AAT/WFI optical images of a candidate extragalactic HI cloud, HIPASS J1712–64, are presented. The g and r band CCD mosaic camera frames were processed using a new data pipeline recently installed at the AAO. The resultant stacked images reach significantly deeper levels than those of previous published optical imaging of this candidate, providing a detection limit Mg ˜ −7 at a distance of 3 Mpc, the inferred distance to HIPASS J1712–64. However, detailed analysis of the images fails to uncover any stellar population associated with the HI emission. If this system is a member of the Local Group then it is pathologically different to other members. Hence, our observations reinforce earlier suggestions that this HI cloud is most likely Galactic in origin and not a Local Volume dwarf galaxy.

Type Ic supernovae can be classified as normal supernovae Ic, type Ic super-luminous supernovae, X-ray flash-connected supernovae, broad-line supernovae Ic, and gamma-ray burst-connected supernovae. Here we suggest an inner connection for all kinds of supernovae Ic which is based on whether a pair of jets are successfully launched: a normal supernovae Ic is a normal core collapsar without jets launched; a gamma-ray burst-associated supernovae Ic is a core collapsar with relativistic jets launched and successfully breaking out the envelope of the progenitor; an X-ray flash-associated supernovae Ic is a core collapsar with jets launched but can only develop a relativistic shock breakout; a broad-line supernovae Ic is an off-axis gamma-ray burst or an X-ray flash-associated supernova; and a type Ic super-luminous supernovae is close to the X-ray flash-connected supernovae Ic, but the shock breakout is not relativistic and most of the jet energy is deposited into the supernova component. Based on the luminosity-distance diagram, we derived the luminosity function of all different types of supernovae Ic as a whole. We also show that the normal supernovae Ic and gamma-ray burst-connected supernovae Ic have similar accumulative distributions.

We present a modified TREE-SPH code to model galaxies in three dimensions. The model includes a multi-phase description of the interstellar medium which combines two numerical techniques. A diffuse warm/hot gas phase is modelled by SPH, whereas a cloudy medium is represented by a sticky particle scheme. Interaction processes (such as star formation and feedback), cooling, and mixing by condensation and evaporation, are taken into account. Here we apply our model to the evolution of a Milky Way type galaxy. After an initial stage, a quasi-equilibrium state is reached. It is characterised by a star formation rate of ∼1 M⊙ yr–1. Condensation and evaporation rates are in balance at 0.1–1 M⊙ yr–1.

We present high-resolution observations of nearby ($z\lesssim0.1$) galaxies that have hosted Type Ia supernovae to measure systemic spectroscopic redshifts using the wide field spectrograph (WiFeS) instrument on the Australian National University 2.3 m telescope at Siding Spring Observatory. While most of the galaxies targeted have previous spectroscopic redshifts, we provide demonstrably more accurate and precise redshifts with competitive uncertainties, motivated by potential systematic errors that could bias estimates of the Hubble constant ($H_0$). The WiFeS instrument is remarkably stable; after calibration, the wavelength solution varies by $\lesssim$0.5 Å in red and blue with no evidence of a trend over the course of several years. By virtue of the $25\times 38$ arcsec field of view, we are always able to measure the redshift of the galactic core, or the entire galaxy in the cases where its angular extent is smaller than the field of view, reducing any errors due to galaxy rotation. We observed 185 southern SN Ia host galaxies and measured the redshift of each via at least one spatial region of (a) the core and (b) the average over the full-field/entire galaxy. Overall, we find stochastic differences between historical redshifts and our measured redshifts on the order of $\lesssim10^{-3}$ with a mean offset of 4.3${\times 10^{-5}}$ and normalised median absolute deviation of 1.2${\times 10^{-4}}$. We show that a systematic redshift offset at this level is not enough to bias cosmology, as $H_0$ shifts by $+0.1$ km s$^{-1}$ Mpc$^{-1}$ when we replace Pantheon+ redshifts with our own, but the occasional large differences are interesting to note.

Anovel profile detection method is proposed for astronomical fiber spectrum data with low signalto-noise ratio. This approach can be applied to the pretreatment for 2-D astronomical spectrum data before the extraction of spectra. The Wigner bispectrum, a classical higher-order spectrum analysis method, is introduced and applied to deal with the spectrumsignal in this article.After analyzing the Wigner higher-order spectra distribution of the target profile signal, the combination of the Wigner bispectrum algorithm and the fast Fourier transform algorithm is used to weaken the effect of the noise to obtain more accurate information. Both the reconstruction method of the Wigner bispectrum and inverse fast Fourier transform are used to acquire the detection signal. At the end of this paper, experiments with both simulated and observed data based on the Large Sky Area Multi-Object Fiber Spectroscopy Telescope project are presented to demonstrate the effectiveness of the proposed method.

One of the two main telescopes at Sydney Observatory is a computer-controlled 35.6-cm Celestron. It is used with a television-type system. There is an integrating CCD camera available as well as an ordinary TV camera for bright objects. The images from the cameras can be shown in the Observatory’s lecture room. They are first put through an image processor which allows constant enhancement, spatial filtering and the recording of images for use on cloudy nights. Preliminary results are encouraging, and show the value of the system, even in Sydney’s highly light-polluted sky.

We have found strong evidence for an abrupt decline in the HI rotation curve of the isolated spiral galaxy NGC 157. Various mass models to account for this, and the implications for the dark matter content of NGC 157, are discussed.

The Molonglo Observatory synthesis telescope has been used to obtain twelve observations of a 23′ arc field containing the active star AB Dor. On each occasion, an unresolved source close to the optical position of AB Dor was observed. The source exhibits day-to-day variations of flux density, with a mean value of ∼4 mJy. The identification of the source with the star and the variations in emission are discussed.

The origin of cylindrically symmetric supernova remnants (SNR) is discussed. The results of numerical simulations of the two best examples of barrel-like SNRs, SN 1006 and G296.5+10.0, are presented.

The Molonglo fan-beam survey is a digitized survey carried out in March and April 1966, using the 1 mile E-W arm of the Molonglo cross operating at 408 MHz. Three 1´.5 fan beams separated by 1´.5 in right ascension were used. The survey covered the region in right ascension from 10h30m to 18h30m and in declination from +18° to —40°. The region common to the 4C survey has been analysed and we have obtained right ascensions for the 4C sources.

Recently the possibility has been raised of using general relativistic star clusters as models for quasi-stellar sources. The theory of static, spherically symmetric, collisionless star clusters has been developed within the framework of general relativity. In particular, analogues have been found of the Newtonian polytropic models and of Woolley’s truncated Maxwellian systems. However, in view of the importance of rotation on stability in relativistic astrophysical problems, it is of considerable interest to include the effect of rotation in relativistic stellar dynamics.

A standard procedure for the simulation of galaxies is to replace the ∼ 1011 stars by ∼ 104 particles. These particles are assumed to have equal mass and their distribution in space produces a mass density ϱ which mimics the average mass density of the stars. From the mass density of the particles the gravitational forces between the particles can be computed. In the literature two methods have been used to compute these forces.

A summary of the main results from the 2dF Galaxy Redshift Survey of over 221 000 galaxies on the galaxy luminosity function and its dependence on surface brightness, spectral type, environment, and local density.

We present here the results from a full polarisation study, an important VLBI capability, of a selected set of bright Active Galactic Nuclei (AGNs), along with the steps required to fully calibrate the Australian Long Baseline Array. We compare strategies for high-precision polarisation measurements using two polarisation correction methods: (1) Linear model and (2) Ellipticity-Orientation model and two data-recording techniques: recording (1) nominally circular polarisation at all stations and (2) mixed polarisation, where all but one station record circular polarisation and the other recorded linear polarisation. The latter is corrected post-correlation. We explored these possible solution to discover which will best accommodate the heterogeneous nature of the Australian Long Baseline Array without impacting on the science results. The targets, all compact and of low polarisation fraction, allow us to compare multiple independent solutions for polarisation characteristics. The results show that the agreement between the two polarisation correction models is excellent. However, the values from Mopra with nominally circular polarisation are larger than would be acceptable. However, we also demonstrate that recording mixed polarisation modes and correcting post-correlation provide a high quality polarisation product. We report on the detailed tests of these strategies and assess that the array is ready for full polarisation operation.

In this talk I shall start by describing how we set about and carried out the work that led to the publication of Burbidge et al. (1957, hereafter B2FH). I then shall try and relate this work and the circumstances that surrounded it to the larger problem of the origin and formation of the universe. Here it is necessary to look back at the way that ideas developed and how, in many situations, astronomers went astray. Of course this is a personal view, though I very strongly believe that if he were still here, it is the approach that Fred Hoyle would take.

I start by describing the problems originally encountered by Gamow and his associates in trying to decide where the helium was made. This leads me to a modern discussion of the origin of 2D, 3He, 4He and 7Li, originally described by B2FH as due to the x-process. While it is generally argued, following Gamow, Alpher, and Herman, that these isotopes were synthesised in a big bang I shall show that it is equally likely that these isotopes were made in active galactic nuclei, as was the cosmic microwave background (CMB), in a cyclic universe model. The key piece of observational evidence is that the amount of energy released in the conversion of hydrogen to helium in the universe is very close to the energy carried by the CMB, namely ∼4.5 × 10−13 erg cm−3.

An attempt is made to deduce the form taken by the distribution law for radiative scattering events performed by an atom whose energy—level structure is perturbed under conditions appropriate to the quasi-static limit.

A 3 GHz maser from the Onsala Space Observatory, Sweden, is currently at Parkes on a long-term loan basis. So far, it has been used on the 64-m radio telescope for a two-week period of spectral-line observations in February 1979, providing a system sensitivity far superior to that previously available at the same frequency. The observed lines were the ground-state transitions of CH at 3264, 3335 and 3349 MHz, the 211 – 212 transition of H2CS at 3139 MHz, and the 211-212 transition of CH3CHO at 3195 MHz.

We present observations of Hα and CaII resonance lines in 4 stars having Hα features which place them intermediately between the non-(e) and (e) classifications of dK/dM stars. There is considerable variety in the shape of the Hα line, presumably due in part to differences in rotation rates. As expected, the energy fluxes in the CaII emission lines lie between those typical of non-(e) and (e) stars. There is some evidence (especially from the binary Gl 876A) that the energy fluxes in the CaII and Hα emission lines do not vary from star to star according to a simple proportionality. An intriguing result is the apparent detection of spatially displaced chromospheric emission in Gl 907.1 and Gl 890.

We present the results of investigation of five stars, originally classified as dwarfs, belonging to Cyg OB2 association, their stellar, and wind properties. Using both tlusty and cmfgen codes, we derived effective temperatures, surface gravities, chemical abundances, mass-loss rates, and projected rotation velocities. Due to the fact that distance to the stars is well known, we were able to estimate their luminosities. Using evolutionary models, we estimated the ages of these sample stars and find that lower mass ones—MT282 and MT343—belong to older population of the association. Their ages are greater than 10 Myr. The ages of three other stars—MT317, MT299, MT259—are between 4 and 6 Myr.

In wavelength calibration using arc lines, the normal approach is to use the strongest unsaturated lines, leaving weak lines unused. A new method is proposed in this paper, which not only utilizes the strong spectral lines, but also makes most use of weak spectral lines. In order to validate the effectiveness of the method we propose, experiments are performed on simulated spectra. Firstly, two kinds of spectra are generated: one with a short exposure and another with a long exposure. Secondly, calibration lines are chosen from the short exposure and long exposure spectra separately according to some rules. Thirdly, the initial wavelength calibration is completed by using the selected short-exposure lines. Fourthly, the approximate centroids of the selected long-exposure lines are obtained by utilizing the result of the initial wavelength calibration. These are then adjusted iteratively to obtain the centroids. Finally, the selected lines from the short- and long-exposures are combined to obtain the final wavelength calibration. Compared with traditional calibration methods which only use short exposures and strong lines, the proposed method is shown to be more accurate.