Molonglo Observatory has played an important role in pulsar astronomy from shortly after the initial discovery announcement in 1968 to the present. Its major contribution has been in the area of searches for new pulsars – for most of the 17-year period more than half of the known pulsars were Molonglo discoveries. The history of pulsar astronomy at Molonglo is reviewed and a brief account of current observation programs is given.

This document is the final Phase A Science Report of the Australian LYMAN Science Working Group, and describes in detail the scientific objectives, technical feasibility, and engineering implementation of the LYMAN mission as developed in the Australian studies.

One of the important discoveries of astronomy is that the Universe expands: distant galaxies have large recession velocities in direct proportion to their distances. Attempts to determine a global value for the constant of proportionality between the velocity and the distance (Hubble constant) are met with difficulties by the presence of peculiar, random and streaming motions in the local region. These peculiar motions are either of primordial origin or the effect of density perturbations. These affect the mean velocity of the nearby groups in the level of 50-100 km/sec (Tammann, Sandage and Yahil 1980). However, the expected peculiar gravitationally induced motion of the Local Group towards the Virgo cluster, could be large due to the high density contrast in that direction (Sciama 1967; de Vaucouleurs and Peters 1968; Sandage, Tammann and Hardy 1972; Jones 1976). This infall motion could be as high as 500 km/sec if the anisotropy of the microwave background is interpreted to have a component of our peculiar motion towards the Virgo cluster (Peebles 1971, Boughn, Cheng and Wilkinson 1981; Gorenstein and Smoot 1981).

We present an overview of the survey for radio emission from active stars that has been in progress for the last six years using the observatories at Fleurs, Molonglo, Parkes and Tidbinbilla. The role of complementary optical observations at the Anglo-Australian Observatory, Mount Burnett, Mount Stromlo and Siding Spring Observatories and Mount Tamborine are also outlined. We describe the different types of star that have been included in our survey and discuss some of the problems in making the radio observations.

There is a large body of evidence to suggest that the anomalous OH emission sources—particularly those which are classified as class I sources—are associated with protostars. It is also known, from the theories brought forward over the past four years, that maser action can be caused by quite a variety of non-equilibrium situations. It is argued here that one particular kind of non-equilibrium situation which can plausibly be expected to exist in protostars is very similar to that proposed previously in the electron-pumping model, and that, in this new context, it can mimic most of the observed features of class I sources.

We have recently discovered evidence for a population of radio-loud quasars that is reddened by dust. The dust is either along the line of sight to the quasars or is associated with the quasars. In the latter case the dust may be in molecular clouds in the quasar’s host galaxy, or in a molecular torus around the nucleus. We are planning to use 3 mm observations to search for molecular absorption lines (CO and HCO+) associated with dust at the redshift of these quasars. If any absorption systems are detected we will be able to deduce detailed information about the physical state of the molecular gas, hopefully showing which of the proposed locations of the dust is most likely.

Ground-based observations of Jupiter’s decametric radio emission (DAM) have been reviewed by Ellis (1965), Warwick (1967, 1970) and Carr and Gulkis (1969). A startling feature of DAM is the modulating effect of Io, and interpretation of the Io effect has dominated theoretical discussions of DAM until quite recently, specifically until the fly-by s of Voyagers 1 and 2. The Voyager data showed that the DAM appears as nested arcs in the frequency-Jovian longitude plane (Warwick et al. 1979, Boischot et al. 1981). The interpretation of this arc structure has been of primary theoretical interest over the past two years. The most widely adopted explanation is that the emission from each point is confined to the surface of a hollow cone (Goldstein and Thieman 1981). This idea is not new: emission on the surface of a cone was discussed by Ellis and McCulloch (1963); Dulk (1967) derived detailed parameters for the cone (half angle 79° width 1°) from the occurrence pattern of DAM; and Goldreich and Lynden-Bell (1969) presented a theoretical interpretation of it. More recently Goldstein et al. (1979) used observational data on the Jovian magnetic field in deriving properties of the required emission cone. It seems that one requires the properties of the emission cone to vary with position in the Jovian magnetosphere to account for the nested arc pattern (Goldstein and Thieman 1981; Gurnett and Goertz 1981).

This paper reports results from a graded shield X-ray telescope experiment flown from Mildura, Australia on 29 February 1968. The experimental equipment also included the actively collimated telescope previously described. Certain preliminary results from this flight have been described elsewhere.

It has been suggested that diffuse X-ray sources observed in globular clusters may arise in bow shocks formed by the interaction of intracluster gas with a tenuous halo medium. This paper presents a study both of the cluster space motions and of the energetics of any possible bow shocks which would seem to rule out this hypothesis.

Solar flares for which protons of relativistic energies reach Earth are rare events compared with the number in which non-relativistic protons are produced. For instance, Shea and Smart (1978) have listed 139 proton events for the interval 1955-69 of which 17 were GLE’s (i.e. “ground level events” detected by the world network of cosmic ray neutron monitors). We have tentatively identified a further 11 GLE’s in the interval 1970-1977, of which 3 were in 1977 in the sunspot cycle which commenced about mid-1976 (cycle 21). Thus the average rate over the past two solar cycles has been a little over one per year.

A description of the production of astronomical speckles is given in terms of elementary physical principles. Using simple probability arguments, estimâtes are made of signal-to-noise requirements and magnitude limits for détection; data réduction techniques are discussed. A speckle System used on the AAT (Anglo-Australian Télescope) with the IPCS as detector is described.

We review the magnetic locking of the white dwarf and the companion star in AM Herculis-type binaries for various white dwarf magnetic field structures, and compare the theoretical results with observations. The model in which the white dwarf has a dipole plus a quadrupole field is found to be in closest agreement with the recent observations.

The high intensity anomalous OH emission which has been detected in the neighbourhood of HII regions exhibits remarkable polarization characteristics, narrow spectral features, and unusual ratios of line strengths. All of these unusual properties are generally believed to be attributable to maser action of some form. A knowledge of the structure of the emitting regions and their brightness temperature is necessary for the development of a satisfactory theory of the emission mechanism.

Parker realized that the solar corona would expand into a supersonic wind, whose flow could be described by hydrodynamics. Subsequently a number of such steady state models have been developed which include the energy transport equation. These models assume that the heating of the gas is confined to a thin shell at the base of the corona, but neglect the effects of solar rotation and the general magnetic field, which is carried into space by the solar wind.