As a pilot survey for the forthcoming 6dF Galaxy Redshift Survey, spectroscopy of galaxies selected in the 1.2 micron J waveband with the DENIS imaging survey was performed at the UKST using the FLAIR II multi-object spectroscope. Sixty-nine galaxy redshifts were obtained in a high galactic latitude field and an additional 12 redshifts in a low galactic latitude (b = 17˚), obscured field. This spectroscopic followup of NIR selected galaxies illustrates the feasibility of obtaining redshifts with optical spectra on galaxies selected at much longer wavelengths. It validated a very preliminary algorithm for star/galaxy separation for high galactic latitude DENIS objects, with 99% reliability for J <13.9. The FLAIR II redshifts are in excellent agreement with those, previously published, of 20 common galaxies. However, the FLAIR II redshift determinations presented here required substantially longer integration times to achieve 90% completeness than expected from previous optical surveys at comparable depth. This is mainly due to a degradation in overall fibre throughput due to known problems with ageing of the prism–cement–fibre interface with exposure to UV light. In comparison to our high galactic latitude field, our low latitude (high extinction) field required 2.5 times more exposure time for less than 50% of successful redshift measurements.

Among the J ≤ 13.9 galaxies with measured redshifts, only 376% display emission lines, in comparison with 60% of emission line galaxies in optical samples of comparable depth. These galaxies are, on average, half a magnitude bluer in B-J than galaxies of the same luminosity without emission lines. We confirm a previous optically-based result that the fraction of galaxies with emission lines increases rapidly with decreasing galaxy luminosity. The J band luminosity function is estimated. Our high latitude field displays a concentration of galaxies at cz ≲ 38 000 km s−1 suggesting a possible supercluster.A radial velocity is reported for a galaxy lying near the projected centre of the Abell 1434 cluster of galaxies, for which no cluster redshift is currently available.

Observations of the 21 cm line of neutral hydrogen can provide several integral properties of galaxies. The systemic velocity Vsvs indicates the distance Δ via the Hubble relation or through group membership. The integral over velocity of the flux density profile, ∫S dV, immediately yields the amount of neutral hydrogen in the galaxy: M H ∝ Δ2∫S dV (neglecting optical-depth effects). The profile width W and the inclination i (derived from the optical axial ratio), together with the (optical) angular diameter a, supply the ‘indicative mass’ Mi ∝ (W/sin i)2 a △ (Bottinelli et al. 1968; Balkowski 1973), which is a fair estimate of the total mass of the system. In addition, as shown by Tully and Fisher (1976), the profile width is a good indicator of luminosity L. The quantities and L, which are (at least roughly) representative of the amounts of matter and of gaseous and luminous material in the system, give an indication of its composition. Together with the linear diameter a△, these quantities contain clues as to galaxy formation and evolution.

This is the second of a series of papers presenting detailed optical spectra for QSOs and strong-emission-line galaxies identified with radio sources from a selected area (−15° to −23° in declination) of the Molonglo Reference Catalogue (MRC: Large et al. 1981). The catalogue is complete to 1 Jy at 408 MHz although it contains many weaker sources. First results were reported by Hunstead et al. (1978, Paper I) and a summary was given by Hunstead (1979). Results have also been given by White et al. (1980) for spectra of QSOs identified with radio sources to a much deeper level of 88 mJy from a small strip within the larger selected area.

Many of the important events in the life of a star occur, or are thought to occur, during the red giant or supergiant phase of evolution. For example, in heavy and intermediate mass stars supernova explosions terminate normal evolutionary processes while in lower mass stars the stellar envelope is entirely removed giving rise to planetary nebulae and, subsequently, white dwarfs. Theoretical calculations suggest that before the onset of these rather drastic events, a significant amount of nucleosynthesis occurs, giving rise to enhanced surface abundances of He, C, N and s-process elements (e.g., Iben and Truran 1978; Renzini and Voli 1981); loss of the envelope material by stellar winds, planetary nebula ejection and supernova explosions produce overall galactic enrichment in these elements.

We have extended our previous work to use the Murchison widefield array (MWA) as a non-coherent passive radar system in the FM frequency band, using terrestrial FM transmitters to illuminate objects in low Earth orbit (LEO) and the MWA as the sensitive receiving element for the radar return. We have implemented a blind detection algorithm that searches for these reflected signals in difference images constructed using standard interferometric imaging techniques. From a large-scale survey using 20 h of archived MWA observations, we detect 74 unique objects over multiple passes, demonstrating the MWA to be a valuable addition to the global Space Domain Awareness network. We detected objects with ranges up to 977 km and as small as $0.03$${\rm m}^2$ radar cross section. We found that 30 objects were either non-operational satellites or upper-stage rocket body debris. Additionally, we also detected FM reflections from Geminid meteors and aircraft flying over the MWA. Most of the detections of objects in LEO were found to lie within the parameter space predicted by previous feasibility studies, verifying the performance of the MWA for this application. We have also used our survey to characterise these reflected signals from LEO objects as a source of radio frequency interference (RFI) that corrupts astronomical observations. This has allowed us to undertake an initial analysis of the impact of this RFI on the MWA and the future square kilometer array (SKA). As part of this analysis, we show that the standard MWA RFI flagging strategy misses most of this RFI and that this should be a careful consideration for the SKA.

Large radio surveys such as those proposed for several SKA pathfinder and precursor telescopes require (automated) source-finding algorithms that are highly reliable, complete, and fast. Similarly, sophisticated visualisation tools are needed to explore the resulting survey data together with their multi-wavelength counterparts.

In this PASA Special Issue on Source Finding and Visualisation, several advanced source-finding algorithms, including novel methods for radio continuum, polarisation and spectral line surveys are described, tested and compared. The process of finding sources can be considered one of many important steps (e.g., pre-processing, source finding and characterisation, cataloguing/post-processing) in the production of astronomical source catalogues, on which much of the survey science is based.

The Australian SKA Pathfinder (ASKAP), equipped with novel Chequerboard phased array feeds, will be a powerful 21-cm survey machine. For the large volumes of ASKAP data, a special version of Duchamp, called Selavy, is being developed in consultation with the ASKAP survey science teams (Whiting & Humphreys 2012). Extensive testing and comparisons of existing and new source-finding algorithms were carried out for this PASA Special Issue and are presented by Westmeier, Popping & Serra (2012), Westerlund, Harris & Westmeier (2012), Popping et al. (2012), Huynh et al. (2012), Hollitt & Johnston-Hollitt (2012), Walsh et al. (2012), George, Stil & Keller (2012), Marsh & Jarrett (2012), Allison, Sadler & Whiting (2012) and Jurek & Brown (2012). An overview on spectral line source finding and visualisation is given by Koribalski (2012), while Hassan, Fluke & Barnes (2012) look into real-time 3D volume rendering of large (Tbytes) astronomical data cubes.

Fixes are presented to be applied to the Véron-Cetty and Véron Quasar Catalogue, 13th edition. These are comprised of 39 de-duplications, 380 astrometric moves of 8 + arcsec of which 31 are over 10 arcmin, and 30 indicated de-listings.

By applying a display ecology to the Deeper, Wider, Faster proactive, simultaneous telescope observing campaign, we have shown a dramatic reduction in the time taken to inspect DECam CCD images for potential transient candidates and to produce time-critical triggers to standby telescopes. We also show how facilitating rapid corroboration of potential candidates and the exclusion of non-candidates improves the accuracy of detection; and establish that a practical and enjoyable workspace can improve the experience of an otherwise taxing task for astronomers. We provide a critical road test of two advanced displays in a research context—a rare opportunity to demonstrate how they can be used rather than simply discuss how they might be used to accelerate discovery.

A total of 18 radio sources selected on the basis of steep low-frequency radio spectra have been searched for the presence of millisecond pulsars using the Molonglo Observatory synthesis telescope. The search covered pulsar periods down to 2 ms with a limiting sensitivity of approximately 10 mJy. No pulsars were detected.

While Centaurus A (NGC 5128) is not a particularly powerful radio galaxy, its proximity (˜ 5 Mpc) permits us to obtain linear resolution an order of magnitude better than can be obtained for the more powerful, distant radio galaxies. Thus one can hope to make meaningful comparisons between the morphologies seen over the electromagnetic spectrum from γ-rays to metre waves. This should lead to a more complete understanding of the energy production mechanisms and evolutionary histories of these objects.

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.

Here, we derive a Parker-wind-like solution for a stratified, plane-parallel atmosphere undergoing photoionisation. The difference compared to the standard Parker solar wind is that the sonic point is crossed only at infinity. The simplicity of the analytic solution makes it a convenient test problem for numerical simulations of photoevaporation in protoplanetary discs.

We present broadband photoelectric light curves for the RS CVn type star PZ Telescopium for 1980, 1982 and 1983. The photometric period is about 0.943 days. The V light curve shows radical changes in form and range over a few months, and may be continuously variable. B and V data were obtained in 1982 and 1983. In 1982 no (B-V) change with phase was detected. However, in the first part of the 1983 observing season, a (BV) change of around 0.02 magnitude was found. Also at this time, maximum light was some 0.05 magnitude above that measured previously. Our preliminary spectroscopic data obtained in 1983 indicate that PZ Tel is a double lined binary whose components are of approximately equal luminosities, but this is yet to be confirmed. We suggest that the photometric variations are due to the presence of large cooler starspots on the photosphere of one or both components, as seems to be the case for related systems. The rapid changes in the observed light curve imply equally rapid changes in the distribution of the starspots, and make this an interesting object for further study.

The radio emission associated with SN 1987A appears to be synchrotron emission resulting from the acceleration of electrons at the interface between the outward moving shock wave and clumps of circumstellar material. The Australia Telescope Compact Array is now able to resolve this region, which has dimensions of ~ arcsec, revealing a slight (10%) asphericity in the distribution of the low density gas within the [OIII] circumstellar ring. Assuming that the radio emission arises from a region just behind the shock front, we deduce a mean radial expansion velocity, from 1987 to 1992, of 29 200 kms. First observed contact of the shock with the [OIII] circumstellar ring could occur as early as mid-1993, depending on the deceleration in the intervening gas. This will probably be closely followed by shock-excited optical lines, a strong X-ray outburst and a further increase in the radio emission.

The paraboloid primary mirror of a classical reflecting telescope gives an image that is perfectly corrected for spherical aberration and free from chromatic aberration. However, the image suffers from coma, astigmatism and field curvature. These aberrations severely limit the usable field. For example, the primary mirror of the 200 inch telescope gives an acceptable image of a field with a diameter of only ~2’ arc.

Detailed physical mechanisms responsible for excitation of spectral lines in gaseous nebulae have been known for 50 years, and reasonable estimates of nebular densities and temperatures were obtained in the late thirties and early forties. However quantitative chemical analyses have proven difficult partly because of uncertainties in atomic parameters (notably collision strengths) and partly because of complications posed by the nebulae themselves.

This paper examines recent investigations of emission-line filaments along the edge of the radio source in Centaurus A. It shows how these studies have ramifications for the excitation of the narrow line regions and extended emission-line regions of other active galaxies.

An early-type, massive, short-period ($P_{\text{orb}}=2^d.310951$) eclipsing spectroscopic binary DN Cas has been re-visited with new spectral and photometric data. The masses and radii of the components have been obtained as $M_1=19.04\pm 0.07\,\text{M}_\odot$, $M_2=13.73\pm 0.05\,\text{M}_\odot$ and $R_1=7.22\pm 0.06\,\text{R}_\odot$, $R_2=5.79\pm 0.06\,\text{R}_\odot$, respectively. Both components present synchronous rotation ($V_{\text{rot}1}=160\,\text{km } \text{s}^{-1}$, $V_{\text{rot}2}=130\ \text{km} \,\text{s}^{-1}$) with their orbit. Orbital period analysis yielded a physically bound additional component in the system with a minimum mass of $M_3=0.88\,\text{M}_\odot$ orbiting in an eccentric orbit (e = 0.37 ± 0.2) with an orbital period of P12 = 42 ± 9 yr. High precision absolute parameters of the system allowed us to derive a distance to DN Cas as 1.7 ± 0.2 kpc which locates the system within the borders of the Cas OB6 association (d = 1.8 kpc). The space velocities and the age of DN Cas are in agreement with those of Cas OB6. The age of DN Cas (τ = 3–5 Myr) is found to be 1–2 Myr older than the embedded clusters (IC 1795, IC 1805, and IC 1848) in the Cas OB6 association, which implies a sequential star formation in the association.

The ionised gas regions, which are the main tracers of the spiral arms, can be used for the study and determination of the spiral structure of our Galaxy. Towards this goal, the Marseille Observatory elaborated and developed an instrument, using a scanning Fabry–Perot interferometer, particularly suited for the observation of extended objects. A survey of the southern Galactic plane then started at the beginning of 1990. The major instrumental aim is to obtain spectral information, and therefore the ionised gas kinematics, in each pixel of the observed fields. Already 300 fields of 38′×38′ have been observed in Hα with a spatial resolution of 9″×9″, covering almost the entire fourth quadrant of the Galactic plane, and numerous discrete HII regions have been detected, as well as diffuse emission which is widely distributed. Also, the Magellanic Clouds have been studied using the same instrument.

Roche (1850) made the first study of the stability of binary systems. The problem he studied, and which now bears his name, is concerned with the stability of a liquid star in a synchronous, circular orbit about a point mass. Roche’s calculations predicted that if the separation between the liquid star and the point mass is S2.5rs’/3, where r is the unperturbed radius of the liquid star and s the ratio of the mass of the point to the mass of the liquid star, then the liquid star would be unstable. This result was generalised to two liquid stars orbiting each other by Darwin (1910, p. 436). Using the tensor virial method Chandrasekhar (1969) has given a uniform analysis of the classical result. The classical results have been extended by Hachisu and Eriguchi (1984a, b) who looked for the onset of instability in polytropes in binary orbits.