The technique of aperture synthesis is well developed in radio astronomy. When applied to the optical regime, aperture synthesis allows one to partially overcome the blurring effects of the atmosphere and increase the angular resolution of large telescopes to the diffraction limit.

MAPPIT (Masked APerture-Plane Interference Telescope) is a multi-element interferometer which operates at the coude focus of the 3.9 m Anglo-Australian Telescope. This instrument has recently been reconfigured to operate in a dispersed mode so that simultaneous observations in a band of wavelengths are possible. We will discuss this instrument’s new mode and present observations of the double star δ Sco and an angular diameter of the previously unresolved red giant β Gru.

While monitoring Barnard’s star in Ophiuchus for flare activity in August 1969, we accidentally recorded two bright flares on an early type star, 66 Oph. Apart from Andrews’ unconfirmed observation of a flare on a B8 star and Eggen’s report of a flare on the β Cephei Variable, (BO) HD 199 140, no other record of an early type flare star is known to the authors.

In this paper we present maps showing the distribution of HCO+ (J= 1→0 transition at 89.18855 GHz) in the direction of NGC 6334 as a function of radial velocity, lhe observations were carried out in May-June 1979 as part of a larger program of HCO+ observations (Batchelor et al. 1980, 1981) using the Epping 4-m millimetre-wave radio telescope.

Studies stimulated by the interpretation of the Elatina formation in South Australia as a fossil record of solar activity have led to discoveries of previously unnoticed features of the sunspot cycle record and to a theory of origin of the sunspot cycle that postulates a solar core in torsional motion and a magnetomechanical wave that couples to the photosphere. The considerations supporting the solar interpretation of the Elatina formation are gathered together.

The interaction of the solar wind and the Earth’s magnetic field causes the field to be confined within a region shaped like a liquid drop. The solar wind flows past this region, the magnetosphere, without penetrating it. The precise shape of the magnetospheric boundary is of interest for hydromagnetic studies, but these usually begin from assumptions about the nature of the magnetic field. Any specification of the boundary which makes no reference to the field must therefore allow more flexibility in such studies.

The Physics Department at the University of Otago, Dunedin, New Zealand, has over the past three years commenced a research and teaching programme in astronomy and astrophysics. Observing facilities now include two metric wave meridian transit telescopes at a site 6 km from Dunedin and a 16-inch optical telescope, formerly at Mt John, which is now sited 4 km from Dunedin at the Signal Hill observatory built by the University’s Surveying Department for geodetic work.

During the interval May 1968 to March 1969 the 80 MHz radioheliograph at Culgoora has been used in a detailed study of the intensity variations in the pulsars CP 0834, 0950, 1133 and 1919. Some preliminary results for CP 1133 and 1919 have already been reported.

From early experiments in 1966 (Cole 1968) the acousto-optical radio spectrograph has been developed at CSIRO to a sensitive, multi-channel spectral-line back-end. The principles of the instrument are described in detail elsewhere (Lambert 1962; Hecht 1977; Milne and Cole 1977). By means of a Bragg interaction between a laser beam and an ultrasonic beam derived from the radio signal, light is diffracted into an order whose light intensity distribution is accurately related to the power spectrum of the radio signal. In the earlier spectrographs the spectrum was recorded photographically (Cole 1973a, b; Hecht 1973) but this was limited to strong spectral features. To study weak spectral features a stable, linear system was needed with large dynamic range. The combination of an array of photodiodes and computer would be capable of observing these weak spectral features (Cole and Abies 1974). Development since 1974 has been a progressive identification of sources of thermal and mechanical instability and of excess noise in the spectrograph system.

In 1966 McGee, Gardner and Robinson carried out an exploratory search at 1665 MHz for OH in 26 thermal sources in the southern Milky Way and reported emission in 12 sources. Subsequent measurements by Robinson, Goss and Manchester confirmed emission from six of these and detected four additional OH emitters.

Rich clusters of galaxies are a common feature of the large-scale structure of the Universe. Those studied so far, show striking regularities with

1. (a) a smooth radial gradient of number density.

2. (b) ’isothermal’ distributions, which according to Bahcall (1975) have a scatter of only ±15% in the size of their characteristic core radii.

3. (c) their limiting structural diameters are ~50 Mpc (cf. Abell, 1975), if they are identified with superclusters.

4. (d) the magnitude of the velocity dispersion about their centres is generally 600-1000 km s-1, and the velocities are cpnsistent with a gaussian distribution (Yahil and Vidal, 1976; also Faber and Dressier, 1976).

5. (e) The extreme velocities are generally within ±3000 km s-1, and for Coma are ∼2400 km s-1 (Tifft and Gregory, 1976).

6. (f) elliptical galaxies tend to predominate near the centre, spirals in the surrounding loose groups.

Clusters of galaxies appear to contain much more mass than just that of the galaxies which provide most of their optical luminosity. There are two important ways to investigate the structure of their gravitational potential wells, firstly by an analysis of the radial velocities of the cluster galaxies, and secondly by a study of the X-ray emission from the hot gas which forms part of the intra cluster medium. We present new samples of radial velocity data for three clusters, and discuss some simple types of models of the X-ray sources.

The Antarctic Submillimeter Telescope and Remote Observatory (AST/RO) is a highly automated 1·7 m diameter telescope aimed at exploiting the superb submillimetre skies of the Antarctic Plateau for astronomy and aeronomy studies. It was recently installed at the Amundsen-Scott South Pole Station during the 1994/95 Austral season and is currently undergoing its first winter-over of operation. In this paper we briefly outline the capabilities of the instrument and describe some recent achievements culminating in the telescope’s first observations of the South Polar submillimetre sky.

Lynds 1642 is a small, somewhat insignificant dark cloud centred at 04h 33, — 14°20 (1950). On a IIIaJ UKSTU Schmidt plate it may be seen to lie within an approximately circular patch of nebulosity which we believe to be visible by reflection. Its galactic location (l = 210°.9 b = -36°.5) places it beneath the local arm in the direction of Orion and it is likely that it is seen by reflection of the integrated light of the stars in that region of the galaxy.

One of the most difficult tasks facing theoretical astrophysics today is to find a satisfactory model for the convective transport of energy in regions where the temperature gradient is superadiabatic. A number of such models have been proposed, such as the mixing-length theory and its extensions (Vitense 1953, Böhm-Vitense 1958, Spiegel 1963, Travis and Matsushima 1973 a, b, Parson 1969), to take into account the combined effects of convection and turbulence but it is generally agreed that, to-date, no satisfactory theory has been put forward.

The time dependent multimode equations for magnetoconvection have been solved numerically for a range of parameter values and cell sizes. The solutions demonstrate the nonlinear interactions between the different scales of motion and how the induced magnetic field is concentrated into the smaller length scale. The generation of mean kinetic and magnetic helicity occurs at low Prandtl number which has significant physical interpretations in the solar situation.

Recently E. M. Burbidge and P. A. Strittmatter1 have found that the DB-like star G61-29 has broad He emission lines suggesting a rapid rotation. The purpose of this paper is to suggest a further white dwarf candidate for rapid rotation.