For many years now, large plastic scintillator and geiger counter muon telescope systems have been used underground for studies of the small variations of the cosmic ray particle intensity that occur at primary energies around 1011 – 1012 eV. Although long-term deterioration in telescope counting efficiency is liable to take place it has been possible to take care of it sufficiently well to allow accurate observations to be made of the important daily variation and of transient events such as the Forbush Decrease and the solar flare increase.

It is easy to feel, on an intuitive basis, that primary cosmic rays of at least some energy range will be able to reach a satellite in earth-orbit from all directions above the local geometric horizon and from essentially no directions below the horizon. This argument suggests that directional cosmic ray detectors on board satellites may safely assume that the only particles received from earthward directions must be splash or albedo particles from the atmosphere, and that any equipment liable to possible radiation damage should be preferentially located on the earthward side of the satellite. In actual fact primary cosmic rays can have quite sharply curved trajectories in the magnetosphere, thereby enabling some particles to gain access to a satellite from a range of directions below the local geometric horizon. The present work presents recent quantitative results on this matter.

After 21 years the Parkes radio telescope has undergone a major refit. A new VAX-11/750 running VMS has replaced the aged Digital Equipment Corporation PDP-9 computer. Other new equipment includes two systems not previously available — the Mk II RING communication system (Willing and Abies 1983) and the ‘observer workstations’.

The ‘holographic’ technique for accurately measuring the surface figure of large reflector antennas, described by Bennet et al, (1976) and Scott and Ryle (1977), has many advantages over older conventional survey methods. These include high speed, low cost, and the absence of any need for additional complex mechanical or optical survey devices. In essence, the technique consists of measuring the complex far-field response of the antenna at a single frequency using a terrestrial, satellite-borne or celestial radiation source of small angular diameter. This two-dimensional pattern is then Fourier-transformed to yield the complex illumination function across the antenna aperture. Antenna surface deviations are manifested as phase fluctuations in this function. In practice, a second antenna is needed to provide a phase reference.

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.

Australian astronomers have a proud history of comet-discovery, beginning with Rumker of Parramatta Observatory in 1824 (Baracchi 1914), and culminating with the outstanding achievements of Bill Bradfield of Adelaide. In the intervening one hundred and fifty years there have been a number of other notable comet-hunters and comet-observers, the most successful being John Tebbutt (see Orchiston 1981, 1982a, 1982b), Walter Gale, David Ross, and J. F. Skjellerup. Comets discovered by these Australian astronomers, and others, are listed in Marsden’s 1982 Catalogue of Cometary Orbits.