An instrument is described that can detect clouds at night-time by sensing their infrared emission. The device can readily detect clouds that are difficult to see with the unaided eye on a moon-lit night. It can be used to provide an indication of how photometric the conditions are, to terminate exposures when cloud forms, and to close the dome when conditions become unsuitable for observing. The detector also has applications as an astronomical site-surveying instrument.

It has long been known that Fraunhofer lines show variations in intensity from place to place over the Sun’s surface, these being particularly noticeable in spectroheliograms obtained in the strong chromospheric lines. An early account of the weaker Unes was given by d’Azam-buja. McMath, Mohler, Pierce and Goldberg attributed intensity increases in (or decreases in depth of) metallic spectral lines to local temperature increases. Sheeley used high-resolution spectra to study these line weakenings further, finding them where, and only where, strong non-spot magnetic fields occurred. He also reported that in many cases the continuum in such regions was of reduced intensity, suggesting that fields often occur in the dark lanes and pores in the granulation. Spectroheliograms obtained in the cores of the weakened lines (e.g., Fel 6302.5Å) by Chapman and Sheeley showed that the bright network which these weakenings form appears as a sequence of sharp, bright points in the cores of the fainter lines and the wings of stronger lines but is more diffuse in the cores of stronger lines. They found the bright network in Zeeman-insensitive Unes (e.g., 5123.7A) also, indicating that it is due, at least in part, to variations in physical conditions. Lines of low ionization and excitation are weakened more than those of high ionization and excitation, and they attributed this to a temperature increase by 100-200 °K in the region of formation of the line cores ; a similar increase of 250 °K was found by Harvey and Livingston.

A software package called ERIC is described that provides a framework for allowing scientific instruments to be remotely controlled via the Internet. The package has been used to control four diverse astronomical instruments, and is now being made freely available to the community. For a description of ERIC’s capabilities, and how to obtain a copy, see the conclusion to this paper.

In addition to large numbers of normal galaxies, the multibeam HI Parkes all-sky survey will probably discover intergalactic HI clouds, very low-surface-brightness, gas-rich galaxies, and small HI clouds in nearby groups of galaxies. I will briefly discuss some aspects of why these classes of objects are interesting in the context of dark matter and galaxy formation.

In this paper, the hypothesis of the existence of a massive dark body (Nemesis, Tyche, Planet Nine, or any other trans-Plutonian planet) at the Solar system periphery is analysed. Basic physical properties and orbital characteristics of such massive bodies are considered. The problem of the definition of a scattering angle of a photon in the gravitational field of a spherical lens is studied. It is shown that, the required value of the scattering angle can be measured for the cases of Nemesis and Tyche. The formation of gravitational lensing images is studied here for a point mass event. It is demonstrated that in most cases of the close rapprochement of a source and the lens (for Nemesis and Tyche), it is possible to resolve two images. The possibility of resolving these images is one of the main arguments favouring the gravitational lensing method as its efficiency in searching for dark massive objects at the edge of the Solar System is higher than the one corresponding to other methods such as stellar occultation. For the cases of Planet Nine and any other trans-Plutonian planet, the strong gravitational lensing is impossible because at least one of the images is always eclipsed.

The Two Micron All-Sky Survey (2MASS) has provided a uniform photometric catalog to search for previously unknown red active galactic nuclei (AGN) and Quasi-Stellar Objects (QSOs).We have extended the search to the southern equatorial sky by obtaining spectra for 1182 AGN candidates using the six degree field (6dF) multifibre spectrograph on the UK Schmidt Telescope. These were scheduled as auxiliary targets for the 6dF Galaxy Redshift Survey. The candidates were selected using a single color cut of J – Ks > 2 to Ks ≲ 15.5 and a galactic latitude of lbl > 30°. 432 spectra were of sufficient quality to enable a reliable classification. 116 sources (∼27%) were securely classified as type I AGN, 20 as probable type I AGN, and 57 as probable type II AGN. Most of them span the redshift range 0.05 < z < 0.5 and only 8 (∼6%) were previously identified as AGN or QSOs. Our selection leads to a significantly higher AGN identification rate amongst local galaxies (>20%) than in any previous (mostly blue-selected) galaxy survey. A small fraction of the type I AGN could have their optical colors reddened by optically thin dust with AV < 2 mag relative to optically selected QSOs. A handful show evidence of excess far-infrared (IR) emission. The equivalent width (EW) and color distributions of the type I and II AGN are consistent with AGN unified models. In particular, the EW of the [Oiii] emission line weakly correlates with optical–near-IR color in each class of AGN, suggesting anisotropic obscuration of the AGN continuum. Overall, the optical properties of the 2MASS red AGN are not dramatically different from those of optically-selected QSOs. Our near-IR selection appears to detect the most near-IR luminous QSOs in the local universe to z≃0.6 and provides incentive to extend the search to deeper near-IR surveys.

It is evident that the limited duration of a single rocket or balloon flight is a severe handicap to the study of variable X-ray sources like Cen XR-2, the early history of which can only be conjectured from the few available rocket observations. The whole question of the variability of X-ray sources remains in doubt because of the difficulty of relating infrequent high-altitude flux measurements of short duration made with a variety of instruments. There are obvious advantages in a method of monitoring celestial X-ray fluxes from the ground for prolonged periods of time. Such a method has recently been found and, although presently restricted to strong sources like Sco XR-1 and Cen XR-2, is capable of considerable refinement.

Solar metre-wave noise storms commonly show continuum and short-lived narrow-band bursts (Type I) at high frequencies and fast-drift bursts (Type III) at low frequencies (Malville 1962; Hanasz 1966; Boischot et al. 1970; Moller-Pedersen 1974; see also Figs. 2-3 of this paper). The Type I and Type III emissions have the same sense of polarization (Komesaroff 1958; Suzuki 1978). Impressed by this spectral association, Malville (1962) and Boischot et al. (1970) suggested that the two types of emission might be excited by the same electron stream. However, Type I emission is associated with sunspots and strong photospheric magnetic fields (McCready et al. 1947; Payne-Scott and Little 1951; Le Squeren 1963) and for this reason Kai (1970) suggested that Type I emission arises on strong closed magnetic loops. Type III emission, by contrast, almost certainly arises on open or quasi-open (large-loop) magnetic field lines (Wild et al. 1959, 1963). Thus on these models one would expect Type I and Type III emissions to arise from different magnetic regimes and different areas of the Sun. Kai’s (1970) and Stewart and Labrum’s (1972) Culgoora radioheliograph observations, which suggested that Type I and Type III sources are always separated on the Sun, seemed to clinch the matter. Kai’s model and his statement ‘Type III sources avoid the precise location of Type I storm centres’ gained wide acceptance (e.g. Boischot et al. 1971; Elgaroy 1977; Stewart 1977).

The strong unidentified radio source 1733-565 (≡ PKS 1733-56) was chosen as a test source during the commissioning of the Molonglo Observatory Synthesis Telescope (MOST) in 1981 July. Previous radio maps have been obtained at 1410 MHz with the Parkes interferometer (Schwarz et al. 1974), at 408 MHz with the Molonglo Cross (Schilizzi & McAdam 1975) and at 1415 MHz with the Fleurs Synthesis Telescope (Christiansen et al. 1977).

The European Southern Observatory Faint Object Spectrograph and Camera v2 is one of the workhorse instruments on ESO’s New Technology Telescope, and is one of the most popular instruments at La Silla observatory. It is mounted at a Nasmyth focus, and therefore exhibits strong, wavelength and pointing-direction-dependent instrumental polarisation. In this document, we describe our efforts to calibrate the broadband imaging polarimetry mode, and provide a calibration for broadband B, V, and R filters to a level that satisfies most use cases (i.e. polarimetric calibration uncertainty ~0.1%). We make our calibration codes public. This calibration effort can be used to enhance the yield of future polarimetric programmes with the European Southern Observatory Faint Object Spectrograph and Camera v2, by allowing good calibration with a greatly reduced number of standard star observations. Similarly, our calibration model can be combined with archival calibration observations to post-process data taken in past years, to form the European Southern Observatory Faint Object Spectrograph and Camera v2 legacy archive with substantial scientific potential.

Although scientific astronomy has a long and illustrious history in Australia, it was not until 1895 that the first astronomical society was formed. This was the New South Wales Branch of the British Astronomical Association (see B.A.A. 1894-5; Gale 1895a,b), and before the end of the century it was joined by others in Melbourne and Brisbane (B.A.A. 1897-8; Editor’s Note 1979; Ellery 1901:13; Thomson 1897). These societies and their predecessors, the Astronomy Branches of the Royal Societies of New South Wales and South Australia (Waters 1980), were the mainstay of astronomical activity – both professional and amateur – in nineteenth century Australia, providing as they did regular meetings, library facilities, and avenues for publication and celestial observation.

The Charles Sturt University Remote Telescope Project aims to make available to primary school students and their teachers a simple-to-use telescope and CCD camera set up over the Internet. Access to the telescope is supported by a 10 week curriculum unit of Astronomy activities. The telescope is not a robotic device. It is controllable in real time with images being transmitted to the user also in real time. Visitors to the site are able to view what is happening at the telescope without being able to take control of it. This paper describes the project, the software control system and the related curriculum activities. Discussion centres around how to ignite students' and teachers' interest in science and how projects such as this one may lead to more exciting coverage of important topics in the primary and lower secondary schools.

Observations of the distribution of millimetre-wavelength brightness over the quiet Sun provide an important test of models of the solar chromosphere. The author and colleagues have recently carried out two investigations of the quiet-Sun brightness at 3 mm wavelength — one by means of a total eclipse observation (Labrum et al. 1978) and the other by aperture synthesis with a two-element interferometer (Archer et al. 1978). I present here a preliminary discussion of these and other measurements of millimetre-wavelength brightness distributions and of their interpretation in terms of chromospheric structure.

Odd Radio Circles (ORCs) are a class of low surface brightness, circular objects approximately one arcminute in diameter. ORCs were recently discovered in the Australian Square Kilometre Array Pathfinder (ASKAP) data and subsequently confirmed with follow-up observations on other instruments, yet their origins remain uncertain. In this paper, we suggest that ORCs could be remnant lobes of powerful radio galaxies, re-energised by the passage of a shock. Using relativistic hydrodynamic simulations with synchrotron emission calculated in post-processing, we show that buoyant evolution of remnant radio lobes is alone too slow to produce the observed ORC morphology. However, the passage of a shock can produce both filled and edge-brightnened ORC-like morphologies for a wide variety of shock and observing orientations. Circular ORCs are predicted to have host galaxies near the geometric centre of the radio emission, consistent with observations of these objects. Significantly offset hosts are possible for elliptical ORCs, potentially causing challenges for accurate host galaxy identification. Observed ORC number counts are broadly consistent with a paradigm in which moderately powerful radio galaxies are their progenitors.

We present spectroscopic and photometric analysis of the eclipsing binary KIC 7385478. We find that the system is formed by F1V + K4III–IV components. Combining results from analysis of spectroscopic data and Kepler photometry, we calculate masses and radii of the primary and the secondary components as M1 = 1.71 ± 0.08 M⊙, M2 = 0.37 ± 0.04 M⊙ and R1 = 1.59 ± 0.03 R⊙, R2 = 1.90 ± 0.03 R⊙, respectively. Position of the primary component in HR diagram is in the region of γ Doradus type pulsators and residuals from light curve modelling exhibit additional light variation with a dominant period of ~ 0.5 d. These are clear evidences of the γ Doradus type pulsations on the primary component. We also observe occasional increase in amplitude of the residuals, where the orbital period becomes the most dominant period. These may be attributed to the cool star activity originating from the secondary component.

The atmospheric 14C record, the corresponding WM values derived from a carbon reservoir model, auroral numbers and the Zurich relative annual sunspot numbers all demonstrate a substantial downturn in solar activity for the duration of solar cycles 5 and 6. This reduction is also imbedded in some dendrochronological proxy data sets, which describe an annual index radial growth rate for trees at high-altitude sites. A significant lagged correlation can exist between tree-ring indices and the 11–year solar cycle during periods of high solar activity, a feature which is not evident during quiescent periods.

We have analysed the 2dF spectra of a sample of galaxies common to the 2dF Galaxy Redshift Survey (2dFGRS, Colless 1999) and the NRAO VLA Sky Survey (NVSS, Condon et al. 1998). Our sample comprises 88 galaxies selected by Sadler et al. (1999) from 30 2dFGRS fields observed in 1998. In this paper we discuss how this and future, much larger, samples of 2dFGRS–NVSS galaxies can be interpreted via analysis of those galaxies with strong narrow emission lines. Using diagnostic line ratio measurements, we confirm the majority of the eyeball classifications of Sadler et al. (1999), although many galaxies show evidence of being ‘composite’ galaxies—mixtures of AGN plus starburst components.

Starting from a sketch of the s-process concept formulated 50 years ago, the nuclear physics data for s-process calculations are briefly reviewed with emphasis on the status of neutron capture cross sections and beta decay rates. Accurate and comprehensive experimental data are mandatory as direct input for s-process calculations as well as for improving the complementary information from nuclear theory. The current challenges of the field are discussed in the light of new or optimized methods and state-of-the-art facilities, indicating the potential for accurate measurements and the possibility to study cross sections of radioactive isotopes. These opportunities will be considerably enriched by the enormous improvements provided by new facilities.

We compare the total flux density variations and the VLBI structural variations in a sample of 27 gamma-ray blazars. We find that all the radio variations are due to shocks; the flux of the underlying jet remains constant. A large fraction of the shocks grow and fade within the innermost 0.1 mas, appearing only as ‘core flares’. Comparisons with the EGRET data show that gamma-ray flares must come from the shocks, not from the jet. At the time of an EGRET flare, the shock is typically already over a parsec downstream from the radio core, beyond the accretion disk and/or the broad line region (BLR) photon fields. Thus, present models for gamma-ray production are inadequate, since they typically model the gamma-ray inverse Compton flux as coming from the jet, with significant disk or BLR external Compton components.

With the advent of large-scale surveys (i.e. Legacy Surveys) it is now possible to start looking beyond the galaxy luminosity function (LF) to more detailed statistical representations of the galaxy population, i.e multivariate distributions. In this review I first summarise the current state-of-play of the B-band global and cluster LFs and then briefly present two promising bivariate distributions: the luminosity–surface brightness plane (LSP) and the colour–luminosity plane (CLP). In both planes galaxy bulges and galaxy disks form marginally overlapping but distinct distributions, indicating two key formation/evolutionary processes (presumably merger and accretion). Forward progress in this subject now requires the routine application of reliable bulge–disk decomposition codes to allow independent investigation of these two key components.