Propagation of 150 μs radio pulses (f= 1.91 MHz) along a magnetospheric field-aligned ionization duct have been observed, under conditions of low ionospheric critical frequency. The echoes, presumably reflected from the ionosphere at the magnetic conjugate point, were received at the transmitting site near Hobart. Positively identified echoes were observed on six separate occasions during periods of moderate solar activity, with delay times of approximately 260 ms, representing a value L = 2.95.

It has recently been reported (Cini-Castagnoli et al. 1973; Jacklyn and Cini-Castagnoli, 1974) that Jupiter may be responsible for a modulation component in the counting rate of underground cosmic ray detectors on the earth. The evidence suggests that a screening mechanism is operating, in as much as the observed counting rates are diminished when Jupiter is within the field of view of these detectors. The magnitude of the effect is larger than can be accounted for by simple line-of-sight obscuration by the planet itself, and it has been suggested that the intense and extensive Jovian magnetic field is producing the effect.

We conducted spectroscopic and photometric observations of the optical companion of the X-ray transient RX J0117·6–7330 in the Small Magellanic Cloud, during a quiescent state. The primary star is identified as a B0·5 IIIe with a mass M* = (18 ± 2)M⨀ and bolometric magnitude Mbol = –7·4 ± 0·2. The main spectral features are strong Hα emission, Hβ and Hγ emission cores with absorption wings, and narrow He I and O II absorption lines. Equivalent widths and full widths at half maximum of the main lines are listed. The average systemic velocity over our observing run is vr = (184 ± 4) km s−1; measurements over a longer period of time are needed to determine the binary period and the K velocity of the primary. We determine a projected rotational velocity v sin i = (145 ± 10) km s−1 for the Be star; if we assume a true rotational velocity at the equator v = (400 ± 50) km s−1, we deduce that the inclination angle of the system is i = (21 ± 3) deg.

Proxima Centauri was observed photoelectrically in the period July-September 1987 with a newly-installed computer-interfaced photometer. Four definite flares and six further possible events were recorded. The level of Proxima’s flaring activity was examined and no significant change since 1969 found.

A Photometrics CCD system containing a TH7882 chip has been in use at Mt John since 1989 October for imaging photometry. Extra control software has increased observing ease and image-header information. Photometrically the system appears to be performing satisfactorily. The blue helium star LSS 99 showed no variation exceeding ~ 1% over 40 min of observation. The blue eclipsing binary HV 1761 in the Small Magellanic Cloud is found to have approximately equal components.

Some while ago (Prentice 1973a) I demonstrated that if the present Sun were to possess a small burnt out central core of mass 2-3% M⊙ its neutrino flux would be a factor 10 or so smaller than that of conventional homogeneously evolved solar models. It was not, however, conclusively shown what conditions might lead to the formation of such a core or indeed whether a burnt out core could be attained after 4.7 × 109 yr. of nuclear evolution. In this connection Demarque et al. (1973) has considered the evolution of an initially inhomogeneous model consisting of a hydrogen free core surrounded by a homogeneous envelope.

A common test for hydrodynamic calculations is the Boss and Bodenheimer (1979, 1981, hereafter BB) problem in which an isothermal, spherical cloud of 1 M⊙ is given a cos (2Φ) density perturbation and the ensuing evolution studied.

The present Astronomy Advisory Committee (AAC) was set up by the then Minister for Science and the Environment, Senator J. J. Webster, in July 1979 following a Government review of astronomical facilities carried out by an interdepartmental committee (IDC) in 1978-1979. The IDC was assisted by an expert sub-committee, whose report Review of Observatories (1978) has since been published. The AAC consists of a chairman and ten members drawn from the astronomical community in Australia. It is serviced by the Department of Science and the Environment.

The eclipsing variable SV Cen was observed differentially in the UBV system with the 60cm reflector at Perth Observatory (1974-75) and with the 41cm reflector at Siding Spring (1975-79). Individual measurements have either been published in the IBVS or will be published there soon.

In recent years, cosmic-rays have become part of the study of astrophysics and the search for information as to their origin has assumed considerable importance. The question of the origin of the rays is linked with questions concerning their acceleration and propagation through interstellar space. The main problem facing the cosmic-ray astrophysicist in attempting to elucidate these questions observationally arises from the fact that most particles are electrically charged, causing their paths to be curved by the magnetic fields of the Earth and interplanetary and interstellar space.

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.

The polytropic stellar model with index n = 0 has a uniform density distribution throughout, and consequently its physical radius is essentially arbitrary because the surface density condition, ϱ = 0, is never satisfied. This surface anomaly, which is not associated with the other polytopic models for 0 < n ≤ 5, could be a constraining factor in certain astrophysical applications involving the n = 0 polytrope. For example, in some circumstances it may be appropriate to utilize the simple physical formulation of the model but on the other hand inappropriate to disregard any zero boundary requirements for the surface density. A sequence of new E-type (as defined below) composite analytical solutions to the Lane-Emden equation, based on the indices 0 and 1, has been developed which eliminates this physical indetermination. The associated polytropic models can be classified as essentially uniform density models. Specifically, they have a large central uniform density n = 0 zone matched, in a physically consistent way, to a small outer n = 1 zone which has a steep density gradient giving ϱ = 0, along with T = 0 and P = 0, at the radial distance corresponding to the first zero of the composite solution.

We report the results of Long Baseline Array observations made in 2001 of ten southern sources proposed by Mattox et al. as counterparts to EGRET >100 MeV gamma-ray sources. Source structures are compared with published data where available and possible superluminal motions identified in several cases. The associations are examined in the light of Fermi observations, indicating that the confirmed counterparts tend to have radio properties consistent with other identifications, including flat radio spectral index, high brightness temperature, greater radio variability, and higher core dominance.

An optical astronomical facility is being established near Hobart where the emphasis is being placed upon spectroscopy. A 40 cm telescope and Coudé spectrograph is already operational, and the 100 cm instrument will be operational by mid-1973. In this paper discussion is restricted to the 100 cm instrumentation.

An enormous effort is underway worldwide to attempt to detect gravitational waves. If successful, this will open a new frontier in astronomy. An essential portion of this effort is being carried out in Australia by the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA), with research teams working at the Australia National University, University of Western Australia, and University of Adelaide involving scientists and students representing many more institutions and nations. ACIGA is developing ultrastable high-power continuous-wave lasers for the next generation interferometric gravity wave detectors; researching the problems associated with high optical power in resonant cavities; opening frontiers in advanced interferometry configurations, quantum optics, and signal extraction; and is the world's leader in high-performance vibration isolation and suspension design. ACIGA has also been active in theoretical research and modelling of potential astronomical gravitational wave sources, and in developing data analysis detection algorithms. ACIGA has opened a research facility north of Perth, Western Australia, which will be the culmination of these efforts. This paper briefly reviews ACIGA's research activities and the prospects for gravitational wave astronomy in the southern hemisphere.

The use of roman numerals for stellar populations represents a classification approach to galaxy formation which is now well behind us. Nevertheless, the concept of a pristine generation of stars, followed by a protogalactic era, and finally the mainstream stellar population is a plausible starting point for testing our physical understanding of early star formation. This will be observationally driven as never before in the coming decade. In this paper, we search out observational tests of an idealised coeval and homogeneous distribution of population II stars. We examine the spatial distribution of quasars, globular clusters, and the integrated free electron density of the intergalactic medium, in order to test the assumption of homogeneity. Any real inhomogeneity implies a population II that is not coeval.

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⊙.

The pulsar 0833-45 associated with the Vela supernova remnant has been known as a strong source with fairly constant pulse amplitude since its discovery (Large, Vaughan & Mills 1968) using the east-west arm of the Molonglo telescope. The pulse stability together with the short period of 89 ms allowed its integrated flux to be seen also as a 1.7 Jy point source with the pencil beam of the full Cross, and a more precise declination was obtained. Further observations in 1971/72 with a beat period integrator used on the fan beams of the north-south arm showed that the pulsed radiation had the same declination as the point source within 2 arcsec (Vaughan & McAdam 1973). Monitoring observations in 1975/76 gave an independent position, and the mean of all Molonglo (408 MHz), Fleurs (1415 MHz) and NRAO interferometer (2700 MHz) positions led to the optical detection of the pulsar (Goss et al. 1977). The point source, therefore, is reliably identified with the pulsar.

Theoretical investigations of non-linear convective motions quite often assume that either the Boussinesq or the anelastic approximations can be used.

Observations of five cepheids in Crux are described and annual epochs of maxima presented. The O–C diagram of S Crucis shows changes between two alternative periods. The observing method appears suited to sites with only a limited number of hours available.