We have undertaken a study of the 3-D spatial distribution of the older (τ ≥ 1–2 Gyr) stellar population lying beyond ~ 2 kpc in projected radial distance from the centre of the SMC. The study will eventually cover 120 square degrees including six overlapping Schmidt fields. Here we present the results from an area of 80 square degrees including the western, northern and north-eastern outer parts of the SMC.

It is well known that a molecular cloud complex with a radial velocity of 40 km s–1 is located in front of and near Sgr A, the non-thermal source at the centre of our galaxy. The motion of this cloud is generally interpreted as a contraction towards the centre. In terms of the general kinematics of our galaxy the existence of contraction is not firmly established – the main spiral features are either stationary with respect to the local standard of rest or expanding outwards from the centre (e.g., the 4 kpc expanding arm). However, as a result of a high-resolution study of the H2CO absorption arising in the molecular cloud, an alternative interpretation not involving contraction is suggested.

The plans of JACARA, the Joint Australian Centre for Astrophysical Research in Antarctica, for Australian involvement in future astronomical activities on the antarctic plateau, are outlined.

We describe the use of a multi-aperture Hartmann mask coupled to a slightly out-of-focus focal plane array imager to monitor atmospheric turbulence (‘seeing’) produced by refractive index fluctuations. The imager (a CCD) is located inside or outside the focal surface of the imaging system so that each sub-aperture of the Hartmann mask produces an image well separated from all of the other images produced by the mask. Since the depth of focus of the sub-apertures is an order of magnitude larger than that of the parent optical system, the individual images are still diffraction-limited. We obtain short (10 to 100 msec) exposures and monitor the position fluctuations of the images. Analysis of the position and intensity fluctuations of the images can be used to determine the atmospheric parameter r 0, the wind direction and velocity, and, under some circumstances, the distance of the turbulent layer from the observing site.

The thermal radio-frequency emission, Ev , per unit volume per unit frequency interval may be computed (e.g. from equations given by Oster) and compared with the volume emissivity E(Hβ) in the optical Hβ transition.

Radio pictures of the Sun from the Culgoora radioheliograph have already shown instances in which flares have initiated radio bursts in parts of the Sun remote from the flare position. In this paper we discuss two such events on 1968 May 4 and May 6, in each of which it appears that shock-waves arising from a flare produced distant prominence activity which led to the generation of metre-wave continuum radiation.

The bright radio emission from flare stars has three characteristic properties: high brightness temperature, high degree of circular polarisation and rapid temporal variations. Two proposed emission mechanisms, electron cyclotron maser emission (ECME) and plasma emission, are compared and contrasted. It is argued that although the important features of the emission can be explained in terms of either ECME or plasma emission, all three favor ECME. However, the escapes of the radiation through the second harmonic absorption layer remains inadequately understood, and as a consequence doubts about the ECME interpretation remain.

A new feature in the form of a jet formed by close juxtaposition of a number of highly polarized, separately resolved 80 MHz sources was observed as the late phase of a very complex outburst on 1971 January 25. We present here a source model which, we think, can explain the observed source properties. The early phase, also complex and involving numerous moving sources, will be described first.

Our knowledge of the universe comes from recording the photon and particle fluxes incident on the Earth from space. We thus require sensitive measurement across the entire energy spectrum, using large telescopes with efficient instrumentation located on superb sites. Technological advances and engineering constraints are nearing the point where we are recording as many photons arriving at a site as is possible. Major advances in the future will come from improving the quality of the site. The ultimate site is, of course, beyond the Earth’s atmosphere, such as on the Moon, but economic limitations prevent our exploiting this avenue to the degree that the scientific community desires. Here we describe an alternative, which offers many of the advantages of space for a fraction of the cost: the Antarctic Plateau.

The time and spatial distributions of the ‘energy flare indices’ which have been observed since Cycle 21 are analysed and 13 hot spots of energy flares during this period are given in this article. These active regions of the ‘hot spots’ appear repeatedly where there erupted the energy flares accounting for 63.2 per cent of the total indices. The characteristics of the hot spots of the energy flares and the relationship between the hot spots and the evolution of the large-scale magnetic fields are also further discussed in this paper.

Many of the X-ray pulsars for which X-ray lightcurves have been presented in the literature exhibit asymmetric emission beams. We postulate the existence of an off-centre magnetic dipole field embedded in the rotating neutron star and show that such a field leads to varying rates of matter transfer between an accretion dise and the neutron star surface, over a rotation period. Assuming that the accretion rate onto the surface is simply related to the luminosity, we show that most of the observed asymmetries can be accounted for by this mechanism.

Observational and theoretical constraints which apply to models of the precursor star before and at the time of explosion are presented. Stellar evolution sequences for the precursor star produced by various authors are described, and an attempt is made to define what these sequences tell us about the evolution of star of mass ∼ 20 M⊙.

Interesting observations have been made possible by the success of the acousto-optical radio spectrograph, a unique form of multi-channel filter type of spectral receiver whose channel outputs ian be sampled at high rates by a computer. Three spectrographs are available at the Division of Radiophysics. Two divide a 100 MHz spectral range into 512 channels and are normally dedicated to spectral-line work (Cole and Milne 1977) and solar work (Cole et al. 1978). The Parkes observations reported here use a more compact spectrograph, which gives increased performance — up to 270 MHz can be studied, divided into 256 frequency channels. The light deflector of this spectrograph was kindly supplied by Itek Corporation.

The changing total luminosity of SN 1987A between 2 and 1200 days after core collapse is illustrated and discussed. From about four weeks after outburst the supernova light curve was dominated by the release of radioactive decay energy; the major contributor being 0.078M ⊙ of 56Co. Recently an additional contribution probably from the decay of 57Co and 44Ti appears to be manifesting itself in the light curve. A gradually increasing fraction of the radioactive decay energy has probably been emitted at X- and γ-ray wavelengths; the fluxes are low and no recent measurements have been published. Most of the remaining radioactive decay energy appears to be emitted in the IR and is very difficult to measure. Other factors influencing the interpretation of the recent light curve are the uncertain contribution from long-lived radioactive isotopes and light-echoes. It is therefore premature to make any definitive statements on the contribution from the neutron star, although it is probably less than a few times 1037 erg s−1.

High-resolution observations indicate that very strong, small scale magnetic fields in the solar photosphere are concentrated into ropes which emerge through it. The scale of these ropes is only a few hundred kilometres across (Stenflo 1976) and their strength is estimated to vary between 1,000 and 2,000 G (Harvey 1977). These features are closely related to photospheric granular convection. The flux is observed as X-ray bright spots and sheet-like crinkles in the dark intergranular lanes, and is buffeted and shifted about by the granules (Dunn and Zirker 1973). Further, the crinkles can be resolved into separate features which outline small micropores as though a flux sheet at the end of a convection cell has separated into several isolated tubes (Galloway and Weiss 1981).

The 111–110 transition (frequency 4829.65 MHz) of formaldehyde (CH2O) has been recently observed in absorption against a number of continuum sources by Snyder et al. with the Green Bank 140-ft telescope.