With the completion of the Hubble Space Telescope (HST) Key Project on the Extragalactic Distance Scale, it is interesting to form the dimensionless quantity H0t0 by multiplying the Hubble Constant by the age of the Universe. In a matter dominated decelerating Universe with a density exceeding 0·26 of the critical value, H0t0 < 1; in an accelerating Universe with the same Ωm = 0·26, but dominated by vacuum energy with ΩV ≥ 1 – Ωm, H0t0 ≥ 1. If the first globular clusters formed 109 years after the Big Bang, then with 95% confidence H0t0 =1·0 ± 0·3. The classical Einstein–de Sitter cosmological model has H0t0 = ⅔.

This paper investigates a recent model proposed by Moskalenko, Collmar & Schönfelder (1998) for the plasma surrounding galactic black hole candidates. Using a linear Monte Carlo code, the spectral and temporal behaviour of the model is found for the case where the plasma geometry consists of a hot shell surrounding a cooler spherical core. The spectrum produced by this model at X-ray and gamma-ray energies is obtained numerically. Also found for the first time in this geometry are the photon time-lags between two energy bands due to rapid aperiodic variability. It is argued that the time-lag information may be able to determine whether this particular geometry is a realistic model for the material surrounding galactic black hole candidates.

We discuss variations of the atmospheric extinction coefficients and transformation equations to the standard UBVRI system based on observations of standard stars during 1996–1997 at Siding Spring Observatory using a thinned SITe CCD and coloured glass filters. In the transformation from the initial natural system to the Landolt version of the standard system, a large nonlinear term related to the Balmer discontinuity was required for the U transformation. We then modified the U filter, and the subsequent transformation to the SAAO version of the standard UBVRI system had only small nonlinear correction terms for U, B, and I. The correction terms relating to U and B are evidently due to the Balmer discontinuity, while that relating to I seems to be due to the Paschen discontinuity at λ ≈ 8200 Å. We also compared the results with Landolt's observations, and confirmed the difference between the two sets of standard stars (SAAO and Landolt).

In the past few years the American Physical Society (APS) has conducted a number of surveys among the graduate student population in the US and also among young researchers. The purpose was to get an idea of the career expectations of the students and how these are met later on in their life. Two of the conclusions were: (1) students want to work in a research environment, preferably academic, and (2) graduate and undergraduate programs are not preparing them well for the different challenges and goals found in industry, the private sector and national laboratories. Jobs in academia, especially tenured positions, have been difficult to obtain forcing many students to give up on their goals after one or two postdoctoral positions. Some have found jobs in other sectors but others feel frustrated that their careers have not met their expectations and are poorly ‘prepared’ for other options. In the areas of Physics and Astronomy there is not much of a job market without graduate studies. So most students must continue graduate work, in these or other fields, in order to compete well in the job market. Graduate and undergraduate programs must become more responsible for the present state of affairs and for implementing improvements. This can be done by broadening the scope of the present programs so that a student is better prepared to face the challenges of other job opportunities. We present here a BSc program designed by astronomers and physicists, at the University of Guanajuato, to try to address some of these concerns and better prepare the students for either continuing with graduate studies or finding employment in an ever-changing job market.

The Antarctic Plateau provides the best terrestrial sites for infrared (IR) and submillimetre (sub-mm) astronomy. In this paper we examine the relative importance of temperature, aerosol content and precipitable water vapour to determine which parameters have the greatest influence on atmospheric transmission and sky brightness. We use the atmospheric modelling program MODTRAN to model the observed sky spectrum at the South Pole from the near-IR to the sub-mm. We find that temperature and aerosol content determine the quality of near-IR observing conditions, aerosol content is the determining factor in the mid-IR up to 20 μm, while at longer wavelengths, including the sub-mm, it is the water vapour content that matters. Finding a location where aerosol levels are minimised is a key constraint in determining the optimum site on the Antarctic Plateau for an IR observatory.

Astro Concepts is a project within Swinburne University of Technology in Melbourne developing browser-based software modules on Optical Telescopes, Nebulae and Binary Stars. The modules are designed to enhance students' understanding of basic physics concepts, which underlie introductory-level conceptual astronomy courses. When complete, the Astro Concepts modules will be available for use in university courses in introductory astronomy, introductory physics teaching, secondary teaching and online astronomy education. The strategy outlined here is to obtain a reasonable level of understanding of the necessary physics concepts by presenting them embedded in relevant and interesting astronomy contexts, and by the use of an engaging educational approach requiring active learning by the student.

We present quasi-simultaneous multi-colour optical/near-IR photometry for 157 radio selected quasars, forming an unbiassed sub-sample of the Parkes Flat-Spectrum Sample. Data are also presented for 12 optically selected QSOs, drawn from the Large Bright QSO Survey. The spectral energy distributions of the radio- and optically-selected sources are quite different. The optically selected QSOs are all very similar: they have blue spectral energy distributions curving downwards at shorter wavelengths. Roughly 90% of the radio-selected quasars have roughly power-law spectral energy distributions, with slopes ranging from Fv∝v0 to Fv∝v−2. The remaining 10% have spectral energy distributions showing sharp peaks: these are radio galaxies and highly reddened quasars. Four radio sources were not detected down to magnitude limits of H ∼ 19·6. These are probably high redshift (z > 3) galaxies or quasars. We show that the colours of our red quasars lie close to the stellar locus in the optical: they will be hard to identify in surveys such as the Sloan Digital Sky Survey. If near-IR photometry is added, however, the red power-law sources can be clearly separated from the stellar locus: IR surveys such as 2MASS should be capable of finding these sources on the basis of their excess flux in the K-band.

We present selected results from the January 1999 semester pre-course administration of the Astronomy Diagnostic Test (ADT), a research-based, multiple-choice instrument that assesses student knowledge and understanding about selected concepts in astronomy. The ADT is valid for undergraduate non-science majors taking an introductory astronomy course. This paper briefly summarises the development and validation processes, which included pre-course administration to 1557 students in 22 classes attending 17 various post-secondary institutions across the USA in the January 1999 semester. Two interesting results of the ADT's pre-course administration are (1) the average class score of the ADT is about the same (32%) regardless of type of post-secondary institution or class size and (2) there is a significant gender difference, with women scoring an average of 28% and men 38%, with the standard errors both less than 1%. The current version of the ADT (Version 2 dated 21 June 1999) and a comparative by-class database is available to astronomy instructors at the (USA) Association of Astronomy Educators' and the National Institute for Science Education's (NISE) WebPages.

Before and after every 12 hour synthesis observation, the Molonglo Observatory Synthesis Telescope (MOST) measures the flux densities of ∼5 compact extragalactic radio sources, chosen from a list of 55 calibrators. From 1984 to 1996, the MOST made some 58,000 such measurements. We have developed an algorithm to process this dataset to produce a light curve for each source spanning this thirteen-year period. We find that 18 of the 55 calibrators are variable, on time scales between one and ten years. There is the tendency for sources closer to the Galactic Plane to be more likely to vary, which suggests that the variability is a result of refractive scintillation in the Galactic interstellar medium. The sources with the flattest radio spectra show the highest levels of variability, an effect possibly resulting from differing orientations of the radio axes to the line of sight.

Infrared astronomy has made remarkable progress over the past quarter century. This paper, which is a brief summary of the 1999 Ellery Lecture, outlines the importance of the infrared, traces some of the key Australian developments in the field, and looks ahead to the challenges facing infrared astronomers in the immediate future.

In recent years, formal astronomy education has become an issue of great interest. Indeed, some boards of education now officially include astronomy in their curricula. While formal astronomy education continues to gain attention, informal astronomy education for the general public has rarely been addressed. One valuable source of informal astronomy education is the observatory ‘visitor centre’. Observatories draw thousands of visitors each year, and as such represent a golden opportunity for the astronomical community to communicate directly with the public. This paper summarises an exploratory study of the cognitive and affective impacts of a visit to the visitor centres located at Mount Stromlo and Siding Spring Observatories.

Recent history in South Africa has created unique problems in many areas. As a result of an unequal educational structure, particularly in science, there is a general lack of science literacy and awareness. Some years ago the South African Astronomical Observatory started a Science Education Initiative as a contribution to addressing this problem by using astronomy as a vehicle to stimulate an interest in science amongst teachers and students. This programme was given a boost by the South African government in 1998 and the construction of the Southern African Large Telescope will provide further stimulus to the Science Education Initiative.

We summarise the proceedings of a workshop on ‘Supernova Remnants, Pulsars and the Interstellar Medium’ which was held at the Special Research Centre for Theoretical Astrophysics at the University of Sydney on 18 and 19 March 1999.

Using the 22-m ‘Mopra’ antenna (near Coonabarabran, NSW) of the Australia Telescope National Facility (ATNF), we have observed emission from the 115-GHz J = 1−0 transition of CO towards the centre of each of the 1101 clouds listed in the Catalogue of Southern Dark Clouds (SDC) of Hartley et al. (1986). The velocity range covered was −96 to +70 km s−1, with a velocity resolution of 0· 120 km s−1. CO was detected at 1049 of the positions, with 367 spectra showing emission at more than one radial velocity. Here we present the most comprehensive general survey of the SDC catalogue, with the intensity, velocity and half-width of the CO detection and a code describing the profile shape. The presence of blue- or red-shifted wings in many observations can provide a starting point in searches for star-forming regions.

Student research projects are becoming either integral or optional components of Science curricula in several countries. They provide a valuable opportunity for high school students to experience many of the joys and frustrations that make up the intellectual challenge of Science. Astronomy is one branch of Science that lends itself to student projects. Student Research Projects (SRPs) can be individual, group or collaborative between groups in other schools or countries and may involve professional mentors. Use of the Internet and remote access telescopes allow students to undertake challenging research and make worthwhile contributions to professional programs. This paper presents case studies of student projects in optical and radio astronomy from Australian and overseas schools and details both the benefits and problems faced in conducting such projects. Student responses to involvement in projects are discussed. Potential areas for future collaboration and development are highlighted together with the need for more research as to the most effective ways to implement projects and develop student skills.

A new, direct CCD acquisition and autoguiding camera is in use on the ANU 2·3 m telescope Nasmyth foci. The camera is a model AP7 manufactured by Apogee Instruments Inc. and is controlled by the MaxIm CCD camera control and image processing software developed by Diffraction Ltd. The factors influencing our choice of this new camera are discussed, and its performance, operation, and commercial control software are described. The new camera allows stellar objects as faint as B = 21·5 to be acquired on the Double Beam Spectrograph slit in 1·4″ seeing. The camera has far superior performance to the Fairchild intensified CCD cameras that it replaces. The improved acquisition and guiding permitted by this camera has already allowed several new scientific programs to begin on the telescope, including the use of aperture plates with the Double Beam Spectrograph.

Practical astronomy is usually taught using optical telescopes or, more rarely, radio telescopes. For a similar cost, complementary studies may be made of astrophysical particles through the use of a modestly sized muon detector. Such a detector records the arrival of cosmic ray particles that have traversed the heliosphere and the rate of muon detections reflects the flux of those particles. That flux is controlled by the day to day properties of the heliosphere which is in a state of constant change as the outflowing solar wind is affected by solar activity. As a consequence, a laboratory muon detector, whose count rate depends on the state of the heliosphere, can be an interesting and useful teaching tool that is complementary to optical or radio studies of the Sun.

Donations (in cash and kind) amounting to $200,000 from companies in the south-western Sydney region have allowed the construction of a teaching, research and public access Observatory at the University of Western Sydney in Campbelltown. The Observatory will also serve as the home of the Australian Optical SETI Project (OZ OSETI for short). Two fibre-glass domes will be installed at the site. The main 4.5 m fibre-glass dome will house a 0.4 m telescope while the smaller 2.9 m dome will house a 0.3 m telescope. Both telescopes are fork-mounted Schmidt-Cassegrains working at f/10. An outside observation area will be used for tripod-mounted telescopes for public use and teaching purposes. The expected completion date for the project is July 2000.