The amplitude scintillations of pulsars and the broadening of their profiles are different manifestations of the scattering of the signal by fine structure in the ionized interstellar gas.

Observations of pulsar radio-emission at high time resolutions are severely constrained by interstellar dispersion.

There is reasonably strong evidence to suggest that the periodic X-ray, radio and optical variable Cir X-1 is a highly eccentric orbit (e ~ 0.8), binary system comprising an OB supergiant primary and a compact object, probably a neutron star (Whelan et al. 1977; Haynes, Lerche and Murdin 1980).

The ground level event (GLE) observed on November 22, 1977, is of interest because of the spread of onset times observed by various cosmic ray neutron monitors. Previous reports (Fenton, Fenton and Humble 1978, 1979) have discussed this matter without being able to reach definite conclusions. We have now obtained data from a further seven neutron monitors, and also some from the Imp 8 spacecraft. These data combine to suggest that the event may have been more complex than we initially supposed.

The passage of the planet Venus across the face of the Sun is an astronomical spectacle which no living person is likely to have seen. The phenomenon has played an important role in the history of astronomy and in stimulating world science and geographical discovery during the 18th century. But to Australia the transit of 1769 is of truly momentous significance: during the course of an expedition to the South Seas specially organized to observe it, Lt. James Cook discovered and chartered the east coast of Australia, hoisted the English flag, and took possession in the name of King George III.