The Australia Telescope Compact Array has been used in two 6 km configurations to make 12 hour observations of the radio continuum structure of three spiral galaxies at 1380 MHz and 2378 MHz. Radio maps of NGC 1792, 6300 and 1097 are presented here, as part of a survey to find examples of anomalous radio structures in spiral galaxies.

The propagation of extragalactic particles within our Galaxy has been modelled. The flux of such particles is below the observed cosmic ray flux at most energies when their power-law spectrum is extrapolated back from the highest energies. Also, we expect that the propagation of extragalactic particles through static magnetic fields in the Galaxy will not result in a flux change to match the flux of particles measured here within the Galaxy. However, if we were to consider the observed cosmic rays to be of Galactic origin, there would be a remarkable similarity between the required Galactic injection flux and the extrapolated extragalactic flux. We consider here whether the scattering of extragalactic particles in the Galaxy together with an associated energy perturbation might be sufficient for the extragalactic beam to result in the production of ‘Galactic’ particles and, hence, essentially all of the observed cosmic rays. This appears to be possible.

We have used a sample of 263 Parkes half-Jansky flat-spectrum radio sources to measure the spatial correlation function of radio galaxies and radio-loud quasars on scales up to 1000 h−1 Mpc. We do not detect any clustering in the sample. If any undetected clustering is described by a power-law spatial correlation function [ξ(r) = (r/r0)−1·8], we can rule out clustering with scales r0 ≥ 50 h−1 Mpc at the 99·9% confidence level. We have also used the sample to test for the ‘possible’ large concentration of quasars in the direction of the microwave background dipole found by Shaver (1987). There is no evidence for such a concentration in our data and we show that the earlier result was probably biased by the use of non-uniform image classifications.

A simple model is presented for electron acceleration in extragalactic radio sources with two hot spots. The effect of diffusive shock acceleration by multiple shocks is calculated numerically, with adiabatic and synchrotron losses included. It is found for the sources 3C 20 and 3C 268·4 that a consistent set of model parameters exists which reproduce the observations. The model fails to reproduce the observations for the source 3C 196.

The possibility is considered that core emission in pulsars results from secondary e± pairs generated through linear acceleration emission (LAE), rather than the conventional curvature emission (CE). It is found that this is possible in principle, but only under conditions that appear not to be satisfied in practice.

Expressions for the probability per unit time of the emission of a Langmuir wave by both massive and massless neutrinos moving in a medium are derived using finite-temperature field theory. A comparison between this process and the analogous emission from an electron is made, and possible implications of this process for the explosion mechanisms of type II supernovae are briefly discussed.

Zeeman Doppler Imaging (ZDI) is a recent technique for measuring magnetic fields on rapidly rotating, active stars. ZDI employs spectropolarimetry taken at different rotational phases to derive information on the magnetic field distribution over the stellar surface. The Zeeman effect is used to identify the presence of a magnetic field, and variations in Doppler wavelength shifts across the rapidly rotating star allow fields to be resolved on different parts of the visible disk. Analysis of the spectra can be used to produce both thermal and surface magnetic images. ZDI requires very high S/N spectra to be acquired within a time interval short compared to the stellar rotation period. As a result, a large-aperture telescope is needed. Since an initial successful test in 1989, the 3·9 m Anglo-Australian Telescope has been used to obtain ZDI spectra of active stars of different evolutionary stages. The observations have concentrated on the K subgiant in the RSCVn system HR 1099 to monitor changes on this bright and active star. With the advent in 1991 of ZDI spectropolarimetry with the AAT échelle spectrograph, it has become possible to co-add the polarisation signature from the many magnetically sensitive lines recorded simultaneously. As a result, stellar magnetic field detections of unprecedented quality have been obtained. The aims of this paper are to briefly outline the principles of ZDI, describe the instrumental setup at the AAT and present some preliminary results from recent observations.

Following a successful program to investigate the physics of ultra-high-pressure proportional counters, a counter array has been developed for hard X-ray astronomy. A parallel investigation has evaluated the performance of a large-area phoswich scintillator detector for the same purpose. The two detectors have been integrated in a balloon-borne payload, the Astrophysical X-ray Experimental Laboratory (AXEL). This paper describes the instrumentation aboard the payload.

An outline is given of the main research programs currently in progress at the Carter Observatory. These include: the establishment of a set of standard star magnitudes and colours in the Vilnius seven-colour photometric system; the study of galactic and extragalactic star clusters using Vilnius and broadband photometries; binary stars and the development of APTs; and the history of Australasian astronomy. The role of Carter Observatory Honorary Research Associates is described and mention is made of the joint New Zealand/Japan program to observe gravitational microlensing effects, discover variable stars and patrol selected clusters of galaxies for supernovae.

This paper outlines the extensive range of public programs offered by the Carter Observatory, including ‘public nights’, new planetarium and audio-visual shows, displays, the Carter Memorial Lectures, the annual Astronomical Handbook and other publications, a monthly newspaper column and three monthly radio programs. It also deals with the Observatory’s involvement in undergraduate and postgraduate astronomy at Victoria University of Wellington, various adult education training programs, ‘Overnight Extravaganzas’, holiday programs, and the recent development of the Education Service in response to the introduction of an astronomy curriculum into schools throughout New Zealand. Some possible future developments in the public astronomy and education areas are also discussed.

Computers and the Internet have created a revolution in the way astronomy can be communicated to the public. At Sydney Observatory we make full use of these recent developments. In our lecture room a variety of sophisticated computer programs can show, with the help of a projection TV system, the appearance and motion of the sky at any place, date or time. The latest HST images obtained from the Internet can be shown, as can images taken through our own Meade 16 in telescope. This recently installed computer-controlled telescope, with its accurate pointing, is an ideal instrument for a light-polluted site such as ours.

A Millimetre-wave Astronomy Workshop was held at the CSIRO Radiophysics Laboratory in Marsfield, Sydney, on 19 April 1995. The workshop, sponsored by the Australia Telescope National Facility (ATNF), was a meeting of mm-wave specialists as well as astronomers and students interested in the field, and attracted about 80 participants from 13 institutions. The program consisted of 23 oral contributions (5–45 min) followed by lively discussions. Abstracts of most of the contributions are presented here, arranged by groups dealing with subjects such as ‘A Basic Introduction’, ‘Astronomy in the mm-range with Mopra’ and ‘Projects: Galactic and Extragalactic 3 mm-wave astronomy’.

The 3 mm radio continuum emission from active galaxies consists of three components:

1. (1) Synchrotron emission from the active galactic nucleus (AGN), which is over 1 Jy in 3C273 but which is not significant in most of the types of galaxy considered here.

2. (2) Free–free emission from H II regions. The flux of this in a starburst galaxy is typically of the order of 10 mJy and could be imaged with a 3 mm-capable Australia Telescope Compact Array (ATCA).

3. (3) Emission from the tail of the 50–100 K black-body spectrum of the dust. For example, the dust in Arp 220 (redshift of 0·02) at a temperature of 50 K has a flux of 30 mJy at 3 mm. Interestingly, this flux does not decrease substantially with redshift, as the decrease in brightness is compensated for by the redshifting of the steep edge of the blackbody curve, and so infrared-bright galaxies can be studied up to high redshifts with existing instruments.

We have recently discovered evidence for a population of radio-loud quasars that is reddened by dust. The dust is either along the line of sight to the quasars or is associated with the quasars. In the latter case the dust may be in molecular clouds in the quasar’s host galaxy, or in a molecular torus around the nucleus. We are planning to use 3 mm observations to search for molecular absorption lines (CO and HCO+) associated with dust at the redshift of these quasars. If any absorption systems are detected we will be able to deduce detailed information about the physical state of the molecular gas, hopefully showing which of the proposed locations of the dust is most likely.

Radio emission at centimetre and millimetre wavelengths provides a powerful tool for studying the circumstellar envelopes of evolved stars. These include stars on the asymptotic giant branch (AGB), post-AGB stars and a small number of massive M-type supergiant stars. The AGB stars and M-type supergiants are characterised by extremely high mass-loss rates. The mass loss in such an evolved star is driven by radiation pressure acting on grains which form in the outer stellar atmosphere. The grains are accelerated outwards and transfer momentum to the gas through grain–gas collisions. The outflowing dust and gas thus form an expanding circumstellar envelope through which matter flows from the star to the interstellar medium, at a typical velocity of 15 km s−1. For a recent review of circumstellar mass loss see Chapman, Habing & Killeen (1995).

There are several excellent reasons for studying the Magellanic Clouds at millimetre wavelengths with a telescope such as the AT Mopra antenna:

• The Magellanic Clouds are the nearest young, gas-rich galaxies to the Galaxy. They are therefore ideal places to study the processes which lead to star formation, and for comparing these processes with Galactic processes.

• The distances of the Clouds are well established at close to 50 kpc for the LMC and 60 kpc for the SMC.

• The Mopra beam at 2·6 mm (CO) corresponds to ~10 pc, which is comparable with the size of molecular clouds and complexes in the LMC and SMC (e.g. Rubio et al. 1993). The Mopra beam is also complementary to that obtainable at low frequencies with the AT Compact Array for continuum and HI studies (e.g. the 750 m configuration at 21 cm will give a resolution of ~12pc).

The thermal emission from a cold, dense molecular cloud peaks in the far IR, and the spectrum is rich in molecular lines in the submillimetre and millimetre bands. Observation of these bands is hindered, however, by atmospheric water vapour, which absorbs the incoming radiation. Ground-based mm observations from Australia, where the atmospheric water vapour content typically contains ~10 mm precipitable (ppt) H2O, can only probe a few of the molecular transitions from the heavier molecules, such as CO, CS, HCO+ and HCN. Sub-mm observations would enable the higher rotational lines from many of these molecules to be studied, and open up other spectral features to scrutiny, such as the lines from hydrides (e.g. CaH, NH, SH) and neutral carbon at 370 and 610 μm. However, they cannot be made from Australia. While sites such as Mauna Kea, which has ~1 mm ppt H2O on the best days, open the sub-mm band to partial viewing, their utility is limited in comparison to the opportunities possible from the Antarctic Plateau. Here the column of H2O drops to 100–250 μm.

I look briefly at protostellar environments and at what information can be gained from the millimetre waveband. A short overview of the theory of protostellar environments and evidence of disks will be followed by a more detailed review of recent publications of observations of protostellar halos/disks, specifically in 3 mm.

A condensed summary of molecular cloud astrophysics is presented. Some examples of the power of combining near-IR and mm molecular line observations are given.

A program to observe millimetre-wave molecular transitions in a number of southern-sky molecular clouds is under way. Molecular clouds in both the Galaxy and the Magellanic Clouds are included in the sample. The aim of the program is to build a body of observational data which can be used to derive molecular abundances in southern-sky molecular clouds.