The most favourable methods of observing the phenomenon of gravitational lensing are through high-amplification events and the time delay between the images. These effects provide us with the information to determine the Hubble parameter and the matter distribution in the universe. The image properties due to micro-lensing can be used to find the size and structure of the source.

Observations of the red giants in NGC 1866 in the Large Magellanic Cloud, made by Arp and Thackeray provide a strict test for core helium burning models of about 5M⊙. The main observational features to be reproduced theoretically are the luminosity of the red giants, the range in effective temperature that they occupy and the ratio of the number of giants near the blue end of this range to the number at the bottom of the red giant branch. Meyer-Hofmeister attempted a theoretical fit to these observations using the initial (X, Y, Z) composition (0.602, 0.354, 0.044) and assuming the stars to have formed uniformly over a period of 1.5 × 107 years about a mean age of 5.75 × 107 years. Although she was able to fit the luminosity and effective temperature spread of the red giants, her theory predicted far too many stars at the bottom of the red giant branch relative to the number of bluer giants.

It is a well established observational result that young stars exhibit differences in chemical composition. The differences are comparatively large. For example, some stars have metal abundances as high as 3/2 solar-value while others have abundances as low as 1/2 solar-value. The result was obtained through spectroscopic and photoelectric studies of stars with ages of a few times 108 yr and indicates that the interstellar medium is chemically heterogeneous at the present epoch.

The over-estimation of the flux density of radio sources near the lower limit of a survey has often been considered in the past. The use of digital recording and analysis techniques now enables a quantitative approach to the problem. Monte Carlo techniques may be used to determine the error distribution, including any systematic bias.

The 4-m radio telescope of the CSIRO Division of Radiophysics at Epping is being used to survey the line emission associated with the 1→0 transition of CO (rest frequency 115.271 GHz) in the southern Milky Way. The programme includes mapping the CO distribution across giant molecular-cloud/HII-region complexes. As a first stage the emission has been observed towards bright southern HII regions. These results will not only serve as a basis for future extensive mapping but will also provide data which is directly comparable with observations of other molecular lines that have been made towards the HII regions.

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):

The magnetic structure in the source region of a type II burst and along the path of the type II disturbance has remained an enigma despite over 20 years of radio observations of the Sun (see e.g. reviews by Wild and Smerd (1972) and McLean (1974)). This paper describes the first radioheliograph observations of a type II burst near coronal magnetic structures depicted by soft X-ray pictures. It will be shown that three separate lanes in a type II burst are associated with three separate source regions each located almost radially above a soft X-ray loop. To explain these observations a model is derived in which a wide-fronted m.h.d. disturbance travels from the flare explosion along magnetic field lines and then intersects successively with three coronal streamer structures each located above a soft X-ray loop. An estimate of the magnetic flux density along the soft X-ray loops is obtained from the velocity of the m.h.d. disturbance.

Abstract: The Australia Telescope is an advanced radio astronomy facility planned to satisfy the major research requirements of Australian scientists. The construction project, begun in 1983, is now well along the way to completion as an Australian Bicentennial activity. The civil works at the main Culgoora site are complete. The construction of the seven 22-m antennas has begun: the first will be handed over in November 1986, the last a year later. Most other areas of the project – feed construction, receiver construction, computer development etc. are on schedule.

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).

The Molonglo Observatory Synthesis Telescope (MOST) has been used to observe the Sun with total-power fan-beams having a one-dimensional resolution of 41 arcsec at 843 MHz. The scans reveal clearly the rotation and evolution of the slowly-varying component as well as some burst activity. Low radio brightness features have also been identified, but the exact relationship between these features and coronal holes is, as yet, unclear. Several partial synthesis observations have been used to generate two-dimensional radioheliograms.

During recent years it has become rather clear that the β-Cephei variables are in a hydrogen-buring stage of their evolution. The 8 (β-Cephei variables which have been found in the Scorpio-Centaurus association highlights this. The 6 of these variables for which Glaspey (1971) provides (β, (u – b)0) photometry all fall at the tip of the sequence in the Hertzsprung-Russell diagram. This indicates that (β-Cephei stars are in the final stages of core hydrogen burning. This is in good agreement with the position of the β-Cephei strip of Watson (1972) in the H-R diagram.

The β Cephei variables are a group of short period pulsating variables of early spectral type for which no satisfactory physical driving mechanism has yet been discovered. Further it is not clear what form of pulsation these stars are undergoing. The existence of a beat phenomenon and a phase of spectral line broadening is well established in some of these stars. This extends to observed spectral line doubling in three stars, BW Vul, σ Sco and 12 Lac. Because of the difficulty in explaining these phenomena with purely radial oscillations, Ledoux (1951) first suggested the possibility of non-radial oscillations. Other stars in the group, γ Peg, δ Cet, #x03BE;’ CMa and β Cep have approximately sinusoidal velocity and light curves with little indication of spectral line broadening. For these there is probably no a priori observational need to look beyond purely radial oscillations. It is of course conceivable that different modes of oscillation are present in different members of the β Cephei group. However, if line profiles are calculated for various proposed oscillation modes and compared with the observations, it may be possible to eliminate some suggestions and hence limit the search for an instability mechanism.

The outburst and storm of more than four hours’ duration that accompanied the importance 2 flare beginning at 0h25m U.T. on 9 June 1968 were observed at 80 MHz with the Culgoora radioheliograph. More than 104 heliograms in both senses of circular polarization were recorded at one-second intervals both as cathode-ray-tube photographs and as digital characters on magnetic tape. It is the purpose of this preliminary account to summarize these observations and bring attention to a new phenomenon observed before the start of the flare.

A catalogue of 38 supernova remnants (SNRs) identified in the Large and Small Magellanic Clouds from X-ray, optical and radio observations has recently been presented by Mills et al. (1984). One important consideration is the completeness of this catalogue and of the Galactic catalogues with which it is compared. These are currently being investigated.

A proposal for a medium rigidity muon telescope system to be installed at the U.S. South Pole Station for observations of time variations of cosmic ray intensity is at present being prepared by Professor Pomerantz, Director of the Bartol Research Foundation, University of Delaware and Drs Jacklyn and Duldig of the Cosmic Ray Section, Antarctic Division, Department of Science. A novel approach to medium energy cosmic ray observations viewing in equatorial to mid-latitude directions is described. The absorber depth required for the proposed 50-1000 GV rigidity range would be achieved by locating the telescope system at a depth of approximately 7 metres water equivalent (MWE) in the ice and viewing at high zenith angles. Optimization techniques used in the telescope design are presented together with the unique advantages of the location. Justification for the experiment and comparison with important observatories in this rigidity range are also discussed.

Results from optical and infrared observations of SN 1987A obtained at Cerro Tololo Inter-American Observatory since maximum light (100-400 days after core collapse) are reviewed.

Results of recent surveys of high velocity HI clouds with the 80-ft reflector at Dwingeloo and with the 260-ft x 80-ft standing paraboloid of the Ohio State University are combined. They show that clouds with high negative radial velocities occur mainly in the longitude range 50° to 220° from N. to S. galactic poles. However, nearly three times as many clouds are found north than south of the galactic plane. Clouds with high positive radial velocities are much less numerous than the negative velocity clouds. They have been found between longitudes 260° to 350° and scattered around lII = 75°, bII = +45°.