In view of the already available reviews on the subject, the progress after 1972 is summarised. Newly identified species and molecular transitions are listed. How the studies of solar molecules can be helpful in understanding the solar atmosphere, in structuring better models and in deriving molecular parameters with some degree of confidence, is stated.

MM-(millimetre) wave astronomy offers over one hundred gigahertz of explorable spectrum within which the transitions of a large number of important molecules occur. Some of these molecules are as simple as carbon monoxide while others are as complex as trans-ethyl alcohol and methylamine; the former species are widely distributed in the Galaxy while the latter species are more localized in extent.

The five major members of the Sculptor Group of galaxies and NGC 45 have been observed with the Molongloobservatory synthesis telescope. NGC 247 and NGC 300 were not detected and upper limits to their 843 MHz flux densities are given. Radio emission from NGC 7793 is discussed with particular attention to its morphology, radial dependence compared with that of the blue light and possible coincidences between HII regions and 843 MHz peak flux densities.

Observations of the relative positions of fundamental and second harmonic bursts can be used to study refraction and scattering effects in the corona. Smerd, Wild and Sheridan have pointed out that the observed positions of type II bursts can be interpreted as favouring the backward emission of the second harmonic in a smooth corona. In this case the harmonic is seen after reflection from near the fundamental plasma level. Several other examples of type II and type III bursts have been reported which show this effect. We wish to present further evidence from a recent study of a large number of type III bursts observed with the 80 MHz heliograph and 158 MHz interferometer.

The complex flare related events taking place in the solar corona are becoming better understood as more observations are made with high spatial and temporal resolution nearly simultaneously at widely separated radio frequencies. Similarly the magneto-plasma structures related to the so-called quiet Sun, which have been extensively studied during the recent cycle (No. 20), are now better understood because of such high resolution observations.

The primary function of the 64-m telescope, situated at Tidbinbilla near Canberra, is to communicate with and to control NASA’s unmanned interplanetary space craft (Reid et al. 1973). Similar telescopes are situated at Goldstone in California and in Madrid and are part of the NASA-JPL Deep Space Network (DSN). Under the Host Country Radio Science Agreement between the U.S. and Australia the telescope is available to Australian astronomers at times outside those committed to normal tracking. A radiometer operating atλ = 13.5 mm has been built by CSIRO for use on the 64-m telescope. It was initially used for VLBI observations of water vapour masers on baselines between the U.S., Australia and USSR (Batchelor et al. 1976).

The object EX Hya is a dwarf nova with a binary period of 98.3 min (Mumford 1964, 1967). Warner (1972, 1973a) has observed two complete cycles of this star with a photoelectric time resolution of 5 sec. These observations suggested that EX Hya can be understood in terms of the model proposed by Warner and Nather (1971) in their discussion of U Gem. In this model, a white dwarf primary of a semi-detached binary system is surrounded by a disk of gas formed from matter transfered from the secondary, which is a cool dwarf star filling its Roche lobe.

That the parent masses of white dwarf (WD) stars can exceed the Chandrasekhar limit of approximately 1.2 can be seen from star clusters that have turn-off points in excess of this mass and still contain WD. Auer and Woolf argued that WD in the Hyades and Pleiades is evidence that stars with masses larger than 2.5 can become WD. Sandage and Jones have used the luminosity function to compute the number of WD expected in several clusters. Jones estimated that the brighter of the two WD sequences arises from stars of mass greater than 1-9 Schwarzschild, for example, has stressed the importance of a knowledge of the resulting mass-loss. Deutsch has discussed mass-loss from red giants and Faulkner has summarized the relationship between the planetary nebulae and the WD. Nevertheless, the role of WD formation in the enrichment of the interstellar medium and the relationship between WD and their parent stars is unclear.

The causes of various traits of the polar motion are still unknown or uncertain. For exploring these the Chandler nutation has the advantage of being readily observable and it should be independent of external torques. This nutation shows a prograde motion of the earth’s axes of rotation and of excitation about each other. For simplicity the positions of the poles of rotation P and excitation ψ (Munk & MacDonald, 1960) are given in terms of dimensionless excitation functions which apply in principle whether they come from distributions of mass, relative motions or torques. Let O be the pole of zero excitation and R be the angular distance between P and ψ.

A simple model for solar flares is described which invokes many ion-acoustic double layers in the source region. The ability of the model to explain some of the observed characteristics of solar flares is discussed, particular attention being paid to the well-observed high-energy flare examined by de Jager et al. (1987).

Primary cosmic rays passing through the solar system carry with them valuable information about solar and astrophysical phenomena in the form of intensity and spectral variations. In order that this information be efficiently extracted from observations of the directional cosmic-ray flux at the surface of the Earth, it is essential to have accurate information available to enable the relating of the observed secondary cosmic-ray directions of motion and intensity to those outside the range of the disturbing terrestrial influences.

Angular diameters of Magellanic Cloud planetary nebulae obtained using speckle interferometry on the AAT are presented. The mass of ionized gas in each nebula is derived from the angular diameter and published Hβ line fluxes; the derived masses range from 0.005M⊙ to 0.19M⊙, with a mean value of 0.08M⊙. All the planetary nebulae observed are relatively small (diameter ≲0.13pc), young (age ≲ 2500 years), bright and dense. They are therefore almost certainly only partially ionized, so that the masses derived for the ionized parts of the nebula are lower limits to the total nebula mass.

Perhaps the most direct evidence to date for shock wave acceleration of electrons in the solar corona is provided by radio observations of Type II bursts containing herringbone structure (Roberts 1959). On spectral records the herringbones appear to resemble miniature forward and reverse drift Type III bursts extending above and below the Type II backbone.

A Photometrics CCD system containing a TH7882 chip has been in use at Mt John since 1989 October for imaging photometry. Extra control software has increased observing ease and image-header information. Photometrically the system appears to be performing satisfactorily. The blue helium star LSS 99 showed no variation exceeding ~ 1% over 40 min of observation. The blue eclipsing binary HV 1761 in the Small Magellanic Cloud is found to have approximately equal components.

The MC2 and MC3 catalogues cover two strips approximately 2° wide centred on declinations +11° and +16.5°. MC2 runs from 11h 28m to 01h 23m and MC3 from 13h 31m to 04h 11m (Sutton et al. 1974). Optical identifications up to 17h 00m have been’published (Hazard and Murdoch 1977) and identifications for the remainder exist in preliminary form (Hazard, Zotov and Murdoch, in preparation). Optical spectra are being obtained chiefly at Lick Observatory (Smith et al. 1977) and this programme is now approaching completion.

Observations of the distribution of millimetre-wavelength brightness over the quiet Sun provide an important test of models of the solar chromosphere. The author and colleagues have recently carried out two investigations of the quiet-Sun brightness at 3 mm wavelength — one by means of a total eclipse observation (Labrum et al. 1978) and the other by aperture synthesis with a two-element interferometer (Archer et al. 1978). I present here a preliminary discussion of these and other measurements of millimetre-wavelength brightness distributions and of their interpretation in terms of chromospheric structure.