Cosmic ray transient variations are signatures of the underlying solar processes which affect the heliomagnetic structure. They can be found in the data from surface systems, such as neutron monitors and muon telescopes, and from shallow underground muon telescopes. Although sometimes observable at all latitudes, the global distribution of the effects is important in determining the structures and causes. Three transient variation types are known, namely Forbush decreases, ground level enhancements, and quasi-periodic fluctuations. The latter category includes some variations which are, perhaps, too long-lived to be considered truly transient. In this review, the detection techniques and background of cosmic ray research are followed by a summary of some observations in each transient category. The heliomagnetic structures and dynamics inferred from such transients are discussed together with the possible impact such events can have on human activity.

An outline is given of the main research programs currently in progress at the Carter Observatory. These include: the establishment of a set of standard star magnitudes and colours in the Vilnius seven-colour photometric system; the study of galactic and extragalactic star clusters using Vilnius and broadband photometries; binary stars and the development of APTs; and the history of Australasian astronomy. The role of Carter Observatory Honorary Research Associates is described and mention is made of the joint New Zealand/Japan program to observe gravitational microlensing effects, discover variable stars and patrol selected clusters of galaxies for supernovae.

In this paper possible causes of line splitting in emission near the local plasma frequency are considered in connection with drift pair solar radio bursts. The basic model envisaged for the bursts involves a bunch of electrons streaming through the solar corona at several times the thermal velocity of electrons. The emission process assumed is the transformation of coherently generated electron plasma waves (I-waves) into electromagnetic waves (t-waves) with little change in frequency.

The radio source associated with Circinus X-1 has been observed several times at Molonglo since 1970 and some of these observations have already been reported (Whelan et al. 1977). In 1977 the source was again observed, this time for 17 consecutive days and during these observations the position and flux of the reference source 1505-56.9 were more precisely determined. A few sporadic observations have also been made in 1978. This note brings together the new observations and all the old measurements which have been corrected on the basis of the new data for 1505-56.9 Other observations have been made which were not calibrated against this source but these have not been included in this note since they are less well calibrated.

Described here is the new infrared camera/spectrograph, IRIS, that was brought into operation at the Anglo-Australian Telescope early in 1991. A number of scientific discoveries are used to demonstrate the capabilities of the instrument.

The study of radio galaxies situated within clusters of galaxies has become a broad field, with hundreds of papers published in the last few years. This review will therefore be restricted mainly to consideration of the interactions between the extended components of radio sources in clusters and the diffuse gas (intracluster medium, ICM) which occurs in clusters. In particular, attention will be focused on what we can learn about the ICM from this interaction, in conjunction with other data such as X-ray observations. In the case of quasars in clusters of galaxies the emphasis is rather different, so discussion of this topic is deferred to section 6.

We demonstrate the presence of a cluster of hot, population I stars at the very centre of the Galaxy, using the depth of the first overtone band of CO and the presence of emission in He I 2 ·058 μm and [Fell] 1·644μm to identify stars. The cluster is very compact and comprises at least several hundred stars. They lie close to the nonthermal radio source Sgr A* and dominate the luminosity and mass loss of the Galactic core. Their presence suggests that a starburst occurred at the Galactic centre.

A great deal has been learnt about supernovae over the last 500 days, or so. The major deficiencies in theory highlighted by the case of SN 1987A are briefly reviewed, as are the sucesses.

We present observations made at 80 MHz with the Culgoora radioheliograph of the compact central components of the radio source Centaurus A, which is associated with the peculiar galaxy NGC 5128.

The ratio of the mass density in visible galaxies to the upper limit for the HI mass density determined from the lack of continuous Ly-α absorption in QSO spectra is 3 × 104. Thus, if galaxies form by condensation from an intergalactic medium, the process must be extremely efficient. Although no absorption due to a continuous distribution of intergalactic HI has been detected, many QSOs have been discovered that have absorption lines in their spectra, which have redshifts very different from the emission lines, and may be produced in clouds of integalactic HI. As would be expected if this were the case, the proportion of QSOs with absorption lines in their spectra is greatest for those which have large emission line redshifts. Another possibility, especially for those absorption lines in redshift systems with Z abs nearly equal to Z em , is that the absorption lines are produced in clouds surrounding the QSO.

In 1983 ultra high energy γ-rays were detected from Cygnus X-3. This was of particular interest since it is the first identifiable source of cosmic rays. Since then, there has been an explosion of interest in the field with more than twenty air shower arrays planned or being used to search for γ-rays at energies above 1014 eV. Observational techniques for both very high energy and ultra high energy γ-ray astronomy are described and existing and proposed experiments reviewed with particular reference to their geographical locations. The results obtained so far are summarised together with some of the models proposed to explain them.

In a technical sense radio astronomers do not use the radio spectrum; they are listeners only, and when the science began they had to listen in the quiet spaces between transmitting services. Radio astronomy was first recognized as a service by the International Telecommunications Union (ITU) in 1959, and the first frequency allocations were then made for it as a ‘passive’ service. In 1963 and 1971 further allocations and frequency protection were obtained at specialized World Administrative Radio Conferences (WARC). The allocations were required for two purposes: (i) to protect the frequencies of the most important spectral lines of atoms and molecules, and (ii) to provide a series of bands for continuum observations. The general protection so far provided has been vital to the growth of the science, and its continuation is of the highest priority to the future life and development of radio astronomy.

It has recently been reported (Cini-Castagnoli et al. 1973; Jacklyn and Cini-Castagnoli, 1974) that Jupiter may be responsible for a modulation component in the counting rate of underground cosmic ray detectors on the earth. The evidence suggests that a screening mechanism is operating, in as much as the observed counting rates are diminished when Jupiter is within the field of view of these detectors. The magnitude of the effect is larger than can be accounted for by simple line-of-sight obscuration by the planet itself, and it has been suggested that the intense and extensive Jovian magnetic field is producing the effect.

Observations of the solar surface indicate a cellular structure, photospheric granulation, which, as suggested by Wilson and others, could arise from a shallow convection layer. The basic observed granulation pattern has been likened to a hexagonal cell type structure.

We present the results of spectral observations on Nova Vulpeculae (1) 1984 (RA = 19h24m, Dec = 27° 15′), taken on 1984 August 21 (JD 2445934.4) and 1984 August 31 (JD 2445944.4). The data obtained gives additional information on the nova’s spectral evolution presented by Andrillat and Houziaux (1985), filling the gap in their observations.

Cen X-3 and Her X-1 are the only two X-ray binaries which are known to pulsate periodically (at 4.8s and 1.2s respectively) in the X-ray region. The latter was identified with a fourteenth magnitude light and spectrum variable HZ Her, which was subsequently found to exhibit 1.24 second optical pulsations during certain phases. The possibility that Cen X-3 may prove to be as interesting an object optically has resulted in a wide spread search for its optical counterpart.