Swinburne Astronomy Online (SAO) is an online graduate program in astronomy intended particularly for amateur astronomers, science communicators and educators. SAO emphasises the development of conceptual understanding and good communication skills in astronomy. The use of asynchronous discussion forums is a central feature of SAO. These 'online tutorials' were introduced partly with the intention of breaking down the isolation of distance education, but mainly to provide a venue where students could deepen their conceptual understanding of astronomy and hone their science communication skills while discussing course material with other students and instructors.

In this project aspects of the use of discussion forums in SAO were investigated, with comparisons made between average marks awarded for discussion forum contributions and those awarded for other assessment tasks, plus analysis of the rate at which students post to the forums, and an investigation of whether gender makes a significant difference to participation rate and assessment results. Responses by students to surveys that probe their ability to express themselves and communicate with classmates in this online form of distance education are discussed. Finally, possible implications for the use of discussion forums as a supplement to face-to-face teaching in astronomy are explored.

Type II and III solar radio bursts are associated with shock waves and streams of energetic electrons, respectively, which drive plasma waves and radio emission at multiples of the electron plasma frequency as they move out from the corona into the interplanetary medium. Analogous plasma waves and radiation are observed from the foreshock region upstream of Earth's bow shock. In situ spacecraft observations in the solar wind have enabled major progress to be made in developing quantitative theories for these phenomena that are consistent with available data. Similar processes are believed responsible for radio emissions at 2–3 kHz that originate in the distant heliosphere, from where the solar wind interacts with the local interstellar medium. The primary goal of this paper is to review the observations and theories for these four classes of emissions, focusing on recent progress in developing detailed theories for the plasma waves and radiation in the source regions. The secondary goal is to introduce and review stochastic growth theory, a recent theory which appears quantitatively able to explain the wave observations in type III bursts and Earth's foreshock and is a natural theory to apply to type II bursts, the outer heliospheric emissions, and perhaps astrophysicalemissions.

Radio observations of linear polarisation provide a useful probe of the physical conditions in the gaseous environments of compact steep spectrum (CSS) sources. Here, we present polarimetric VLBA observations at 8.4 GHz of the CSS quasar 3C 43. The jet in this source curves gently up to about 220 mas from the core, at which point it bends sharply, probably due to a jet–cloud encounter. Regions of polarised emission are detected along the jet, while the core component shows no significant polarisation.

The HI Parkes Zone of Avoidance Survey is a 21 cm blind search with the multibeam receiver on the 64-m radiotelescope, looking for galaxies hidden behind the southern Milky Way. The first, shallow (15 mJy rms) phase of the survey has uncovered 107 galaxies, two-thirds of which were previously unknown. The addition of these galaxies to existing extragalactic catalogues allows the connectivity of a very long, thin filament across the Zone of Avoidance within 3500 km s−1 to become evident. No local, hidden, very massive objects were uncovered. With similar results in the north (the Dwingeloo Obscured Galaxies Survey) our census of the most dynamically important HI-rich nearby galaxies is now complete, at least for those objects whose HI profiles are not totally buried in the Galactic HI signal. Tests are being devised to better quantify this remaining ZOA for blind HI searches. The full survey is ongoing, and is expected to produce a catalogue of thousands of objects when it is finished.

The radio–far infrared correlation is one of the tightest correlations found in astronomy. Many of the models explaining this correlation rely on the association of global magnetic field strength with gas density. In this letter we put forward that the physical reason for this association lies within the processes of magnetohydrodynamic turbulence.

We have extended our published set of low-mass AGB stellar modelsto lower metallicities. Different mass-loss rates have been explored. We provide interpolation formulae for the luminosity, effective temperature, core mass, mass of dredge up material and maximum temperature in the convective zone generated by thermal pulses. Finally, we discuss the resultant modification of these quantities when we use an appropriate treatment of the inward propagation of the convective instability, as caused by the steeprise in radiative opacity when the convective envelope penetratesthe H-depleted region.

The UK Schmidt Telescope (UKST) of the Anglo-Australian Observatory (AAO) has just embarked on a new Hα survey of the Southern Galactic Plane, Magellanic Clouds and selected regions using a specially designed, high-specification, monolithic, interference filter. It is probably the largest of its kind for astronomy. It is being used in combination with Kodak Tech Pan film-based emulsion. This emulsion not only has a useful sensitivity peak at Hα but also possesses extremely fine grain and an exceptionally high DQE for the hypersensitised product (∼10%). This leads to excellent imaging, sensitivity and low noise. It is clear that CCDs cannot yet match the wide-area coverage, uniformity and resolution of the UKST/Tech Pan combination for undertaking such a survey. The survey will initially include about 233 Galactic Plane and 40 Magellanic Cloud fields on 4-degree centres and will take about 3 years to complete. Some preliminary images from the new survey are presented and compared with the best previously available from the UKST. Examples of the first survey discoveries, new resolved Galactic planetary nebulae, are also given. This survey will have an unprecedented combination of area coverage, depth and resolution, superior to those of any previous optical survey of ionised gas in the Galaxy. Many new discoveries and research avenues are expected.

We present an application of Mathematical Morphology (MM) for the classification of astronomical objects, both for star/galaxy differentiation and galaxy morphology classification. We demonstrate that, for CCD images, 99.3 ± 3.8% of galaxies can be separated from stars using MM, with 19.4 ± 7.9% of the stars being misclassified. We demonstrate that, for photographic plate images, the number of galaxies correctly separated from the stars can be increased using our MM diffraction spike tool, which allows 51.0 ± 6.0% of the high-brightness galaxies that are inseparable in current techniques to be correctly classified, with only 1.4 ± 0.5% of the high-brightness stars contaminating the population. We demonstrate that elliptical (E) and late-type spiral (Sc-Sd) galaxies can be classified using MM with an accuracy of 91.4 ± 7.8%. It is a method involving fewer ‘free parameters’ than current techniques, especially automated machine learning algorithms. The limitation of MM galaxy morphology classification based on seeing and distance is also presented. We examine various star/galaxy differentiation and galaxy morphology classification techniques commonly used today, and show that our MM techniques compare very favourably.

Preliminary site testing results at Dome C (Antarctica) are presented, using both Automatic Weather Station (AWS) meteorological data (1986–1993) and Precipitable Water Vapour (PWV) measurements made by the authors. A comparison with the South Pole and other sites is made. The South Pole is a well established astrophysical observing site, where extremely good conditions are reported for a large fraction of time during the year. Dome C, where Italy and France are building a new scientific station, is a potential observing site in the millimetre and submillimetre range. AWS are operating at both sites and they have been continuously monitoring temperature, pressure and wind speed and direction for more than ten years. Site testing instruments are already operating at the South Pole (AASTO, Automated Astrophysical Site-Testing Observatory), while light experiments have been running at Dome C (APACHE, Antarctic Plateau Anisotropy CHasing Experiment) during summertime. A direct comparison between the two sites is planned in the near future, using the AASTO. The present analysis shows that the average wind speed is lower at Dome C (∼1 ms−1) than at the South Pole (∼2 ms−1), while temperature and PWV are comparable.

We present evidence for an anti-correlation between faint QSOs and B < 23 galaxies.A sample of 192 QSOs in a 2.5 deg2 area has been imaged using the Isaac Newton Telescope Wide-Field Camera. The cross-correlation signal is of a similar amplitude to the galaxy auto-correlation function at the limit of B < 23, but is negative in sign. As fainter galaxies are selected the negative correlation signal becomes less significant, until the signal is effectively zero at B < 26. We propose two alternate explanations for the observed effect. The first is gravitational lensing of the faint background QSOs, which have a flat number count slope. However, the lensing signal is significantly higher than expected in conventional models. The second possibility is that inter-galactic dust absorption is responsible. A reddening of only E(B - V) ≃ 0.02 is required to produce the observed correlation. The large 2dF and SDSS QSO surveys should allow a definitive solution to the question of QSO–galaxy correlations.

I would like to begin by saying what a pleasure it is for me to be here. For my entire adult life I have wanted to come to Australia. Actually, I have been invited to visit here twice before, but each time I was thwarted by circumstances beyond my control. But this time I was determined to (a) prove that the third time is indeed the charm, and (b) pay homage to Walter Stibbs, who in my mind is the epitome of a scholar and a gentleman. I have known Walter as colleague, teacher, and friend, not to mention as an inspiration, both professional and personal. So I am here today to try to give some sense of progress in the study of stellar atmospheres, a field that Walter has graced with his virtuosic touch. I will follow an unabashedly personal path, describing the development as I experienced it. I will focus almost entirely on early-type stars, where we may reasonably expect the atmospheric layers to be homogeneous, and in radiative equilibrium. Only at the end will I mention our nearest stellar neighbor, the Sun, which, because we can study it in so much detail, offers counterexamples to almost all of the the theory that works so well for early-type stars. I offer apologies in advance to anyone this approach may offend.

Optically, the Zone of Avoidance (ZOA) can only be explored to within a few degrees of the Galactic Equator. This restriction does not apply to radio wavelengths where we are able to detect galaxies at great distances behind the Galactic Plane. Using the Parkes 21 cm multibeam instrument we have detected neutral hydrogen (HI) in 42 galaxies in the region of the Great Attractor. We have been able to identify nine galaxies and make positional associations with a further six from existing optical catalogues, which makes at least 60% of these galaxies new discoveries.

In this paper we present a new method for obtaining the optical wavelength-dependent reddening function of planetary nebulae (PN), using the nebular and stellar continuum. The data used was a spectrum of NGC 6302 obtained using the Double Beam Spectrograph on the 2.3 m telescope at Siding Springs Observatory over three nights. This resulted in a spectrum covering a wavelength range 3300–8600 Å with a large dynamical range and a mean signal to noise of >102 Å−1 in the nebular continuum. With such a high S/N the continuum can be accurately compared with a theoretical model of nebular plus stellar continuum. The nebular electron temperature and density used in the model are determined using ratios of prominent emission lines. The reddening function can then be obtained from the ratio of the theoretical and the observed continuum. In the case of NGC 6302, it is known that much of the reddening arises from dust within or around the nebula, so that any differences between the measured reddening law and the 'standard' interstellar reddening law will reflect differences in the nebular grain size distribution or composition. We find that for NGC 6302, the visible to IR extinction law is indistinguishable from 'standard' interstellar reddening, but that the UV extinction curve is much steeper than normal, suggesting that more small dust grains had been ejected into the nebula by the PN central star. We have detected the continuum from the central star and determined its Zanstra temperature to be of order 150,000 K. Finally, using the extinction law that we have determined, we present a complete dereddened line list of nearly 600 emission lines, and report on the detection of the He(2–10) and He(2–8) Raman features at λ4331 Å and λ4852 Å, and the detection of Raman scattered O VI features at λ6830 Å and λ7087 Å. We believe this to be the first detection of this process in a PN.

In blazar models both protons and electrons may be efficiently accelerated in jets and produce γ-rays. Here we discuss the interactions of these γ-rays with different radiation fields. The external radiation fields within a few parsecs from the black hole involved in such interactions could be the direct radiation from the accretion disk coupled with the jet, the infrared radiation from a dusty torus, and the emission line radiation from the broad line region surrounding the accretion disk. The optical thickness for absorption of γ-ray photons in the external radiation fields is analysed for blazars and quasars.

Based on the unification theory of active galactic nuclei we briefly review the evidence for the existence of small scale dust tori in blazars/FR I. We propose that the existing jet–accretion disk symbiosis extrapolates to a large scale symbiosis between other important dusty constituents of the blazar/FR I family.

Our R-band data show that the optical light from Malin 1 corresponds well with the >2-arcmin extent of the galaxy's Hı content and continues well beyond previously published V-band optical light radial profiles. Analysis of our image yields improved understanding of the galaxy's properties. We measure ellipticity of 0.20 ± 0.03, implying inclination of 38 ± 3°, and we trace the radial profile to 77arcsec. A single dusty spiral arm is also weakly discernable, and is consistent with the rotation direction of the Hı and spiral structure of the inner disk. Possible scenarios for the origin of the spiral structure are discussed.

We present three Virtual Observatory tools developed at the Australia Telescope National Facility (ATNF) for the storage, processing and visualization of Australia Telescope Compact Array (ATCA) data. These are the Australia Telescope Online Archive, a prototype data-reduction pipeline, and the Remote Visualization System. These tools were developed in the context of the Virtual Observatory and were intended to be both useful for astronomers and technology demonstrators. We discuss the design and implementation of these tools, as well as issues that should be considered when developing similar systems for future telescopes.

There is now evidence that there may be a strong source of cosmic ray particles in the general direction of the Galactic Centre. The likelihood is that the observed particles are neutrons with energies of about 1018 eV. Associated with the production of those neutrons, we would expect that large numbers of charged cosmic rays would also be produced, and we investigate here the directional properties of those charged particles as they may be observed at the distance of the Earth from the Galactic Centre. We follow the propagation of such particles through a simple Galactic magnetic field model with both a turbulent and a regular field to determine what field properties most affect the observed beam. It appears that the turbulent field component is crucial to any resulting charged particle observations.

We present the design of, and a first analysis of data from, the atmospheric seeing monitor at the Australia Telescope Compact Array (ATCA). The seeing monitor has been operational almost continuously since 2004 May and every 10min delivers a measurement of the atmospheric phase stability at the observatory. Its measurements can be used by observers to help in deciding whether it is worth carrying out observations at millimetre wavelengths or whether a longer-wavelength backup project should be observed. We present a statistical analysis of the data recorded since 2004 September to characterize the annual variations in atmospheric path length fluctuations. Our analysis shows that in terms of phase stability, nights in spring, summer, and autumn are as good as, or better than, days in winter. We also find that the data imply that the turbulence in the lower few hundred metres of the atmosphere is predominantly responsible for the atmospheric seeing.