Preliminary mapping of the thioformaldehyde distribution in the direction of Sgr B2 followed the detection of the 211←212 transition of interstellar thioformaldehyde by Sinclair et al. (1973). Observations were made with the Parkes 64-m telescope in conjunction with a 9 cm parametric amplifier.

By 1989 a new curriculum in Japanese elementary and secondary schools had been devised and started. I will report on the contents of the new curriculum and point out some problems in teaching astronomy in Japan identified from the results of recent research in science education. Recent research shows that it is important to know how children’s ideas and misconceptions are constructed and what role the philosophy of science may play in shaping them.

Since the Molonglo cross-type radio telescope was completed in 1967 July, a considerable proportion of the observing time has been taken with calibrating the pointing of the north-south arm. In a current programme the aim is to obtain accurate positions for sources contained in the flux density catalogue recently prepared by Wyllie. This will provide a uniform set of several hundred positions and flux density calibrators covering the +20° to −90° declination range observable at the Molonglo Observatory.

The 16-inch telescope on Canopus Hill (Tasmania) has been equipped with a Coudé spectrograph.

The mass-fraction Y of helium in the interstellar medium is between 0.22 and 0.30 wherever it has been measured and it is believed to be the sum of two components: Y P from Big Bang nucleosynthesis (BBNS) at about 100 s after the Big Bang (ABB) and a temperature near 0.1 MeV, and ΔY due to processing in stars. Precise measurements of Y p, along with balances of trace elements D, 3He, 7Li also resulting from BBNS, provide important tests of BBNS theory and of parameters of cosmology and particle physics, notably the contribution ΩBO of baryons to the mean density of matter in the universe (in units of the closure density), the number Nv of light neutrino flavours (or families of quarks and leptons) and the half-life т ½ of the neutron (Shaver et al. 1983; Yang et al. 1984; Boesgaard and Steigman 1985). Figure 1 shows the predicted abundances from Standard BBNS theory (SBBN) as a function of η = μB /nλ the ratio of baryons to photons (unchanged since e ± annihilation a few seconds ABB), which is proportional (through the known temperature of the microwave background) to ΩBO h 2 0 where h0 is the Hubble constant in units of 100 km s−1 Mpc−1. SBBN theory (which assumes a homogeneous Friedmann universe and small lepton numbers), when combined with reasonable ideas on Galactic chemical evolution that predict a primordial (D + 3He)/H ratio below 10−4, imply that η ≥ 3 × 10−10 (shown by the tall vertical line in Fig. 1), which in turn implies Y P≥0.210 if Nv = 3 and т ½≥10.4 minutes. But this limit can be somewhat relaxed if т ½ is smaller (current measurements permit values down to 9.0 minutes, e.g. Last et al. 1988) and/or if the quark-hadron phase transition around 200 MeV is first-order and leads to significant density fluctuations (Kurki-Sunonio et al. 1989; Reeves 1989).

The distribution of mass in a spiral galaxy is usually inferred from its rotation curve. The curve is most conveniently measured using part of its extreme population I such as HI or HII. This has a low velocity dispersion so that the observed tangential motion is in the absence of non-circular motions (van der Kruit and Allen 1978; Bosma 1981a, b) close to the circular velocity required to balance the gravitational force. The main difficulty is that for a detailed interpretation of the rotation curve one has to make assumptions on some general properties of the mass distribution, even though it is true that one can estimate the total mass within the last measured point to an accuracy of about a factor two. That of axial symmetry is only the simplest of assumptions. On the basis of the light distribution with a usually prominent disk component one often assumes that the mass distribution is also basically highly flattened.

A Type II solar radio burst is a relatively narrow-bandwidth metre-wavelength emission which drifts outward in the solar corona at a velocity between 500 and 1500 km s-1. It was first described by Wild and McCready (1950) and since then it has been the subject of numerous investigations (see e.g. McLean 1974; Nelson and Robinson 1975).

In recent years, a number of numerical experiments have simulated various aspects of the early stages of star formation (see Tscharnuter 1980 for a discussion and review). In all but one of these experiments, however, the effects of the interstellar magnetic field have been neglected, although observations (for example, see Verschuur 1969) suggest that in some interstellar clouds, the magnetic energy is comparable to, or even greater than, the gravitational and thermal energies. It is also believed (Mouschovias 1981), that at least at the early, diffuse stages of collapse, where the ionizing radiation can penetrate deep into the cloud, the bulk of the neutral matter will feel the magnetic forces via collisional coupling with the ionized matter. Thus there exist no observational, nor theoretical reasons justifying the neglect of the interstellar magnetic field in these numerical simulations.

The Class I/Class II division of extragalactic radio sources by Fanaroff-Riley is a manifestation of important physical differences existing in radio sources.

It is proposed that the division essentially arises from the differing Mach numbers in Class I and Class II jets. The low Mach number, Class I jets are susceptible to turbulence, are decelerated by entrainment of the surrounding medium and maintain an anomalously high surface brightness as a result. The high Mach number, Class II jets are less turbulent and remain supersonic, produce high pressure shocks along their lengths and terminate via a strong shock against the IGM.

An analysis of the energy balance in both types of source reveals jet velocities of the order of 5-10,000 km s-1 for Class I jets and mildly relativistic velocities for Class II jets.

The important rôle of optical and X-ray observations in determining the gravitational field of pressure distribution in radio galaxies will be discussed with examples given of NGC1399 and IC4296.

The globular clusters 47 Tuc (NGC 104) and NGC 6723 both belong to the group of clusters which have late-type integrated spectra and which appear to be only slightly metal deficient with respect to the stars in the Hyades.

The Stellar Interferometer at Narrabri Observatory consists of two large reflectors which focus the light from a star on to two photoelectric detectors. The output currents from these detectors contain fluctuations which correspond to fluctuations in the starlight itself. The fluctuations from the two detectors are amplified in the frequency range 10-100 Mc/s and their correlation is measured by a linear multiplier. This correlation is measured as a function of the separation between the two detectors. It can be shown theoretically that the correlation at any given baseline is proportional to the square of the fringe visibility which would be observed by a classical Michelson interferometer. It is therefore possible from observations of the correlation at different baselines to find the angular diameter of a star.

Supernovae of type II (SN II) are found to exhibit a correlation (r = 0.45 ± 0.15) between M(max) and parent galaxy luminosity. This correlation might be understood by assuming that the metal-rich red supergiant progenitors of SN II in luminous galaxies have more extended photospheres than do those of the more metal-deficient evolved progenitors of SN II on low-luminosity galaxies. For h = 0.5 it is found that SN 1987A was ∼1.5 mag fainter at maximum in blue light than any other well-observed SN II. For h = 1.0 SN 1948B, SN 1973R, SN 1972Q and SN 1987A exhibit comparable MB(max). It would be important to undertake systematic searches for sub-luminous SN II in dwarf galaxies and in the metal-poor extreme outer regions of giant- and supergiant spirals.

The UK 1.2 metre Schmidt Telescope came into operation in 1973 with the primary purpose of extending to southern declinations the Sky Survey carried out with the Palomar 1.2 metre (48 inch) Schmidt Telescope. This telescope is, in most respects, an exact copy of the Palomar telescope, but several recent developments result in a much fainter limiting magnitude (by about 2 magnitudes) for the Southern Survey. The UK Schmidt Telescope has an aperture of 1.2m, and the spherical primary has a diameter of 1.83m and focal length 3.07m. The plates have the dimensions 356 x 356mm, giving a field of view of 61/2°; the plate scale is 67″ 1/mm.

In this paper we report an independent determination of the Location of the break (change in spectral index) in the spectrum of the diffuse X-ray background by applying a simple analysis technique to data already in the literature.

Characteristic frequencies of some modes of radial pulsations and their relative displacements have been determined for a sequence of composite polytropic stellar models having an inner zone of index n = 1 and an envelope n = 5. It is demonstrated that vibrational stability increases with the degree of central condensation of the individual two zone models.

The first version of this mission was approved by the European Space Agency (ESA) Council in 1973 but did not infact start its Phase B study until 1977. The early baseline design had been constrained by the requirement to make the spacecraft compatible in size and weight with the performance of a NASA Delta rocket, since this was seen as a necessary back-up to Ariane, then at an early stage of development. The mission payload then evolved with time due to the changing role dictated by the technical successes and observations made by the series of well-known X-ray satellites. The final spacecraft has emerged to have a unique capability since all the other X-ray satellites except the small Hakucho have now expired.

Astonomy in Sydney predates Sydney Observatory by some 70 years. Lt William Dawes arrived with the First Fleet and set up an observatory at a place now called Dawes Point at the foot of the present Observatory Hill. His instructions were to observe a comet predicted by the famous astronomer, Edmund Halley, to return about 1790.