The Magellanic Clouds are the nearest major extragalactic objects to the Milky Way. The study of young giants or supergiants in the Clouds enables us to obtain information regarding the birth rates and evolution of young massive stars in those systems, free from biases inherent in similar studies in the Galaxy. Although the Magellanic Clouds have been studied by an extremely large number of research workers at optical wavelengths, it is only recently that significant infrared observations have also been undertaken (e.g., Glass 1979, McGregor and Hyland 1981, Cohen et al. 1982). Cool supergiants in the SMC have been studied optically by Humphreys (1979). She found that most are very metal deficient, and should be classified spectroscopically as M0.

We have carried out a survey of the 115 GHz CO emission (J = 1→0 transition) towards the Carina nebula (NGC 3372) using the Epping 4 m radio telescope of the CSIRO Division of Radiophysics. Of all the molecules detected in the interstellar medium CO is perhaps the best tracer of molecular clouds. It is an abundant molecule (second only to H2) and its line emission at microwave frequencies occurs at relatively low excitation.

There is a difference of opinion as to whether W33, an HII-region/molecular-cloud complex of size about 15′ arc centred near l = 12°.8, b = -0°.2 is a single object or a chance line-of-sight alignment of two complexes at completely different distances.

NGC 5128, identified with the radio source Centaurus A by Bolton et al. (1949), is a remarkable galaxy which appears to consist of an elliptical or SO galaxy crossed by a strong dust lane. The early idea that this represented a pair of colliding galaxies (Baade and Minkowski 1954) powering the extended double radio source fell out of favour but has recently been revived (Malin et al. 1983) in the light of extensive kinematic evidence. However, the interpretation of the data is not yet complete, and it has also been suggested recently that NGC 5128 is really a spiral galaxy with a spectacularly large bulge (Marcelin et al. 1982).

While Centaurus A (NGC 5128) is not a particularly powerful radio galaxy, its proximity (˜ 5 Mpc) permits us to obtain linear resolution an order of magnitude better than can be obtained for the more powerful, distant radio galaxies. Thus one can hope to make meaningful comparisons between the morphologies seen over the electromagnetic spectrum from γ-rays to metre waves. This should lead to a more complete understanding of the energy production mechanisms and evolutionary histories of these objects.

The Molonglo Observatory synthesis telescope (MOST) of the University of Sydney (Mills 1981) produces maps of the 843 MHz continuum emission from fields of width 23′, 46′ or 70′ arc. The telescope comprises two co-linear east-west cylindrical paraboloids each 2186λ in length and separated by a gap of 43λ. For each paraboloid a phasing network (Durdin et al. 1984) generates a comb of 64 contiguous fan beams. Mapping is accomplished in real time during a 12-h observation by overlaying, in the map plane, the instantaneous cross-correlations of corresponding beams. The synthesized point-source response (beam) produced by this method has a width of 43″ (E-W) by 43″ cosec δ (N-S).

PKS 1318-43 was first identified with the elliptical galaxy NGC 5090 by Ekers (1969) in the Parkes catalogue. Schilizzi and McAdam (1975) mapped the source with 2.9 arcmin resolution at 408 MHz using the Mills Cross, resolving the source into an extended double structure approximately 15 arcmin in extent at p.a. 36°. Schilizzi (1975) also noted a possible optical link with an edge-on spiral (NGC 5091) ~75 arcsec to the south-east. Figure 1 shows a print of the two galaxies taken from the UK Schmidt J survey film. During 1980, in collaboration with K. J. Wellington, RMS mapped the source at 1415 MHz with the Fleurs Synthesis Telescope (FST, Christiansen 1973).

A sensitive search has been made for OH maser emission from a sample of 16 symbiotic stars. This sample has been selected on the basis of infrared optical depth and variability, so that the stars within it have circumstellar shells similar to those seen in the well-known OH/IR and OH/Mira stars. There were no significant detections, except for one unassociated background source, and we conclude that the presence of a hot binary companion inhibits any possible OH maser action.

There are many thousands of photographic star plates in observatories throughout the world, and the number is being added to continually. A major difficulty in making use of the information contained in them lies in the measurement of position, and other data, of star images on the plates, and in bringing the data to a form suitable for computer processing. Manual methods are impossibly slow and laborious for an extended program of measurements, and automatic machines on the market are prohibitively expensive for small observatories with limited resources.

In its normal synthesis mode of operation, the Molonglo Observatory Synthesis Telescope (MOST) tracks a region of sky for a period of 12 hours with 64 real-time fan beams having high sensitivity at 843 MHz (Mills 1981). It thus provides an excellent opportunity to monitor the sky at the same time for transient radio events. During a 12 hour synthesis observation the fan beams rotate 180° on the field. Thus any sources producing occasional radio transients can be located by analysing the positions of the beams on which the events are recorded. Futhermore, by rejecting events which occur simultaneously on non-adjacent beams, local terrestrial sources of impulsive interference may be eliminated. This technique for recognizing extra-terrestrial sources was of considerable value in the first Molonglo pulsar search when only two beams were used.

The polarization characteristics of celestial radio signals are a major part of the observable nature of the radiation. Stokes polarimeters, instruments for measuring the complete polarization properties of radiation, are usually narrowband devices in order to minimise depolarization effects originating in the source or in the medium through which the radiation propagates. To measure the broadband polarization behaviour of a source, a Stokes polarimeter-spectrometer is required. Such an instrument allows the frequency dependence of each Stokes parameter to be deduced, making it possible to apply corrections to each parameter to account for known forms of polarization distortion (e.g. Faraday rotation). It is also possible to remove delay distortion from impulsive sources such as pulsars by processing the spectrometer data according to the usual de-dispersion algorithms. In some studies observation of distortion phenomena may be the major aim and a polarimeter spectrometer greatly facilitates measurements of these effects.

For many years now, large plastic scintillator and geiger counter muon telescope systems have been used underground for studies of the small variations of the cosmic ray particle intensity that occur at primary energies around 1011 – 1012 eV. Although long-term deterioration in telescope counting efficiency is liable to take place it has been possible to take care of it sufficiently well to allow accurate observations to be made of the important daily variation and of transient events such as the Forbush Decrease and the solar flare increase.

The baseline of East-West array of the Fleurs Synthesis Telescope (FST) has been extended from 786 metres to 1585 metres by the addition of two 13.7 metre dishes. A digital receiver has been built to accommodate the extra delay and correlation requirements, low noise FET preamplifiers have been installed on the large antennas, and a software package has been developed for processing observation data on a VAX 11/780. The FST is now capable of producing accurate wide field maps at 1415 MHz with a resolution of 20 arc seconds and a sensitivity of several milliJansky.

The four-fold advantage over a conventional 4 m reflector which naive information theory confers on the 1.2 m UK Schmidt telescope (Dawe and Watson 1982, Watson 1983) is only approachable in practice under certain rather specific conditions. These relate principally to the surface distribution on the sky of the object classes of interest, and the type of detection employed. Clearly, for general survey work with sky-limited photographic detection, the information advantage is high, but it can be demonstrated (Dawe and Watson 1983) that the relatively new technique of multi-object fibre-optics spectroscopy (eg Hill et al. 1980, 1982, Gray 1983, Lund and Enard 1983) with linear detectors offers very high potential in certain regimes of operation. In particular, the UK Schmidt telescope (UKST) equipped with 400 fibre channels has four times the effective light grasp (= number of fibres utilized × aperture) of a 4 m reflector (with a 1 deg field and equipped with any number of fibres) for target objects with surface densities between approximately 1 and 10 per square degree (Dawe and Watson 1983). Objects ranging from galactic variable stars to quasars lie within these limits, but of especial interest are galaxies, whose apparent luminosity function in this range of surface densities runs from magnitudes 15 to 17 (MacGillivray, private communication). Large-scale, medium accuracy (60 km s−1) redshift surveys of galaxies within this magnitude range promise to be extremely fruitful (Davis 1982) and are easily within the reach of the UKST fibre-coupled to a CCD spectrograph (Watson and Dawe 1984).

It is easy to feel, on an intuitive basis, that primary cosmic rays of at least some energy range will be able to reach a satellite in earth-orbit from all directions above the local geometric horizon and from essentially no directions below the horizon. This argument suggests that directional cosmic ray detectors on board satellites may safely assume that the only particles received from earthward directions must be splash or albedo particles from the atmosphere, and that any equipment liable to possible radiation damage should be preferentially located on the earthward side of the satellite. In actual fact primary cosmic rays can have quite sharply curved trajectories in the magnetosphere, thereby enabling some particles to gain access to a satellite from a range of directions below the local geometric horizon. The present work presents recent quantitative results on this matter.

After 21 years the Parkes radio telescope has undergone a major refit. A new VAX-11/750 running VMS has replaced the aged Digital Equipment Corporation PDP-9 computer. Other new equipment includes two systems not previously available — the Mk II RING communication system (Willing and Abies 1983) and the ‘observer workstations’.

Waves of variation in the daily average cosmic ray intensity at the Earth’s surface were first detected in the neutron monitor record. Following the abnormal cosmic ray storm of September 1978, a sinusoidal 13.5 day periodicity was observed in the average intensity (Pomerantz and Duggal 1979), persisting for at least two solar rotations. Further observations, including underground data from the southern hemisphere, confirmed that not only were the waves isotropic but exhibited approximately a p−1 variational dependence on primary rigidity p (Duggal et al. 1981). No further evidence for this kind of wave has yet come to light. However, in the latter half of 1982 a series of 27-day waves that were apparently of a different character were detected. The evidence for their presence resulted from an analysis of the disturbed period that followed the occurrence of the large Forbush Decrease commencing 13 July 1982. It seemed at first that they could be described as anisotropic waves of the well-known interplanetary North-South asymmetry (Jacklyn and Pomerantz 1983).

Recently, a new branch of astronomy has emerged following the detection of ultra-high energy (UHE) γ-ray emission from Cygnus X-3 by Samorski and Stamm (1983). This discovery was made using the extensive air shower (EAS) array of the University of Kiel, Germany. Such arrays are designed to detect EAS, the cascades of secondary particles (mainly electrons and protons), which are generated in the atmosphere by the interaction of cosmic ray nuclei of energy greater than ˜ 1015 eV. These arrays are also sensitive to EAS initiated by primary γ-rays and, depending on their design, have angular resolutions as good as the SAS-II and COS-B γ-ray telescopes which operated at ˜ 100 MeV energies. At present, there is no effective way to veto proton or nucleus-initiated EAS and so one must look for a significant excess of EAS from within a cone of resolution centred on a suspected source direction.

The ‘holographic’ technique for accurately measuring the surface figure of large reflector antennas, described by Bennet et al, (1976) and Scott and Ryle (1977), has many advantages over older conventional survey methods. These include high speed, low cost, and the absence of any need for additional complex mechanical or optical survey devices. In essence, the technique consists of measuring the complex far-field response of the antenna at a single frequency using a terrestrial, satellite-borne or celestial radiation source of small angular diameter. This two-dimensional pattern is then Fourier-transformed to yield the complex illumination function across the antenna aperture. Antenna surface deviations are manifested as phase fluctuations in this function. In practice, a second antenna is needed to provide a phase reference.