Determination of the large-scale structure of flare-produced disturbances requires either multiple spacecraft observations or an ensemble averaging of single spacecraft observations of a number of events. There is currently some confusion in the results of studies of shock normals derived from spacecraft data. Chao and Lepping (1974) suggest that the average shock shape near 1 AU is essentially spherical while Bavassano et al. (1973) suggest that the disturbance corresponds closely to the shapes predicted in the numerical simulations of de Young and Hundhausen (1971).

This paper presents recent stellar evolutionary calculations of the Asymptotic Giant Branch evolution of a 5M ⊙ model. It is found that temperatures at the base of the convective envelope reach up to almost 100 million degrees, high enough for much nucleo-synthesis to occur. Some implications are discussed briefly.

We describe a versatile infrared camera/spectrograph, IRIS, designed and constructed at the Anglo-Australian Observatory for use on the Anglo-Australian Telescope. A variety of optical configurations can be selected under remote control to provide several direct image scales and a few low-resolution spectroscopic formats. Two cross-dispersed transmission echelles are of novel design, as is the use of a modified Bowen-Burch system to provide a fast f/ratio in the widest-field option. The drive electronics includes a choice of readout schemes for versatility, and continuous display when the array is not taking data, to facilitate field acquisition and focusing.

The linearity of the detector has been studied in detail. Although outwardly good, slight nonlinearities prevent removal of fixed-pattern noise from the data without application of a cubic linearising function.

Specific control and data-reduction software has been written. We describe also a scanning mode developed for spectroscopic imaging.

The AAT’S new IR array camera, IRIS, has been used to image the Galactic Centre in the He I (2.058μm), H+ Br γ(2.166μm) and H2 1-0 S(l) (2.122μm) emission lines. The case is presented for UV-excitation of the molecular gas, as opposed to shocks.

One of the factors determining system sensitivity in radio astronomy measurements of microwave emission and absorption spectra is the flatness of the spectrometer response in the absence of any spectral features. Ripple appears as a quasi-sinusoidal variation of this baseline and occurs whenever two or more components of the same signal reach the receiver by different paths and interfere.

In theories of the heating of the solar corona a number of authors have recently considered the propagation and damping of fast and slow magnetohydrodynamic waves, in the form of surface waves localized on the interfaces of coronal flux tubes (Ionson 1978, Wentzel 1979, Roberts 1981, Cramer and Donnelly 1983). The damping of these waves occurs, in addition to a rather weak global damping due to viscous or resistive dissipation, by means of a localized absorption at a so-called ‘resonance’ in the density or magnetic field profile forming the flux tube. At such a resonance, the wave frequency is equal to the local value of the Alfven wave frequency, in the case of Alfven resonance absorption, or at the local slow mhd wave frequency, in the case of the ‘cusp’ or ‘compressive singularity’ resonance in a finite pressure plasma.

We have measured the 2.3 GHz total and correlated flux densities on a baseline of 275 km of all sources in the Parkes catalogue which

1. (i) are south of declination +10°,

2. (ii) have a catalogued 2.7 GHz total flux density exceeding 0.5 Jy, and

3. (iii) have a 2.7/5.0 GHz spectral index flatter than −0.5.

More than 14% of the sample showed visibility amplitudes greater than 0.9, and more than 72% showed visibility amplitudes greater than 0.5. Of the sources with optical or other identifications 79% were quasars. In this paper we briefly summarise the results of this survey.

There has been considerable speculation in recent years about the evolution of radio galaxies in clusters. The discovery of powerful X-ray emission with an apparently thermal spectrum from a considerable number of clusters has been attributed to a hot (108K) intracluster gas with an electron density of ∼ 10-3 cm -3 at the cluster centre (see e.g. McHardy 1978). Such a gas surrounding a radio galaxy may conceivably retard the expansion or diffusion of the relativistic electrons and thus allow the source to retain its identity for longer intervals than is the case for field galaxies.

A major crisis facing theoretical nuclear astronomers and physicists today is the apparently very low flux of neutrinos emitted by the Sun. Davis et al. report a measurement of 1.5 ± 1 s.n.u. (1 s.n.u. = 10−36 capture/Cl37/sec) which is a factor of 6 or so smaller than the theoretically predicted values. Numerous suggestions, often quite bizarre, have been made to account for the low flux, but so far no convincing explanation has been offered – see Fowler.

This paper summarises the function of the Inter-University Centre for Astronomy and Astrophysics in India.

The atmosphere of a star presents a real challenge to the astronomer or physicist. We can observe but the thinnest skin of the star; yet from the information obtained therefrom we must deduce the star’s temperature, chemical composition, its rotation (if any), the state of agitation in its outer layers, and eventually the surface gravity, total luminosity, mass, and evolutionary stage.

Polytropic models have played a significant part in the historical development of stellar structure theory and in other related branches of theoretical astronomy such as stellar pulsations and rotation. In modern astronomy polytropic solutions, because of their wide range of density distributions and our ability to introduce them analytically if necessary, now have an acknowledged role in large scale numerical experiments especially during the developmental stages.

The question of modelling a wide variety of astrophysical phenomena is discussed. It is argued that the combination of new computing equipment and algorithms has created the opportunity for a concerted attack on problems ranging from star formation to the evolution of the universe.

In 1975, Hoessel, Elias, Wade and Huchra commenced a near infrared survey of 80 fields in the northern Milky Way with the Palomar 1.2 m Schmidt telescope, (Hoessel et al. 1979). This has now been issued as an atlas reproduced in the form of photographic paper prints. In 1977, the SRC 1.2 m Schmidt telescope at Siding Spring was authorized to commence a complementary survey of the southern Milky Way, consisting of the 151 ESO/SRC survey fields which have centres within 10° of the galactic plane and negative declinations (see Fig. 1). A further 12 fields have subsequently been added to the survey to permit coverage of the Large and Small Magellanic Clouds.

A recent analysis of the spectra of about 2000 sources in the Culgoora-3 list (Slee 1977) of radio sources (Slee et al. 1981) has revealed some interesting features which may be the result of source evolution. The Culgoora-3 spectra were obtained by combining the 80 and 160 MHz flux densities from the Culgoora radioheliograph with other published flux data between 10 and 10,000 MHz; this is probably the most accurate set of spectra yet derived for a large number of sources selected for observation in a reasonably consistent manner. In addition to fitting the log S-log v data for each source with a straight line (its slope is the usual definition of spectral index) Slee et al. also fitted second-degree and third-degree polynomials to search for curvature in the spectra.

The Molonglo Observatory Synthesis Telescope (MOST), which at present images a fully synthesised 70′ field in 12 h, is being converted to enable observing modes which extend the field size to 160′. The new observing modes will allow the MOST to survey completely the sky south of δ = −30° to a (5σ) sensitivity limit of about 5 mJy. The result will be a catalogue of over 400,000 radio sources with a spatial density of less than 1 source per 100 beam areas, providing the foundation for a number of novel astronomical and cosmological investigations. The conversion involves construction of 352 low-noise HEMT preamplifiers, 88 digitally controlled UHF quad phase shifters, 88 mixers and IF sections, a new communication and control system, and several other new sub-systems. The project has been funded and developments are well advanced.

The only planet with observed secular motion between the body and the axis of rotation is the Earth itself, which rotates both progressively and with unexplained librations about equatorial axes.