified as the first known quasar. Through an innocent editorial mistake, the affiliation of the first author was wrongly attributed. This caused long-term animosity between the Physics Department of the University of Sydney and the CSIRO Division of Radiophysics.

In this paper we give an account of the corrections that must be made to the formula for the emissivity ηf due to a power-law energy distribution of ultrarelativistic charged particles in a uniform magnetic field B0 in directions well away from the field lines when the effects of upper and lower cut-off values E2 and E1 in the energy distribution are not negligible.

Phase coherent interferometers with intercontinental baselines became possible because of the development of stable frequency standards. With sufficiently stable frequency standards, no connection is necessary between the two ends of an interferometer. The first VLBI experiments were conducted by a group at the University of Florida who used an intensity interferometer with independent tape recorders for observations of Jupiter. Later, they changed to a coherent system using crystal-controlled oscillators. Since then, several interferometer systems have been developed. A Canadian group developed a system using video tape recorders at each end of the interferometer. They recorded the data in analogue form and managed to bring the two tapes together and to synchronize them to an accuracy of better than a microsecond. After synchronization, the outputs were combined and fringes extracted. Their system has a bandwidth of about 4 MHz. No-one else has attempted a wide-band analogue system.