SOUTHERN ASTRONOMERS and AUSTRALIAN ASTRONOMY
ASTRONOMY IN AUSTRALIA
Compiled by
HARLEY WOOD
SYDNEY OBSERVATORY
PRINTED AND PUBLISHED IN AUSTRALIA BY
V. C. N. BLIGHT, C.B.E., GOVERNMENT PRINTER
NEW SOUTH WALES 1973
29,63-A
INTRODUCTION
I have selected this following article because it
gives some modern perspectives on the development and achievements of
astronomy in Australia from roughly about the 1940s through to 1973.
It was during the time when Australia was starting reaching its true
zenith of theoretical and observational astronomy. This interesting
publication was produced somewhere between late 1972 and early
1973.
The original copy was handed to me at only my second
amateur astronomical meeting, and I even attended the celebratory
lecture held before the sitting of Fifteenth (XV) International
Astronomical Union (IAU) General Assembly in Sydney between 21st and
30th August 1973. This important major international scientific
conference was well publicised, and was well received in the local
amateur and professional astronomical community — deemed as a
scientific celebration within this country. Coincidentally, the IAU
was to again hold its Twenty-Fifth (XXV) General Assembly in Sydney
between 13th and 26th July 2003 — almost exactly thirty years
later.
Although this too was a great success, my own
opinion thinks this 1973 event was far more important and
influential. After the IAU event, the Australian Federal Government
significantly increased funding for new facilities and better radio
and optical telescopes. Australian astronomy did continue its ascent
in the eyes of the world, whose real contributions continue to make
its mark today in the international astronomical community.
Much of the information of this document was to
promote Australian astronomy to the IAU delegates, and on some level
is, frankly, just pure propaganda. However, this view would be a
little superficial because much support was given to the Australian
sciences during to, and prior, to this time.
Andrew James
Updated: 19th December, 2010
ASTRONOMY IN AUSTRALIA
It is fitting to prepare an account of astronomy in
Australia at the time of the General Assembly of the International
Astronomical Union in Sydney — the first assembly in the
Southern Hemisphere. The most natural way to do this is to consider
the institutions in turn and the most natural arrangement is to treat
them in order of their foundation or their engagement in
astronomy.
SYDNEY OBSERVATORY — Even at the time of the
foundation of Sydney in 1788 an astronomer, William Dawes,
established a small observatory with the duty of looking for a comet
which Halley and Maskelyne had conjectured would return in 1789. Then
in 1821, Governor Brisbane established his observatory at Parramatta.
Governor Brisbane’s observatory began
pioneering work in southern astronomy, continued after his departure
and remained until 1848.
Soon afterwards the need for astronomical facilities was again
felt and the negotiations led to the establishment of Sydney
Observatory in 1856 with W. Scott as the first astronomer. Work on
positional astronomy has been carried on since that time. In 1887,
H.C. Russell, known for pioneering work in astronomical photography,
took part in the conference in Paris which led to the decision to
compile the Astrographic Catalogue and under Dr H.W. Wood there has
until recent times been a concentration of effort towards completing
the work which was published in 53 volumes. When Melbourne
Observatory closed in 1944 the responsibility for the Melbourne
section was transferred to Sydney Observatory where it was completed,
funds for publication coming from the I.A.U. Each of these two zones
is equal to the largest undertaken by northern observatories together
covering from −51° to the South Pole.
The old epoch plates of the Astrographic Catalogue and
those taken for the Astrographic Chart are being used to
derive proper motions of variable stars and of the stars in some
areas of special interest such as star clusters. Observation of the
positions of minor planets was begun in 1953 and has continued since
then. In recent years the effort in this direction has been devoted
mainly to work on those minor planets which have been selected for
use in fundamental astronomy. Co-operation with Yale University
Observatory in the photography of large areas of the southern sky led
to the publication by Yale in recent years of the catalogues of these
areas.
The observatory is at present using a wide angle astrographic lens
made by Taylor, Taylor and Hobson to photograph the southern sky. The
centres are selected so as to provide for full overlap which will
facilitate reduction of the plate measurements by overlapping
methods. The first zone to be photographed was centred in declination
−51° and the work has proceeded outward from this. At the
time of writing the centres being photographed are at −41°
and −66° which should be completed before the time of the
Assembly when the next zones outwards should be under way. [3]
Recently, approval was given by the Government for a search to
find a site at which the work of the observatory could be carried on
under conditions better than at the present one in the midst of a
great city. The work on this project shows very clearly that an
inland site, as well as taking us away from the light and smog of the
city, will provide meteorological conditions vastly better than
available at any place on the coast.
PERTH OBSERVATORY was instituted in 1896 with the
appointment, of the first Government Astronomer, W.E. Cooke. A 15 cm
meridian transit telescope and a 33 cm standard astrographic
refractor were installed in 1900 and for the next 20 years work was
concentrated on the Perth zone of the Astrographic Catalogue,
−31° to −41°. Six volumes of meridian
observations, containing positions for about 9,000 reference stars,
were published by 1913; and between 1911 and 1920, 24 volumes of the
Astrographic Catalogue appeared, covering the six declination bands
centred at −32° to −37°. The plates for the
remaining zones were measured at the Royal Observatory, Edinburgh,
but financial restrictions prevented the publication of these results
until 1949—52, when funds were made available by the I.A.U.
From about 1920 until the 1950s, the observatory’s staff was seriously reduced. However under
the late H.S. Spigl a reconstruction programme was started. First,
the astrographic telescope was put into service again and, from 1958
to 1960, it was used for observations with a Markowitz Moon Camera.
In 1961, a start was made on rehabilitating the meridian transit
telescope, but this was cut short when the observatory buildings,
which were close to the city centre, were demolished to make way for
a large building.
The observatory was re-established in 1966 near Bickley under J.B.
Harris about 30 km east of the city of Perth, in the forest which
covers the lower Darling Range of hills. The astrographic telescope
has been installed there, but the transit instrument has been
retired. From 1967 to 1971, an expedition from the Hamburg~Bergedorf
Observatory used their own 18 cm meridian transit telescope, modified
to give automatic read-out of transits and circle readings, at
Bickley for observations in the Southern Reference Star programme. At
the conclusion of their programme, the telescope has been left at
Bickley, on loan, to enable a meridian group to carry on in the Perth
Observatory.
In April, 1971, a 60 cm cassegrain reflector, with f/75 secondary,
was installed for observations in the Lowell-NASA Planet Patrol
programme. A plate camera and f/13.5 secondary are available for star
field photography when the telescope is not engaged in planet
observations.
A 40 cm Newtonian (f/4.5) cassegrain (f/20) reflector built in the
Physics Department of the University of Western Australia and
installed at Bickley in 1969 is used for direct photography,
photo-electric photometry and spectroscopy mainly by University staff
and students.
The main effort of Perth Observatory, however, is still on
positional astronomy. The meridian group is engaged in a programme on
the stars of the FK4 Sup. Catalogue. The astrographic telescope is
used mainly for positional observations of comets and minor planets,
for investigations of orbits, and for cluster proper motions studies.
Photometric observations in clusters, to supplement the proper motion
investigations, are being started on the 60 cm Lowell telescope.
[4]
MOUNT STROMLO AND SIDING SPRING OBSERVATORIES. Mount
Stromlo Observatory is situated about 11 km west of Canberra within
the Commonwealth Territory. The observatory was founded as the
Commonwealth Solar Observatory in 1924 after tests of the quality of
the site. The first Director was W. G. Duffield. It operated as a
solar observatory until the period of directorship of R. v.d.R.
Woolley when its activities were enlarged into the field of general
astronomy and, to correspond to the wider sphere, the name was
changed to the Commonwealth Observatory which first appeared on the
annual report of 1935.
During the subsequent period under Woolley, B. J. Bok and the
present Director, 0.J. Eggen, the facilities and activities of the
observatory have been much widened. After a serious bushfire in 1952
the rebuilding programme included the establishment of a good
workshop and later an optical shop and photographic laboratory. The
telescopes at the observatory includes a 2.9 m reflector erected in
1955 and a 1.27 m reflector which was formerly the “Great Melbourne Telescope” which has
been very completely reconstructed. The observatory also has the 0.66
m refractor, which was left on Mount Stromlo after a period of use by
the Yale-Columbia Observatories. The observatory acts as a host also
to the Observatory of the University of Uppsala for whom a 0.66 m
Schmidt telescope, is maintained at Mount Stromlo. In 1957 the
observatory was transferred to the Australian National University and
is now part of the Institute of Advanced Study.
The rapid growth of the city of Canberra and the realization that
a greater proportion of clear sky would be available in other parts
of the country led to an extensive site testing programme as a result
of which. Siding Spring Mountain, near Coonabarabran, was selected as
the site for a rapidly growing complex of equipment. This site is
providing dark skies with a very good proportion of clear weather and
good seeing conditions. Regular flights in light planes are
maintained between the two centres. The telescopes already
established at Siding Spring include 1.16 m and 0.6 m reflectors.
In April, 1967, the Governments of Australia and the United
Kingdom announced an agreement to build a 3.8 m telescope and
appointed the Anglo-Australian Telescope Board to supervise its
construction. The plans were quickly completed and the construction
of the telescope and its dome are proceeding in accordance with the
timetable set out early in the project. It is expected that the
reflector will be operational in 1974. At the prime focus the
telescope will be f/3.3. There will be cassegrain ratios of f/8 and
f/15 and a ratio of f/36. The mirror and secondaries form a
Ritchey-Chrétien system with correspondingly wide field and a
correcting lens system will be available at the prime focus. A full
range of instrumentation will be associated with the telescope. The
university plans to construct a 1.5 m reflector at Siding Spring in
the near future and will also service a 1.2 m Schmidt camera being
constructed by the British Science Research Council.
The observatories are equipped with a wide range of auxiliary
equipment for their telescopes. There are photometric equipment of
various kinds and spectrographs including a coudi spectrograph on the
2.9 m reflector. A large team of mechanical, electronic and computer
engineers provide the astronomers with a strong back up in developing
and maintaining the equipment. Some two dozen astronomers are well
supported by seventy administrative and technical personnel
responsible for the large workshop complex at Mount Stromlo.
Normally about six Ph.D. scholars are resident at the observatory.
Mount Stromlo is the largest observatory in the Southern Hemisphere
and its astronomers have worked in nearly all fields of astronomy and
astrophysics. Although the emphasis changes with [5] [6 Image] change
in personnel, the activity in recent years has been very much in the
fields of stellar evolution, stellar atmospheres and stellar
structure. The work has been pursued with the whole range of
observational techniques in photometry and spectroscopy together with
the associated theoretical effort. Cosmological problems, too, have
come into prominence.
THE RADIOPHYSICS LABORATORY OF THE CSIRO under Dr E. G.
Bowen began work in radio astronomy in 1945 with observation of
activity on the sun. This led Dr J. L. Pawsey and his colleagues to
establish a sea interferometer to obtain higher angular resolution
and to examine other cosmic radio sources. Six field stations were
established and the laboratory played a crucial part in the
establishment of radio astronomy as an important branch of the
science. Dr J.P. Wild, now chief of the laboratory, made detailed
investigation of solar activity and commenced the significant metre
wave spectroscopy. J.G. Bolton with colleagues located the galactic
nucleus source in 1954, W.N. Christiansen produced the grating
interferometer to obtain high resolution pictures of the sun and F.
Kerr and colleagues made the survey of the southern Milky Way and
Magellanic Clouds in the neutral hydrogen line. In 1953 the first
cross telescope by B.Y. Mills was operating. R.X. McGee and others at
Murraybank developed a multi channel receiver and made a survey of
the sky for neutral hydrogen at a much faster rate than previously
possible. The whole of the equipment used in the field stations was
designed and constructed in the Radiophysics Laboratory. There was a
stream of publications so great, more than 1,000 since 1946, as to
defy summarization and many of the workers in the radio astronomy
team went to important posts to establish radio astronomy departments
in other institutions in Australia and overseas. The 64 m radio
telescope was commissioned at North Goobang near Parkes on October,
1961. Specifications were decided upon by the laboratory staff in
about 1956. Many of the outstanding features of this telescope have
come from H.C. Minnett, B.F. Cooper and the famous aircraft designer
Sir Barnes Wallis. Other cosmic radio astronomy field stations were
closed down and a strong group of observers was assembled under the
directorship of J.G. Bolton.
Valuable results soon followed. Polarization studies revealed
Faraday rotation effects and the galactic and extra-galactic magnetic
fields. Lunar occultations of radio sources observed with the
telescope led to the discovery of a remarkable new object-the quasar
and 21 cm observations on the Milky Way and the Clouds of Magellan in
both neutral hydrogen line and radio continuum were gathered. The
Parkes Catalogue of Radio Sources was built up and the spectra of
sources was established as higher frequencies and more sensitive
receivers became available. Bolton himself carried out his own
optical observations at telescopes in California and at Mount Stromlo
for identifications.
From 1964 interesting aspects of the nature and distribution of
the hydroxyl line were uncovered aided by a receiver offering the
choice of four frequency resolutions at a time when narrow band
observations were needed for OH emission lines and wide band for the
then new recombination lines of excited hydrogen.
Wild, continued his interest in the sun, designed the
radioheliograph as a tool for fundamental studies of the solar
atmosphere in general, and of the great explosions on the sun in
particular. The radioheliograph operatesat a frequency of 80 MHz. It
has 96 parobolic aerials spaced around a circle of diameter 3 km. The
aerials are 13.7 m across, each mounted on a tower and driven to
follow the sun. The instrument was designed and, except for some
fabrication of steel structures, was built and erected at Culgoora
near Narrabri by the staff of the laboratory. In January 1968,
the CSIRO Radiophysics Laboratory moved from the building it had
occupied since its foundation in 1941 in the grounds of Sydney
University to a new site near Epping, some 18 km from central Sydney.
Bowen, who had been so successful in establishing the instrumental
resources of his laboratory retired in 1971 and Wild was appointed
head of the Division. There has been some rearrangement including the
appointment of B.J. Robinson as head of the cosmic radio astronomy
group and of S.F. Smerd of the solar radio astronomy.
Since July 1969, the Apollo 11 moon landing, the Parkes telescope
has been a major instrument in the reception of transmission from the
Apollo missions in connection wiyh which NASA has installed
electronic equipment supplying technicians to operate it.
Recent improvements at Parkes include replacement of the
reflecting surface by perforated aluminium panels enabling
wavelengths of 1.2 cm to be used, improved feeding of the paraboloid
achieved by the use of corrugated horn feed structures, and cryogenic
receivers at 6 and 3.4 cm with impetus to line and continuum survey
work. Ambient temperature parametric amplifiers at 21, 18, 11, and 9
cm have produced new astrophysical results. The processing of data is
greatly facilitated by a comprehensive PDP-9 computer and
peripherals. A digital correlator of 1,024 channels and 2 bit
operation designed and built recently at Epping will revolutionize
line operation.
The Cosmic Radio Astronomy Group is currently engaged in the
investigation of quasars and galaxies and their identification,
pulsars, polarization, Milky Way continuum surveys at low
wave-lengths, atomic and molecular line work, supernovae remnants and
other non-thermal galactic objects, the investigation of the
Magellanic Clouds.
Since 1964 the investigation of OH gas has played a large part in
the general understanding of galactic dynamics in the galactic centre
region.
Early surveys were made of hydrogen recombination lines and the
first ever observation of a radio p-transition of hydrogen was
reported from Parkes in 1967. The work is continuing. The most
complete survey of 21 cm absorption in discrete-source spectra yet
published was issued at the beginning of 1972. The two component
structure of inter~stellar hydrogen and its physical properties were
firmly established.
Since about 1970 the number of interstellar molecular compounds,
discovered mostly in U.S. institutions, has risen to more than a
score. However, the Radiophysics Laboratory has had success in recent
months with the discoveries of thioformaldehyde and methyleneimine
and has now been credited with the discovery of six interstellar
molecular lines. In this research project the laboratory has been
assisted by chemists of Monash University. There are plans to
enter the technically difficult field of millimetre waves where a
large proportion of interstellar molecular lines are expected to be
located. [9]
The radioheliograph at Culgoora supplies each second a 80 MHz
radio picture over an area of 2° × 1.6° centred on the
sun. The pictures which display right- and left-hand circularly
polarised emission are a record of the solar storms and outbursts.
The events are classified with another instrument, a solar
radiospectrograph which operates over a very large frequency range 8
Hz to 8 GHz.
In July 1969, a typical solar flare began with the usual burst of
radio waves which suddenly broke into sharp pulses of striking
regularity at intervals of 2-7 sec. lasting for about 50 pulses. At
the same time a solar shock wave was seen to be travelling out from
the flare explosion, and shortly after, cosmic rays were observed by
detectors on a satellite. Researchers in the Division have found a
simple theory which explains the sequence of events and provides a
clue to the question as to how solar cosmic rays are generated.
Work is in progress to convert the radioheliograph into a three
frequency instrument -160, 80, and 43.25 MHz — thus supplying
simultaneous information at three different heights above the solar
surface.
THE PHYSICS DEPARTMENT OF THE UNIVERSITY OF ADELAIDE
(Professor J. H. Carver) began radio meteor studies in 1950. The work
is directed towards a study of atmospheric properties by observation
of the drift of meteor trails and the determination of meteor orbits.
The orbits of 1,670 meteors were measured during the period December,
1968 to June, 1969, with a limiting radio magnitude +8. At least 30
per cent of these belong to streams. Of particular interest is a new
group of high inclination low eccentricity streams. Deceleration
measurements indicate a low density for the majority of
meteoroids.
Interplanetary scintillation of radio sources has been observed
since 1968, largely using the CSIRO radioheliograph at Culgoora. the
Crab Nebula since June, 1969, has given a complete, two-dimensional
brightness distribution of the broadened source.
An array of three spaced receiving stations recently completed
near Adelaide, operates on the two frequencies 111.5 and 236 MHz to
investigate the detailed properties of the solar wind, using
interplanetary scintillation and will also study the angular
structure of radio sources using both scintillation and long-baseline
interferometry. [10]
The Universities of Adelaide and Tasmania have collaborated in a
series of X-ray astronomy investigations using rocket and balloon
payloads. Among the discoveries of this group was the first
established variable X-ray source CEN XR-2. Energy spectra have been
studied (mainly above ~20 kev) for a number of southern X-ray
objects.
The present cosmic ray programme on extensive air showers
generated by primary cosmic rays of energy in excess of
1014 ev and, in particular, the radio signals generated by
showers in their passage through the atmosphere is expected to yield
information about their chemical composition at these high
energies.
Rocket and satellite observations of the solar ultraviolet flux
have been made in collaboration with the Weapons Research
Establishment and cover the range 1,050-1,680 Å using a number
of broad band photometers. The reflectivity of the moon measured from
rockets in the near ultraviolet (2,400-2,900 Å) and at the
wavelength of Lyman α (1,215
Å); is substantially less than at visible wavelengths. Recent
work in the laboratory includes vacuum ultraviolet studies of gases
of atmospheric and astrophysical importance.
THE WEAPONS RESEARCH ESTABLISHMENT AT SALISBURY, South
Australia, has conducted a series of interferometric studies of radio
sources using pairs of radio telescopes of the U.S. Deep Space
Network. Observations using a trans-Pacific baseline have provided
new information about the small scale angular structure of
quasi-stellar objects. The work has involved experimenters from the
Australian Department of Supply, the Owens Valley Radio Observatory,
the Jet Propulsion Laboratories and the University of Adelaide.
THE DIVISION OF PHYSICS OF CSIRO (Chief, Dr R. G.
Giovanelli) began optical observations of the sun in the late
1950’s with three instruments. The
first of these was a 13 cm flare patrol telescope which was set up
with funds provided for the International Geophysical Year, 1957-58,
and initially was located on the roof of the N ational Standards
Laboratory in Sydney. A year or so later a small solar observatory
was established at Fleurs, some 50 km west of Sydney. The equipment
at this observatory consisted of two small but highly specialized
instruments designed to photograph the sun with good spatial
resolution in white light and in the Hα line of hydrogen. Over
a number of years, these telescopes were used for a systematic
programme of photography of the fine structure of sunspots, the solar
granulation, and the chromosphere. In spite of the small aperture of
the telescopes employed, namely 13 cm, the resolution achieved with
these instruments was about 1″ of arc on the photosphere and
1.8″ of arc on the chromosphere.
The same period saw the development in the laboratory of a tunable
birefringent filter for the Hα line having a bandwidth of only
118 Å - considerably narrower than any commercially available
even at the present time. Another important instrumental development
was the “seeing monitor” which
has since been used to study the statistical variations of the solar
seeing and, incorporated into the control systems of the solar
telescopes, to obtain improved observations. [11] Various
factors combined to bring about the transition from a small field
station near Sydney to the Culgoora Solar Observatory with the CSIRO
Division of Radiophysics. The new site has proved very suitable for
solar observations, combining long periods of sunny weather, freedom
from scattered light, and sufficient periods of good seeing to permit
a concentrated attack on those problems of solar physics requiring
observations of high spatial resolution. The major optical
instrument at the Culgoora Observatory is a 30 cm refractor designed
for high-resolution photography of the sun either in white light or
in Hα. Besides a seeing monitor, the telescope incorporates a
number of novel techniques to improve image quality developed within
the Division; these include air-suction devices to maintain thermal
stability near the telescope, and a double-side canopy in place of
the familiar dome, which allows the telescope to be operated in
thermal equilibrium with its surroundings. Except for the main 30 cm
lens (from Grubb Parsons & Co. Ltd, England), all design and
construction, including the double supporting tower and housing and
the electronic subassemblies, was the responsibility of the
Division’s own workshops or of outside
contractors in Sydney or Newcastle, New South Wales.
The 30 cm chromospheric telescope is equipped with both a
commercial 0.5 Å Halle filter and the Division’s narrow-band 1/8 Å filter mentioned
above. The latter filter has now been equipped with
computer-controlled tuning: with this arrangement the observer can
programme the telescope to take a series of exposures at a number of
chosen wavelengths in the Ha line. each sequence of exposures being
triggered off by the seeing monitor at moments of atmospheric
steadiness. Since its completion in 1967 the 30 cm telescope has been
used in a variety of investigations of both the quiet and active
chromosphere. The most recent observing programme has been concerned
with waves in the chromosphere proceeding outwards from sunspot
umbrae and penumbrae. Chromospheric observations with this telescope
have attained a spatial resolution of 0.7″ of arc; this figure
compares favourably with the theoretical value for a telescope of 30
cm aperture which is 0.55″ at the wavelength of the Hα line.
The second major instrument at Culgoora is the “cinemagnetograph“ which is mounted on a 45 m tower of a
different type. The magnetograph is fed by a 20 cm telescope and
incorporates a narrow-band filter which consists of a number of
Fabry-Perot interferometers working in tandem; the spacing and
parallelism of the interferometer plates are maintained by a unique
servo system developed in the Division. The films which form output
from this installation, after subtraction, display the magnetic field
distribution on the sun. The effective spatial resolution at the
present time is approximately 3″ of arc. -Minor
instruments at Culgoora include 13 cm. flare patrol telescope which
is operated on a daily basis to provide support to the U.S. space
programme; it is financed by the U.S. National Oceanic and
Atmospheric Administration. By virtue of its longitude, Culgoora is
able to play an important part in the worldwide network of
observatories supporting such work which is likely to increase in the
years ahead. Both the flare patrol and the larger telescopes are
expected to take part in supporting NASA’s Skylab programme planned for 1973.
For many years the Division has carried out research in the fields
of radiative transfer theory and the theory of excitation of spectral
lines of interest to solar physicists. Since Dr J. H, Piddington
joined the Division in 1967, the Division’s theoretical interests have [12] expanded
to include the following topics: magnetohydrodynamical models of the
quiet chromosphere; the theory of the 22-year solar cycle and of
large-scale motions on the sun; the origin and form of the galactic
magnetic field and the origin of cosmic rays; electromagnetic effects
of Jupiter’s satellite Io; density-wave
and magnetic theories of the spiral arms of the galaxies and
electrodynamical models of radio-galaxies and quasars; and cosmical
electrodynamics generally.
In recent years Fellows from Thailand, Japan, France and the
United States have worked as Fellows alongside members of the
Division. Although so far the fellowship programme has been a modest
one, it is hoped to expand this aspect of the Division’s international activities when more
powerful and versatile observational equipment has been added to the
existing instruments.
THE DEPARTMENT OF PHYSICS IN THE UNIVERSITY OF TASMANIA
(Professor G. R. A. Ellis) is engaged in a range of activities in
astronomy. Surveys have been made of the sky in the frequency range
2-50 MHz, wavelengths longer than usually used by other radio
astronomers. Recent work has included studies of radio bursts from
Jupiter and in particular of the dynamic spectra.
X-ray investigations have been made from sounding rockets.
Experimental payloads have been developed which are launched when
opportunity arises from rockets provided by the U.K. (Skylark) or by
NASA (Aerobee and Scout).
An active programme of cosmic ray observations is being carried on
and the astronomical implications followed up.
Some investigations have been carried out on pulsars and
interstellar medium including pulse characteristics and dispersion.
The University is installing a 1 m optical telescope with
instrumentation which will give it flexibility for a variety of
astronomical work. This will include the physical and chemical
characteristics of stars and planets.
THE SCHOOL OF PHYSICS OF THE UNIVERSITY OF SYDNEY has two
departments as members of the Cornell-Sydney University Astronomy
Centre.
The Chatterton Astronomy Department (Professor R. Hanbury Brown)
was established in 1959. The major work of the Department has been
the development, construction and operation of the Stellar Intensity
Interferometer located at Narrabri Observatory about 500 km northwest
of Sydney. The building of the instrument was a joint project of the
Universities of Sydney and Manchester (U.K.) and later the Office of
Scientific Research of the U.S. Air Force.
The first instruments were made on the bright star Vega in July
1963. Since then the Stellar Interferometer has worked almost
continuously. The main observing programme started May 1965, after
establishing a completely satisfactory instrument and procedure and
ended in February 1972. Before the work began the angular diameters
of only six stars were known, all six being giants or supergiants not
representative of the main sequence; moreover, the precision of these
six measurements, made with Michelson’s
interferometer in about 1930, is not known. As a result of the work
at Narrabri, 32 single stars have been measured, many of them main
sequence stars, and the precision and repeatability of these results
is well understood.
The interferometer has also been used to develop the technique of
intensity interferometry and to explore what could be done with a
larger instrument. This work includes the measurement of the size of
the emission region surrounding a Wolf Rayet star, the measurement of
the distortion of a rapidly spinning star, and observations of the
binary star Spica. The work on Spica is of considerable potential
value because it shows how, by the use of an interferometer, all the
important parameters of a binary star, including the distance, can be
found. Other work includes experiments on the effects on an intensity
interferometer of atmospheric scintillation and the pulses of light
from the night sky due to cosmic rays entering the earth#8217;s
atmosphere. Lastly the actual technique of intensity interferometry,
in particular the electronic correlator, has been established beyond
question.
The work of the interferometer on stars finished satisfactorily in
February 1972, and no further work on stars is planned. It was
designed to measure stars brighter than magnitude +2.5 and in the
range of spectral types and luminosity classes between type 0 and F.
The exposure times for stars fainter than +2.5 exceed 100 hours per
star; so to add significantly to the work we must increase the
sensitivity of the equipment by a substantial amount. New and
exciting possibilities require a very much larger instrument some 100
times more sensitive than the present instrument at Narrabri. A
detailed proposal was prepared by the Chatterton Astronomy Department
and forwarded to the Department of Education and Science in March,
1971. This proposed novel instrument, based on the work at Narrabri,
would be capable of measuring stars to magnitude +7.5 and of making a
most valuable and original contribution to stellar astronomy. The
cost was loosely estimated at about $3 million.
At present the Interferometer is being used, in collaboration with
the Smithsonian Astrophysical Observatory in Boston, to look for high
energy gamma rays from objects outside the earth. For some years
there have been attempts, so far with no certain success, to detect
gamma rays by observing the flashes of Cerenkov light made by the
rays when they enter the earth’s
atmosphere. Gamma ray astronomy has so far been confined to a few low
energy observations from balloons or rockets. Some years ago Cerenkov
light pulses were observed using the two reflectors of the
interferometer looking simultaneously at the same part of the
earth’s atmosphere where the pulses
were generated. This original work was developed by the Smithsonian
Institution and now it may well be that the installation at Narrabri
is the most sensitive gamma ray telescope in existence. The results
of the first programme at Narrabri on gamma rays look promising and
possibly the reflectors of the Stellar Interferometer have obtained
the first really positive results in a new branch of astronomy, the
observation of celestial objects by high-energy gamma rays. The
Chatterton Astronomy Department intends to continue this work in
collaboration with the Smithsonian Astrophysical Observatory.
A programme of radio astronomy began in 1960 when Professor B. Y.
Mills joined the School of Physics with the aim of building a large
cross-type radio telescope which was funded in part by the Science
Foundation for Physics within the University, but principally by the
U.S. National Science Foundation. After design studies, construction
began in [15] 1.962 at a site located near Canberra, now the Molonglo
Radio Observatory. Observing commenced when the first arm of the
cross was completed in 1965, and the whole instrument was put into
operation in 1967.
The instrument has two arms each 1.6 km long running east-west and
north-south which intersect at their centres. Their width is
approximately 12 m, giving a total collecting area of 2 ×
104 m2. The east-west arm which is split in the
middle to allow the continuous north-south ar a set of pencil beam
responses is obtained which produces an image of the small area of
sky on the meridian. In addition to this basic system an output from
the east-west arm is available at 111.3 MHz and a current design
study aims at raising the main operating frequency to near 1,420 MHz
within the next few years.
The radio telescope is probably best known for the discovery of
many new pulsars, for which the east-west arm is ideally suited. This
work has been extended to more accurate timing and positioning of
pulsars. The main programmes, however, are concerned with sky
surveys, accurate position measurements and the mapping of extended
sources and a omplete survey of the southern sky is being made. More
than half the available area has been surveyed and the first
catalogue of a small area (~0.2 sr) containing 1,500 sources has been
prepared. The positional accuracy is typically 10″-15″
arc. Positions with accuracy about 2″ are being achieved for an
increasing number of southern sources and optical identifications
with these positions are being sought in collaboration with optical
observatories and by the use of the Palomar Sky Atlas.
Results of surveys of the Magellanic Clouds and a 6° wide
strip along the Galactic plane are being analysed. Studies of
individual Hll regions in the Magellanic Clouds have yielded electron
densities and masses, while collaboration with Mt Stromlo Observatory
has led to the identification of many non-thermal sources with
supernova remnants. Analysis of the Galactic survey has provided
significant new information about spiral structure and many new
Galactic sources which need further investigation.
A recent programme of accurate flux density measurements at 408
MHz to provide suitable calibrating sequences in the southern sky has
revealed that many sources are variable at this frequency, an
unexpected result with interesting astrophysical consequences.
In a long term programme of planetary observation when
circumstances have been favourable it has been possible to measure
the 408 MHz emission of Venus, Mars, Jupiter, and Saturn.
THE ELECTRICAL ENGINEERING SCHOOL OF THE UNIVERSITY OF
SYDNEY under Professor W. N. Christiansen operates the Fleurs
Radio Observatory, 50 km west This observatory was run by the CSIRO
from 1954-1962 and from 1963 onward by the University of Sydney. In
the earlier period it was the home of several famous radio telescopes
known as the Mills Cross (λ = 3.5
m), the Criss-cross (λ = 0.21 m).
Parts of the first and third of these telescopes remain as museum
pieces, but the second has been rebuilt and now forms part of a new
and powerful earth rotational synthesis radio telescope as well as
being used as an improved version of the grating cross-in its
original form. [16][17 Image]
The new earth-rotational synthesis telescope is a compound
interferometer consisting of thirty-two 6 m diameter paraboloids and
of two 14 m diameter arranged in a line about 1 km long in an
east-west direction. The paraboloids are all fixed in position but
can rotate on equatorial axes to follow a source in the sky for many
hours. A multichannel radio receiver connected separately to each
antenna indicates at any time, 64 sine and 64 cosine Fourier
components of the brightness distribution across the radio source
under observation. These values are recorded. After 8 hours of
observation a sufficient range of scanning angles across the source
has been investigated to allow a map of the source to be produced by
a computer. A second north-south array, similar to the east-west one,
provides a further range of scanning angles and allows sky mapping to
be done even at the celestial equator, a thing not possible with
other earth rotational synthesis instruments.
The maps produced have a field of 2 square degrees and a
resolution of 40 arc seconds at a wavelength of 21 cm. Plans are in
hand for a two-fold improvement in this resolution. In addition to
being used as a rotational synthesis telescope, the antennas can be
connected as a cross to make rapid (1/10 sec.) maps of the sun at a
resolution of 3 arc minutes. Since being brought into
operation in the middle of 1972 the synthesis telescope has been used
for mapping details of complex sources, mainly in the Galaxy and in
the Magellanic Clouds. Polarization measurements are in progress.
A second radio telescope at Fleurs operates at λ = 10 m and consists of an east-west
array, one kilometre long and a pair of movable antennas which are
used to synthesize a north-south arm. A survey of the sky between
declinations −4° and −64° has been
completed.
During the last few years work has been done on absolute
measurements of sky temperatures by means of horns and scaled
arrays.
THE DEPARTMENT OF APPLIED MATHEMATICS ON THE UNIVERSITY OF
SYDNEY under Professor K.E. Bullen for some years worked on the
internal constitution of the planets as an extension of studies of
the interior of the earth derived mainly from seismology. Now
under Professor P. R. Wilson the department has an astrophysics group
which initially undertook a theoretical investigation of solutions of
the equation of radiative transfer appropriate to inhomogeneous
atmospheres, and methods have been developed which are suitable for
the analysis of continuum and for line radiation. The most recent
development has been the use of the Foutrier technique in the study
of inhomogeneous atmospheres in the presence of non-uniform velocity
fields. Problems of line formation in magnetic fields are also under
investigation.
These methods have been applied to the investigation of a wide
variety of solar phenomena. The continuum methods have been applied
to sunspots, faculae and the photospheric granulation, while
non-L.T.E. spectral line analyses have been used to investigate
chromospheric structures.
The group has maintained close relations with the Sacramento Peak
and Kitt Peak
Observatories through the Sydney-Boulder Astrophysics Association
of which it is a founding member. Several programmes of observations
of granulation, sunspots, and structures in the chromospheric lines
have been carried out at these observatories and the data have been
used in theoretical analyses of these structures. [18]
Currently, attention is being given to sunspot models and the
cooling of sunspots, models of the convection zone, study of
chromospheric shock waves through the interpretation of Ca II K line
data and further theoretical studies of the radiative transfer
equation.
THE PHYSICS DEPARTMENT OF THE UNIVERSITY OF QUEENSLAND
began research in astrophysics in August 1958. Professor D.
Mugglestone developed a method for computing the equivalent widths of
weak lines. This was extended by one of his students to include
strong lines as well. These techniques were applied to the
determination of the solar abundance of several light elements. It
was found that for certain spectral lines of sodium and other
elements the Stark effect can be the dominant line broadening
mechanism. The importance of saturation effects was emphasized. All
the calculations at that time were based on the assumption of local
thermodynamic equilibrium.
Non-L.T.E. effects in the formation of the strong lines of sodium
and calcium were investigated. It was found that the deep cores of
these lines are a result of departures from L.T.E. In non-L.T.E.
calculations it is usually assumed that scattered line radiation is
completely redistributed both in frequency and direction. This
assumption was investigated and led to published results on the
fundamental problem of redistribution.
During a brief stay Dr G. D. Finn initiated his work on the
stochastic theory of radiative transfer. A detailed investigation of
the formation of helium lines in 33 main sequence B-type stars
uncovered additional evidence of the importance of non-L.T.E.
effects. It was found that the triplet lines of helium are sensitive
to the U.V. radiation field in these stars. In order to obtain good
agreement between theory and observation for the triplet lines it is
necessary to include the effects of line blanketing in the
ultra-violet. Work carried out on the theory of spectral line
broadening has led to a more satisfactory method of dealing with line
broadening by collisions with hydrogen and helium; a line broadening
mechanism which is very important in the cooler stars.
During 1971 and 1972 the astrophysics group has been host to Dr A.
G. Hearn who has been working on radiation pressure driven sound
waves in stellar atmospheres, which may provide a possible heating
mechanism for chromospheres in hot stars. A systematic method of
inverting individual line profiles to obtain information about the
physical conditions in the region of the atmosphere in which the line
is formed was developed with a student. The method is now being
applied to the analysis of high resolution wiggly line spectra of the
sodium D-lines and may yield further information on velocity,
temperature and density fluctuations in the photosphere.
At present, work is proceeding on the semiclassical theory of
radiation and on the redistribution of line radiation, especially in
the difficult regime where the collisional width and the natural
width of the lines are comparable.
Plans for acquisition of further high resolution wiggly line
spectra are under way. The analysis of these spectra to deduce
information about solar velocity fields and problems in atomic and
molecular physics of astrophysical interest are likely to occupy the
group for some time. [19]
THE DEPARTMENT OF MATHEMATICS AT MONASH UNIVERSITY has
worked in theoretical astronomy. Professor K. C. Westfold with
colleagues has carried out investigations on the circular
polarization of synchroton radiation which have been applied to
models of the atmosphere of the planet Jupiter. This has led to an
investigation of the effects on the frequency spectrum of a truncated
energy distribution of the ultra-relativistic electrons contributing
to the radiation. The contributions from electrons having small pitch
angles are also being studied.
Work in relativistic astrophysics and cosmology carried out by
staff members and students in 1972 was concerned with gravitational
radiation from black holes and from the collapse of rotating
cylindrical systems, with multifluid, anisotropic and scalar-tensor
cosmologies and with the examination and classification of exact
solutions of Einstein’s field
equations. Professor R. Van der Borght and colleagues are
investigating the effects of magnetic fields and rotation on
finite-amplitude convection, in view of its application to
astrophysical problems. Numerical, asymptotic and perturbation
methods have been used extensively. A start has been made with the
study of compressible and time-dependent systems. Viscoelastic
effects and problems in overstability are being investigated.
A theory of supersonic convective turbulence is being developed by
Dr A. J. R. Prentice and collaborators to account for the formation
of T-Tauri outbursts and the origin of the solar system. It is argued
that there may be sufficient energy available during the
gravitational collapse of a young proto-star to make the convective
motions strongly supersonic. Supersonic turbulent pressure causes the
star to appear much more centrally condensed and lowers the central
temperature. The protostar comes to quasi-hydrostatic equilibrium
near Neptune’s orbit and subsequently
disposes of its excess angular momentum through the formation of a
discrete system of gaseous Laplacian rings. The orbital radii of
these rings follow a Titius-Bode law and their masses are each of
order 1,000 M⊙ of solar material.
Dr J. J. Monaghan is studying uniformly rotating upper
main-sequence stars with internal magnetic fields in an to understand
the peculiar A stars. Attention has been directed to stars in
equilibrium without circulation. Both axisymmetric stars with
multipole fields and non-axis symmetric stars with dipole-like fields
are being investigated. The precession and oscillation of the
non-axisymmetric model and the effect of vorticity expulsion in
rotating stars with no magnetic field are being studied.
Work is being done on the statistical mechanics of fluids by means
of a Monte Carlo technique devised so that a range of densities can
be treated simultaneously and on transition radiation produced by
fast electron-ion encounters.
In 1971 the Department of Chemistry under Professor R. D. Brown
turned to the measurement of the spectral lines of cyclic molecules
that might occur in interstellar space. This led, in collaboration
with the CSIRO Radiophysics Laboratory using the Parkes radio
telescope, to the detection of the molecules of thioformaldehyde and
formaldimine. Monash has set up a 40 cm reflecting telescope and the
Department of Physics has plans for a programme of photometric and
spectroscopic studies of stellar atmospheres, in collaboration with
the University of Tasmania, and with the Department of Mechanical
Engineering for a study of lunar occultations. [20]
THE DEPARTMENT OF PHYSICS OF THE UNIVERSITY OF NEWCASTLE
under Professor C. D. Ellyett has for a long time been engaged on
work on meteors.
At present this is dene by radar and new equipment has been built
for the purpose. This contains highly sophisticated signal processing
instrumentation which has been developed in the Department, so that
it can now be operated with quite low transmitter power and yet
obtain higher meteor rates than were obtained in the radar meteor
work over the past two decades. Meteors are being observed as “meteoric Es” on a conventional
ionosonde to which it is hoped to add signal processing, and by
operating in this way, together with 40.68 MHz, to study the duration
and time process of meteor trails in the upper atmosphere.
THE DEPARTMENT OF SUPPLY OF THE COMMONWEALTH GOVERNMENT is
the chief agent for Australian participation in the space programme.
Australia’s geographic position away
from North America and Europe gives an advantage as a location for
stations to maintain contact with space vehicles when they would
otherwise be out of sight or radio contact. Tracking observations in
Australia began during the geophysical year 1957-8 when the mini
track facility was installed at Woomera. This was followed by the
Baker-Nunn optical tracking camera.
In 1960 an agreement was reached between the Australian and the
United States governments for the establishment of space tracking
stations in Australia. These have been financed chiefly by NASA.
There are now five stations. Mostly these have 26 m diameter
antennas. A 64 m antenna is under construction at Tidbinbilla near
Canberra. This is similar to the one at Goldstone and to one under
construction in Spain. These three will support future space missions
which require greater sensitivity or transmitting power. It is
anticipated that the 64 m telescope will be available for purely
astronomical projects.
Australia also participates in the ELDO programme by providing and
operating ground facilities and range instrumental launchings have
been made for purposes of vehicle development and the fourth was
successful in placing a satellite in orbit. The Skylark high altitude
test vehicle can be launched to heights of about 100 miles and has
been used for upper atmosphere research as well as astronomical
projects. The payloads have been of United Kingdom and Australian
origin and include experiments on X-ray astronomy. Currently some
thirteen vehicles per year are being launched.
The Department of Supply started balloon flying in a regular way
with the establishment of the balloon launching station in Mildura in
1960. At present about ten flights per year are made of which some
are being devoted to an infrared mapping survey.Several flights have
been made for X-ray astronomy in conjunction with the University of
Adelaide and the University of Tasmania. [21]
An encouraging feature of the substantial growth of astronomy in
Australia in the past 25 years has been its development in the
universities. In 1950 there was no professor or lecturer in astronomy
in an Australian university and the basic need for a vital school of
astronomy was remarked. Now almost every university is active in
astronomy or astrophysics.
The first suggestion that Australia should offer an invitation to
the International Astronomical Union to hold an assembly in Australia
came from Professor Otto Struve when he was present at a meeting of
the Australian National Committee for Astronomy. He was then
president of the union. Invitations were issued on several occasions
until a later president, Dr P. Swings, indicated in 1966 that the
executive would recommend acceptance of the Australian invitation for
1973 to the next executive which, in 1969, approved our outline
programme. Now we look forward with keen pleasure to the visit by so
many of our colleagues and friends and we hope that they will find
their Assembly in Australia pleasant and scientifically profitable.
We fully expect that contact with the whole range of astronomical
activity will prove a great stimulus to astronomy in our country.
[22]
2963 10.72 V. C. N. BLIGHT, GOVERNMENT PRINTER
Last Update : 9th October 2012
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(2010)
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