We use the wide-field capabilities of the 2 degree field fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first 3 years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ks per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is z ~ 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the 3-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4-m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of the sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.

In coming years, Australia may find the need to build new optical telescopes to continue local programmes, contribute to global survey projects, and form a local multi-wavelength connection for the new radio telescopes being built. In this study, we refine possible locations for a new optical telescope by studying remotely sensed meteorological infrared data to ascertain expected cloud coverage rates across Australia, and combine these data with a digital elevation model using a geographic information system. We find that the best sites within Australia for building optical telescopes are likely to be on the highest mountains in the Hamersley Range in northwest Western Australia, while the MacDonnell Ranges in the Northern Territory may also be appropriate. We believe that similar seeing values to Siding Spring should be obtainable and with significantly more observing time at the identified sites. We expect to find twice as many clear nights as at current telescope sites. These sites are thus prime locations for future on-site testing.

A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40°, spanning longitudes 167° through 360°to 79° at b = 0°, plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg2. The brightness temperature sensitivity will be very good, typically σT≃ 1 K at resolution 30 arcsec and 1 km s−1. The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.

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.

It is an indisputable fact that solar magnetic fields are force-free in the corona, where force-free fields mean that current and magnetic fields are parallel and there is no Lorentz force in the fields. While the force-free extent of photospheric magnetic fields remains open, in this paper, we give its statistical results. Vector magnetograms (namely, Bx, By, and Bz in heliocentric coordinates) employed are observed by the Solar Magnetic Field Telescope at Huairou Solar Observing Station. We study and calibrate 925 magnetograms calibrated by two sets of calibration coefficients, which indicate the relation between magnetic fields and the strength of the Stokes spectrum and can be calculated either theoretically or empirically. The statistical results show that the majority of active region magnetic fields are not consistent with the force-free model.

The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST will exploit the wide-field survey capabilities of ASKAP to enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, radio supernovae, and orphan afterglows of gamma-ray bursts. In addition, it will allow us to probe unexplored regions of parameter space where new classes of transient sources may be detected. In this paper we review the known radio transient and variable populations and the current results from blind radio surveys. We outline a comprehensive program based on a multi-tiered survey strategy to characterise the radio transient sky through detection and monitoring of transient and variable sources on the ASKAP imaging timescales of 5 s and greater. We also present an analysis of the expected source populations that we will be able to detect with VAST.

The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.

We present an absolute magnitude calibration for red giants with the colour–magnitude diagrams of six Galactic clusters with different metallicities, i.e. M92, M13, M3, M71, NGC 6791, and NGC 2158. The combination of the absolute magnitudes of the red giant sequences with the corresponding metallicities provides calibration for absolute magnitude estimation for red giants for a given (g − r)0 colour. The calibration is defined in the colour interval 0.45 ≤ (g − r)0 ≤ 1.30 mag and it covers the metallicity interval −2.15≤[Fe/H]≤ +0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the interval −0.28 < ΔM ≤ +0.43 mag. However, the range of 94% of the residuals is shorter, −0.1 < ΔM ≤ +0.4 mag. The mean and the standard deviation of (all) residuals are 0.169 and 0.140 mag, respectively. The derived relations are applicable to stars older than 2 Gyr, the age of the youngest calibrating cluster.

Measurements of the optical turbulence profile above Siding Spring Observatory were conducted during 2005 and 2006. This effort was largely motivated by the need to predict the statistical performance of adaptive optics at Siding Spring. The data were collected using a purpose-built instrument based on the slope detection and ranging (SLODAR) method where observations of a bright double star are imaged by Shack–Hartmann taken with the Australian National University 24-inch and 40-inch telescopes. The analysis of the data yielded a model consisting of a handful of statistically prominent thin layers that are statistically separated into the ground layer (37.5, 250 m) and the free atmosphere (1, 3, 6, 9, 13.5 km) for good (25%), typical (50%), and bad (25%) observing conditions. We found that ground-layer turbulence dominates the turbulence profile with up to 80% of the integrated turbulence below 500 m. The turbulence tends to be non-Kolmogorov, especially for the ground layer with a power-law index of β ~ 10/3. The mirror/dome seeing can be a significant fraction of the ground-layer turbulence. The median atmospheric seeing is around 1.2 arcsec, in agreement with observational reports.

Using an observationally derived model of optical turbulence profile, we have investigated the performance of adaptive optics (AO) at Siding Spring Observatory, Australia. The simulations cover the performance for AO techniques of single-conjugate adaptive optics (SCAO), multi-conjugate adaptive optics (MCAO), and ground-layer adaptive optics (GLAO). The simulation results presented in this paper predict the performance of these AO techniques as applied to the Australian National University (ANU) 2.3-m and Anglo-Australian Telescope (AAT) 3.9-m telescopes for astronomical wavelength bands J, H, and K. The results indicate that the AO performance is best for the longer wavelengths (K band) and in the best seeing conditions (sub 1 arcsec). The most promising results are found for GLAO simulations (field of view of 180 arcsec), with the field RMS for encircled energy 50% diameter (EE50d) being uniform and minimally affected by the free-atmosphere turbulence. The GLAO performance is reasonably good over the wavelength bands of J, H, and K. The GLAO field mean of EE50d is between 200 and 800 mas, which is a noticeable improvement compared with the nominal astronomical seeing (870–1 700 mas).

We present two absolute magnitude calibrations, MJ and MKs, for red giants with the colour–magnitude diagrams of five Galactic clusters with different metallicities, i.e. M92, M13, M71, M67, and NGC 6791. The combination of the absolute magnitudes of the red giant sequences with the corresponding metallicities provides calibration for absolute magnitude estimation for red giants for a given colour. The calibrations for MJ and MKs are defined in the colour intervals 1.3≤(V−J)0≤2.8 and 1.75≤(V−Ks)0≤3.80 mag, respectively, and they cover the metallicity interval −2.15≤[Fe/H]≤+0.37 dex. The absolute magnitude residuals obtained by the application of the procedure to another set of Galactic clusters lie in the intervals −0.08<ΔMJ≤+0.34 and -0.10< Δ MKs≤ +0.27 mag for MJ and MKs, respectively. The means and standard deviations of the residuals are 〈ΔMJ〉=0.137 and σMJ=0.080, and $〈 Δ MKs〉 =0.109 and σMKs=0.123 mag. The derived relations are applicable to stars older than 4 Gyr, the age of the youngest calibrating cluster.

In this article, we present a galactic gravitational model of three degrees of freedom (3D), in order to study and reveal the character of the orbits of the stars, in a binary stellar system composed of a primary quiet or active galaxy and a small satellite companion galaxy. Our main dynamical analysis will be focused on the behaviour of the primary galaxy. We investigate in detail the regular or chaotic nature of motion, in two different cases: (i) the time-independent model in both 2D and 3D dynamical systems and (ii) the time-evolving 3D model. For the description of the structure of the 2D system, we use the classical method of the Poincaré (x, px), y = 0, py < 0 phase plane. In order to study the structure of the phase space of the 3D system, we take sections in the plane y = 0 of the 3D orbits, whose initial conditions differ from the plane parent periodic orbits, only by the z component. The set of the four-dimensional points in the (x, px, z, pz) phase space is projected on the (z, pz) plane. The maximum Lyapunov characteristic exponent is used in order to make an estimation of the chaoticity of our galactic system, in both 2D and 3D dynamical models. Our numerical calculations indicate that the percentage of the chaotic orbits increases when the primary galaxy has a dense and massive nucleus. The presence of the dense galactic core also increases the stellar velocities near the center of the galaxy. Moreover, for small values of the distance R between the two bodies, low-energy stars display chaotic motion, near the central region of the galaxy, while for larger values of the distance R, the motion in active galaxies is entirely regular for low-energy stars. Our simulations suggest that in galaxies with a satellite companion, the chaotic nature of motion is not only a result of the galactic interaction between the primary galaxy and its companion, but also a result caused by the presence of the dense nucleus in the core of the primary galaxy. Theoretical arguments are presented in order to support and interpret the numerically derived outcomes. Furthermore, we follow the 3D evolution of the primary galaxy, when mass is transported adiabatically from the disk to the nucleus. Our numerical results are in satisfactory agreement with observational data obtained from the M51-type binary stellar systems. A comparison between the present research and similar and earlier work is also made.

We present a study on characterising the light curves of W UMa-type systems gathered from the archive containing 5 years of data observed with the Robotic Optical Transient Search Experiment Telescope (ROTSE-IIId) located in Turkey. A sample of 45 W UMa-type systems was studied on the basis of Fourier decomposition of light curves and some basic geometrical parameters, namely degree of contact (f), mass ratio (q), and orbital inclination (i), as approximated values for these systems were determined. Moreover, methods based on the Fourier transform technique were applied to the discrete data to determine the orbital periods of those systems. Preliminary estimates for the system parameters were presented and compared with the values available in the literature.

The Gaia satellite, planned for launch by the European Space Agency (ESA) in 2013, is the next-generation astrometry mission following Hipparcos. Gaia’s primary science goal is to determine the kinematics, chemical structure, and evolution of the Milky Way Galaxy. In addition to this core science goal, the Gaia space mission is expected to discover thousands of Solar System objects. Because of orbital constraints, Gaia will only have a limited opportunity for astrometric follow-up of these discoveries. In 2010, the Gaia Data Processing and Analysis Consortium (DPAC) initiated a program to identify ground-based optical telescopes for a Gaia follow-up network for Solar System Objects to perform the following critical tasks: confirmation of discovery, identification of body, object tracking to constrain orbits. To date, this network comprises 37 observing sites (representing 53 instruments). The Zadko Telescope, located in Western Australia, was highlighted as an important network node because of its southern location, longitude, and automated scheduling system. We describe the first follow-up tests using the fast moving Potentially Hazardous Asteroid 2005 YU55 as the target.

The chemical abundances of the metal-poor stars in the stellar stream provide important information for setting constraints on models of neutron-capture processes. The study of these stars could gives us a better understanding of the r-process nucleosynthesis and chemical composition of the early Galaxy. Using the updated main r-process and weak r-process patterns, we fit abundances in the stellar stream stars. The weak r-process component coefficients are almost constant for the sample stars, including r-rich stars, which means that both the weak r-process and Fe are produced as primary elements from Type II supernovae and their yields have nearly a constant mass fraction. The difference between the stream stars and r-rich stars is obvious. For the stream stars, the fact that the increased trend in the main r-process component coefficients as metallicity increases means a gradual increase in the production of main r-process elements relative to iron. This behaviour implies that the masses of progenitors for the main r-process are smaller than those of the weak r-process. Furthermore, we find that the metal-poor stream star HD 237846 is a weak r-process star.

Taking into account the results obtained from the models and analyses of the BVRI light curves, we discuss the nature of V1464 Aql. The analyses indicated that the mass ratio of the system is q = 0.71 ± 0.02, while the inclination of the system (i) is 38°.45 ± 0°.22. Taking the primary component’s temperature as 7420 ± 192 K, we found that the temperature of the secondary is 6232 ± 161 K. The mass of the primary component was found to be 1.74 ± 0.05 M⊙, while it is 1.23 ± 0.01 M⊙ for the secondary. The primary component’s radius was found to be 2.10 ± 0.05 R⊙, while it was found as 1.80 ± 0.01 R⊙ for the secondary. Revealing that the system should not exhibit any eclipses, we demonstrated that the main variation with large amplitude should be caused due to the ellipsoidal effect. Indeed, the Fourier analysis also supported the result. For the first time in the literature, we revealed that the primary component is a δ Scuti star. The period of pulsation was found to be 58.482 ± 0.002, 58.482 ± 0.001, 60.966 ± 0.002, and 60.964 ± 0.003 min in BVRI bands, respectively. We plotted V1464 Aql in the log (Porb)–log (Ppulse) plane. Using more than 160 binaries, whose one or both components are pulsating, we derived a new linear fit in the log (Porb)–log (Ppulse) plane for each type of binary. Using the linear fit of each group, we obtained new calibrations between log (Porb) and log (Ppulse) for different types of pulsating stars. In addition, a calibration has been obtained for the first time for the pulsating stars with spectral types O and B. V1464 Aql seems to be located near the other ellipsoidal and close binaries. Thus, we listed V1464 Aql as a new candidate for the ellipsoidal variables with a δ Scuti component.

A ‘pulsar timing array’ (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of ‘global’ phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (~700 MHz), 20 cm (~1400 MHz), and 10 cm (~3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant ‘red’ timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an ‘extended PPTA’ data set that combines PPTA data with earlier Parkes timing data for these pulsars.

Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 7 , we explore influences of galaxy interactions on AGN activity. It is found that in the faint volume-limited sample, paired galaxies have a slightly higher AGN fraction than isolated galaxies, whereas in the luminous volume-limited sample, an opposite trend can be observed. The significance is <1σ. Thus, we do not observe strong evidence that interactions or mergers likely trigger the AGN activity.

In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia), e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals, and the technical challenges which are being addressed to maximise the science return.

The lowest frequency band (70–450 MHz) of the Square Kilometre Array (SKA) will consist of sparse aperture arrays grouped into geographically localised patches or stations. Signals from thousands of antennas in each station will be beamformed to produce station beams which form the inputs for the central correlator. Two-stage beamforming within stations can reduce SKA-low signal processing load and costs, but has not been previously explored for the irregular station layouts now favoured in radio astronomy arrays. This paper illustrates the effects of two-stage beamforming on sidelobes and effective area, for two representative station layouts (regular and irregular gridded tiles on an irregular station). The performance is compared with a single-stage, irregular station. The inner sidelobe levels do not change significantly between layouts, but the more distant sidelobes are affected by the tile layouts; regular tile creates diffuse, but regular, grating lobes. With very sparse arrays, the station effective area is similar between layouts. At lower frequencies, the regular tile significantly reduces effective area, hence sensitivity. The effective area is highest for a two-stage irregular station, but it requires a larger station extent than the other two layouts. Although there are cost benefits for stations with two-stage beamforming, we conclude that more accurate station modelling and SKA-low configuration specifications are required before design finalisation.