Commissioning of the Anglo-Australian Telescope (AAT) is now well along and regular scheduled observing will begin at the end of June. This paper is an account of the main features of the telescope as they will appear to observers, and is intended in particular as a guide to people who are formulating programmes. First however some remarks on the telescope design.

The Circinus galaxy (CG) was discovered on a plate of an atlas of the nebulae of the southern Milky Way (Lyngå and and Hansson 1972). The detailed optical properties of this galaxy have been investigated by Freeman, Karlsson, Lyngå and Burrell and will be published in a paper by Freeman et al. (1976). The coordinates of the optical nucleus are (1950).

We present maps in the visible emission lines of [S II] and the infrared emission lines of H2, at 2.12μm, for several bipolar outflow complexes which exhibit jet structures. A comparison of the morphology of this infrared emission and that seen in visible emission lines shows both the visible and the H2 emission exhibit clumpy structure on similar scales. It appears that the brightest H2 emission occurs at the working surfaces of the jets. Virtually no H2 emission is associated with the jets themselves.

Velocity profiles are presented for several objects and possible emission mechanisms are discussed.

The 6 GHz transitions of the 2π3/2, J = 5/2 excited state of OH are present in emission in the direction of several OH-emission regions (Rickard et al. 1975; Knowles et al. 1976), and in absorption in compact thermal sources (Gardner and Whiteoak 1975). This has suggested that transitions in the next highest state near 13 GHz (J = 7/2) might also be widely observable. A single detection has already been reported in W3OH by Turner et al. (1970). In this paper we report the observation of narrow-band emission in several other sources.

We examine the period variations of ten eclipsing binary stars and from the combined result, attempt to construct a physical explanation for their behaviour.

T Centauri (HD119090) is a semi-regular variable with a period of 90d.61. The period is apparently stable but the photometry does not repeat very closely from cycle to cycle. The general Catalogue of Variable Stars gives a range of magnitudes from 5.5 to 9.0 and spectral types from KOe to M4IIe.

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.

Speckle interferometry (Labeyrie 1970, 1976) is one way of overcoming the blurring effect of the atmosphere in optical astronomy. When a short exposure is taken of an image, the seeing disc (typically several seconds of arc across) is seen to contain structure (speckles) down to the resolution limit of the telescope (0″.03 arc for the Anglo-Australian telescope). A second exposure 10 or so milliseconds later will show a different pattern of structure because the atmospheric irregularities will have changed. Multiple stars or source components within the same angular range of atmospheric irregularity (i.e. isoplanatic patch several seconds of arc across) will produce similar but displaced speckle patterns, and geometrical details of the components can be obtained from an autocorrelation analysis of the speckle pattern (Dainty 1975).

A photometric and spectroscopic survey of many of the cool H-deficient Carbon (HdC) stars, including the R Coronae Borealis (RCB) stars, has been undertaken. For the RCB stars we have data on both the low amplitude photometric variations at maximum light and the major declines, the latter being the most distinguishing feature between the RCB and HdC stars.

The photometric data at maximum light have been analysed using the Lomb-Scargle Fourier method, which has revealed many significant periodicities. From estimates of the temperature of these stars, an observational period-temperature diagram can be compared with theoretical models. These models have also enabled us to determine the evolutionary lifetime of these stars for comparison with observational parameters, e.g., period changes.

Over the last several years we have photoelectrically covered the declines (and the recovery from some of these declines) of a number of RCB stars, from which we have been able to characterise two extreme types of decline behaviour. In addition, we have for the very first time spectroscopically recorded the initial decline phase of one (the prototype, R CrB) of these stars.

Owing to the comparative lack of radio recombination line observations of southern HII regions, it has not been so far possible to make an overall interpretation of the data for these sources. However, observations of the H90α and H252α transitions by McGee et al. (1975) and Batty (1974) respectively have usefully extended the frequency range of observations to cover ∼ 0.4 to 8.9 GHz for a few southern HII regions.

A list of 901 radio sources with positional accuracies better than 0.5 arcseconds has been prepared from seventeen lists of radio source positions found in the literature. This compilation includes all such sources south of declination + 48° (the northern declination limit of the Compact Array of the Australia Telescope National Facility). Where available, optical identifications, optical magnitudes and redshifts are given as well as total-power flux densities.

The completion of the Uhuru (Forman et al. 1978) and Ariel V (Cooke et al. 1978) surveys of the sky for X-ray emission has resulted in many proposed identifications with individual galaxies and clusters of galaxies. The X-ray positions are not usually accurate enough to enable a positive identification to be made of the X-ray sources with optical or radio objects, and hence the identification is often based on statistical arguments — viz., the unexpected occurrence of unusual galaxies, radio sources or clusters of galaxies within or near the X-ray error boxes. There is usually no significant information available on the angular size of the X-ray emitter but in two or three cases (e.g. Perseus cluster, Coma cluster and Virgo cluster) the angular resolution is good enough to identify a broad component with dimensions approaching those of the whole cluster. This extended X-ray emission has been ascribed to either inverse Compton scattering of the 3° microwave background by relativistic electrons in the intra-cluster medium or to thermal-bremsstrahlung emission by an optically thin plasma at - 10s K.

A new survey of the southern sky for pulsars is being carried out jointly by the University of Sydney and the CSIRO Division of Radiophysics. J. M. Durdin, M. I. Large and A. G. Little from Sydney University have been working with R. N. Manchester, J. H. Taylor and myself from Radiophysics. This paper provides a brief description of the experiment and an account of progress to date.

We present observations of Hα and CaII resonance lines in 4 stars having Hα features which place them intermediately between the non-(e) and (e) classifications of dK/dM stars. There is considerable variety in the shape of the Hα line, presumably due in part to differences in rotation rates. As expected, the energy fluxes in the CaII emission lines lie between those typical of non-(e) and (e) stars. There is some evidence (especially from the binary Gl 876A) that the energy fluxes in the CaII and Hα emission lines do not vary from star to star according to a simple proportionality. An intriguing result is the apparent detection of spatially displaced chromospheric emission in Gl 907.1 and Gl 890.

The term ‘flare continuum’ (denoted by FC) was introduced by Wild (1970) to describe a strong, stationary continuum source at the metre wavelengths which occurs early in some flare events, particularly those of high energy. The flare continuum is distinct from the ‘storm continuum’ (SC), which occurs late in some flare events, becomes strongly circularly polarized and may continue as a ‘storm’. Both had previously been referred to as ‘stationary type IV’ bursts, to distinguish them from the original ‘moving type IV’ burst, IVM.

The most extensive studies of supernova remnants (SNRs) in the past have taken place at radio and optical wavelengths.

Recent two-dimensional observations of the quiet sun at 80 MHz by Sheridan showed a persistent low-intensity source (radio enhancement) whose daily motion was consistent with a source at radius 0.95 R® rotating with a synodic period of 27.3 d. In this paper we shall attempt to interpret this result in terms of the effects of refraction and opacity in model coronas. Comprehensive studies of the Sun at 169 MHz show that similar radio enhancements are associated with coronal streamers and that reasonable values for electron density and temperature within the coronal streamer allow the observations to be explained in terms of thermal radiation. Hence we shall consider only coronal models that possess streamer structure. We shall show that temperature enhancements within the streamer (‘thermal model’) do not lead to an apparent radius as small as that observed by Sheridan and that his observation may be better understood in terms of a non-thermal model for radiation from the streamer region.

Cas A has a radio surface brightness much higher (by a factor of about 100) than that of any other galactic supernova remnant (SNR) and is probably the youngest (≤ 300 yr). It therefore provides unique information on young remnants, but this very uniqueness makes it hazardous to treat Cas A as a typical remnant. However, because it (i) shows a clearly defined shell of radio emission of much the same type as older remnants, and (ii) lies approximately on the extrapolation of the Σ.-D (surface brightness-diameter) relationship derived for older remnants (Clark and Caswell 1976); Caswell and Lerche 1979a), detailed comparison with older remnants seems appropriate.