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Like the strong non-thermal radio bursts from the solar corona and from the earth’s magnetosphere, the Jupiter radio bursts are characterized by their duration which may be from milliseconds to seconds, and by their complex structure on the frequency-time plane. In addition, they exhibit a variety of periodicities in their rate of occurrence, the primary one of which is associated with the rotation of Jupiter. The smaller physical scale of Jupiter compared with the Sun naturally leads to a much shorter time scale in the various radio phenomena and it is only recently that suitable equipment has become available to permit the detailed investigation of the dynamic spectra of the bursts with the necessary high time resolution of the order of 10–3 sec (Ellis 1973a,b,c). As in the case of the solar radio bursts, a number of distinct types of dynamic spectra are observed and they provide a convenient basis for classification.
We present the initial results of a statistical comparison of CO emission and H I self-absorption in the galactic plane at large distances from the Sun. Evidence for self-absorption by cold atomic hydrogen (Ts < 60 K) over angular scales of 3 ´-20´ was reported by Baker and Burton (1979). They suggested that this hydrogen was associated with the molecular clouds of the ‘molecular ring’ located between 4 and 8 kpc from the galactic center (Burton and Gordon 1978). Burton, Lizst, and Baker (1978) did find a correspondence between CO emission and H I self-absorption; however, their observations were not extensive enough to prove that the correspondence was statistically significant or to test their prediction that all instances of H I self-absorption are accompanied by CO emission and thus associated with molecular clouds.
Quasi-simultaneous optical/near-IR photometry is presented for a sample of 37 luminous optically selected QSOs drawn from the Large Bright QSO Survey. Most of the QSOs have decreased in brightness since discovery; this is expected in flux-limited samples. The continuum shape of most of the QSOs can be represented by a power law of the form F(v) ∝ v−0·3, but a few have softer (redder) continuum slopes.
The Schmidt camera is conceptually elegant and has a remarkable performance, but it suffers from several practical disadvantages. Two of these concern us here. First, there are very few craftsmen who are competent to make the aspheric correcting plate of the Schmidt camera compared with the number of those competent to make spherical surfaces of high quality.
The organization of the Anglo-Australian Telescope Project and the major features of the telescope design have been reported previously so only a brief description of the design aspects most relevant to the potential user will be given here.
The region of the solar atmosphere where the brightness temperature is less than 9 x 103 K. defines the photosphere and low chromosphere. In physical scale this covers the range from 300 km. below to 2 x 103 km. above the visible surface.
It is widely believed that stars form from collapsing interstellar clouds. However, molecular clouds typically contain of the order of 103 solar masses. Thus a mechanism is required that allows a collapsing cloud to fragment into a number of collapsing stellar sized sub-condensations. The early work was based on a virial theorem approach—defining a critical mass a cloud must exceed in order for its gravitational force to overcome the resistive thermal, rotational and magnetic forces, thus allowing the cloud to collapse. This critical mass is analogous to the Jeans mass for non-rotating, non-magnetic clouds. It is thought that a cloud containing several critical masses may collapse into several sub-condensations. Further, it is thought that the galactic magnetic field will cause the critical mass to decrease as the cloud collapses, allowing the cloud to fragment into a number of sub-condensations. The critical mass decreases as the cloud flattens down the field lines (since Mcrit ∝ B3/ϱ2 and B ∝ ϱk, K < ⅔ for non-isotropic collapse).
We present some preliminary results of an optical and radio study of the very active RS CVn binary HD 127535. Photometric measurements show the presence of a large amplitude wave which exhibits marked changes in shape and range on time scales as short as a few months. This photometric variation is almost certainly due to large cool starspots on the cooler, more luminous component. As part of a survey of southern active-chromosphere stars with the Parkes radio telescope, HD 127535 has been observed at 5, 8.4 and 22 GHz. No detection was made at 5 GHz, possibly because of confusion due to the angular proximity of the star to the galatic plane. However, it is one of the strongest sources detected in the 8.4 GHz survey, and is one of only two stars detected at 22 GHz. Photometry obtained two cycles before the 8.4 GHz observations suggest a possible correlation between the radio emission and the photometric wave, i.e. spot visibility, but more data are needed.
Charles Todd, who established the Adelaide Observatory on West Terrace in 1860, retired as Government Astronomer at the end of 1906. In 1908 the meteorological duties of the Observatory were taken over by the Commonwealth, and the Observatory lost most of its staff. Following the promotion of George Dodwell to the position of Government Astronomer in 1909, the Observatory was slowly re-established and undertook a range of astronomical and other work, which is described in detail in this paper. The Observatory was transferred to the University of Adelaide in 1940 and this is often taken as the closure of the Observatory. Dodwell finished working as Government Astronomer in 1952.
In April 1967 the British and Australian Governments agreed jointly to build and operate a 150-inch (3.8m) optical telescope on Siding Spring Mountain, 16 miles west of Coonabarabran, N.S.W., where the Australian National University has an established observatory. To direct the construction and subsequent operation of the new telescope it was decided to create a statutory authority to be known as the Anglo-Australian Telescope Board. Pending the formation of this board, the two Governments, acting through the Department of Education and Science in Canberra and the Science Research Council in London, set up a joint policy committee to initiate the project.
The Molonglo Observatory Synthesis Telescope (MOST), operating at 843 MHz, is currently surveying the southern galactic plane (245° <l<360°, −1.5° ≤b≤ +1.5°). The resulting maps provide images of the radio continuum with a synthesised beamwidth of 43′′ × 43′′ cosec δ and a noise level of about 1mJy. The survey involves 12-hour synthesis observations of over four hundred fields on a predefined set of field centres. About half the fields have been observed to date, and the survey is scheduled for completion in 1990. A noteable feature in many of the fields is the occurrence of widespread diffuse filamentary structure, in addition to the expected supernova remants and HII regions.
Adult education classes in astronomy have been conducted in Sydney for many years. The University of Sydney has been especially prominent in this field, holding classes in conjunction with the Sydney WEA prior to 1983, and independently since then. In the last 11 years, most of these courses have been conducted by postgraduate students from the Astrophysics and Astronomy departments in the University’s School of Physics. This paper describes these courses and points out some future possibilities in the teaching of astronomy to adult classes.
To present-day astronomers the name of Robert Ellery, by which our newly established lectureship is to be known, means little. A century ago it was a different story. Ellery was then one of the most respected scientists in the country, a leading astronomer who had been director of the Melbourne Observatory since it was founded in 1853, and who had taken it to a prominent position in international astronomy. Besides this he was a man of parts who spread his talents widely. He was a founder and long-term president of the Royal Society of Victoria, treasurer of the University Council, chairman of the committee of the Alfred Hospital, Trustee of the Public Library, the Art Gallery and the Museum, and he was an active member, latterly commander, of the local Torpedo and Signal Corps, a coastal defence unit manned by citizen soldiers. Late in life he became the first president of the Beekeepers’ Club. He was elected to the Royal Society and awarded a CMG: all in all, a man of character and achievement.
Solar X-ray bursts observed by a proportional counter carried on the IMP-F satellite have been analysed for correlation with optical Hα flares and radio bursts. The solar X-ray flux at energies greater than 3 keV was measured each 82 seconds and consisted of impulsive bursts superimposed on a slowly varying X-ray background. During June and July 1967 there were an average of ~10 bursts per day with intensities greater than 400 photons cm−2 s−1 (2 × 10−6 erg cm−2 s−1) which was the threshold for observation of a burst.