In designing a stellar spectrograph, it is pointless to exceed the resolving power necessary to obtain all the information from the spectrum of a star. This is limited mainly by atomic thermal motions, giving rise to the Doppler broadening of spectral lines, by turbulence and rotation of the stellar atmospheres in which the lines are formed, and by collisional broadening.

Altogether 26 new Herbig-Haro (HH) objects have been discovered by slit spectroscopy and narrow-band CCD imagery. Several of them are very remarkable in various aspects. We have also found a total of over 1000 HH candidates in L1641, L1630 and NGC 2264 on deep Schmidt plates. Fibre spectroscopy is currently underway, confirming already some 70 HH objects. Implications of this large number are briefly discussed.

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 program to observe millimetre-wave molecular transitions in a number of southern-sky molecular clouds is under way. Molecular clouds in both the Galaxy and the Magellanic Clouds are included in the sample. The aim of the program is to build a body of observational data which can be used to derive molecular abundances in southern-sky molecular clouds.

At optical wavelengths NGC 4945 is a nondescript edge-on spiral galaxy, much of which is obscured by dense dust clouds. However, at longer wavelengths a prominent nucleus is exposed which possesses both Seyfert and star-burst characteristics. Microwave observations highlight dense molecular clouds located near the nucleus. The large velocity range of these clouds lacks an adequate interpretation.

The concept of a national centre for the analysis of archival and contemporary space astronomy data has been identified as a highly desirable objective by the Australian astronomical community for a number of years. With the approaching launch of the Hubble Space Telescope (HST), the time is now appropriate to actively pursue this objective. HST will generate a data archive of unique astrophysical significance over the course of the ≥ 20 year mission. It is essential that Australian astronomers have efficient access to this resource, both to maintain our position at the forefront of astronomical research, and to complement our major ground-based facilities (particularly the AAT and the Australia Telescope). An Australian facility would provide efficient access to HST data and also to the analysis tools and expertise necessary for utilizing the data. Archival data from other NASA and ESA missions could also be supported, and in the longer term, the facility could become the science centre for the Lyman/Quasat missions.

This paper presents the case for an Australian Space Astronomy Data Centre, reviews the astronomy missions of relevance, and addresses the role, scope and implementation timescale of the facility. Preliminary estimates are given for the resources that will be required, and possible routes for funding the centre are outlined. Above all, the report is intended as a Discussion Paper to promote further consideration of the concept and of the service that could be provided to the Australian astronomical community.

A modern coudé spectrograph for observing the spectra of stars and planets with maximum efficiency is a complex and versatile instrument, which represents an investment about equal to that for a 40-inch telescope. The trend toward special telescopes for special kinds of work began in the 1930s with Schmidt telescopes for wide angle photography, and has been followed by the use of specialized telescopes for photoelectric photometry, and more recently by telescopes for polarization measurements. Two telescopes designed for exclusive use with coudé spectrographs already exist—the 48-inch at Victoria and the 60-inch at Haute Provence. More are needed, particularly in the southern hemisphere.

Cen X-3 was first discovered by Chodil et al. Since then, observations using the UHURU satellite have shown it to be an X-ray pulsar, and it must now have become one of the most searched for objects in the sky. It is both an X-ray pulsar (P~4.8 secs) and an X-ray eclipsing binary (P~2.08712 days).

A description is given of a radar facility operating in New Zealand which measures the atmospheric trajectories and hence heliocentric orbits of earth-impacting meteoroids having radiants with declinations +5° < δ < −30° down to a limiting radar meteor magnitude of +13 (corresponding to particle sizes of ~100 μm, masses ~10−6 g). The data handling capacity of the facility permits recording, orbit reduction and efficient presentation of orbital data using graphical packages to be carried out on a routine basis. The daily yield is ~1500 individual orbits with >3×105 secured to date; this is greater than the number determined in all previous meteoroid orbit surveys combined and forms a major southern hemisphere database for dynamical studies of the solar system meteoroid population.

Type I radio bursts, as distinct from the continuum component frequently associated with them in a solar storm, are short-lived (0.1-2 s), narrow-band (2-10 MHz) bursts with frequency drift rates from 0 to 20 MHz s−1. They come from coronal regions close to the corresponding plasma levels, i.e. the frequency of radiation ω is close to the local plasma frequency ωp. They occur more frequently at frequencies above ~100 MHz but at times extend to frequencies as low as 20 MHz. Their observed equivalent brightness temperatures are usually about 109 K but they can reach 1011 K or higher. Except for an average decrease in polarization towards the limb and except for initial stages of a storm, type I bursts are strongly circularly polarized (approaching 100 per cent) in the sense of the O-mode.

At the centre of the Parkes 64—m radio telescope a region of diameter 17 m has recently been resurfaced to improve its efficiency at high frequencies. The first measurements using this section have been made at 22 GHz, in observations of both continuum sources and water tfapour masers. For these observations the receiver front-end used a mixer cooled in liquid nitrogen, followed by a 5 GHz cryogenic parametric amplifier as a second stage. The option of switching against an offset horn was available and the total systemnoise temperature was ∽ 750 K.

One of the main reasons for pursuing a gravitational as opposed to a magnetic theory is that there exist galaxies which seem devoid of gas and yet show unmistakable structure. These galaxies are among those classified as SBO2/3 to SBa(r), and I shall, after Curtis, call them theta galaxies. Examples are: NGC 1512, 1291,4693, and 2859. The theta galaxies gradually merge into ringed bar galaxies, which in turn merge into ordinary spirals.

The Sydney University Stellar Interferometer (SUSI) uses siderostats (plane, alt–azimuth mounted mirrors) to reflect starlight into the instrument. The analysis of the pointing and guidance of the siderostats by traditional methods is not practical and vector algebra has been used to develop the required algorithms. Real siderostats will not be ideal and can be modelled by a set of parameters. The methods for determining the model parameters and for incorporating them into the guidance and pointing algorithms are described. Field rotation also affects the operation of SUSI, and the field rotation angle and related quantities are also determined.

The problem of synchronizing clocks at a distance has been solved both by the use of travelling clocks (e.g. caesium beam devices) and by radio transmission of time signals, for which active satellites are used to overcome inherent errors. A group of Czech workers recently developed a method of intra-continental clock comparison which makes use of the properties of domestic television signals. This has been verified under Australian conditions in experiments carried out between Mount Stromlo Observatory and the Division of Applied Physics of the National Standards Laboratory, CSIRO, Sydney, using signals from the Australian Broadcasting Commission transmitter ABWN 5A Wollongong.

The Tidbinbilla NASA Deep Space Network tracking station near Canberra employs 64-m and 34-m antennas for deep space vehicle communication. Regular use is made of the facilities for radio astronomy via a host country agreement between the United States and Australia. To support the expanding astronomical use of the station, and in particular for the Tidbinbilla two-element interferometer (Batty et al. 1977), a small computer was installed early in 1980 to control observations. The system will also be used for as much data analysis as possible to minimize off-site computing.

It appears that the relative number of β–Cephei variables among the early B stars is comparable to the fraction of the evolutionary lifetime spent in the secondary contraction and early shell-burning phases (Lesh and Aizenman 1973a) and it may therefore be of some interest to investigate possible instability mechanisms associated with hydrogen shell-burning in stars within the mass range of 10 to 15 M ⊙ (Lesh and Aizenman 1973b).

The height-integrated Pedersen and Hall conductivities are calculated for the weakly ionized region of the solar atmosphere in the vicinity of a sunspot. The values obtained are much larger than previous authors have estimated. Dynamo theories for solar flares which rely on the photospheric region having a large resistance are untenable.