Sydney Observatory Research Articles

A Review of the Transit Circles used at Sydney and Melbourne Observatories from 1835 to 1970

This article collects all available information on the transit circles at the two oldest Australian observatories, Sydney and Melbourne. It is shown that, despite the distance from Europe and the main centres of astronomical research, useful and high standard work could be carried out with them. The first transit circle at Sydney Observatory came from its predecessor at Parramatta, just outside Sydney, but had serious faults. In 1877, Sydney Observatory received a Troughton and Simms transit circle of standard design. Williamstown Observatory, in Melbourne, had earlier, in 1861, obtained a similar, though slightly smaller transit circle, from the same maker. This was later used at Melbourne Observatory, where it was replaced in 1884 by a larger transit circle with a new design.

AUSTRALIAN ECLIPSE EXPEDITIONS: JAMES SHORT AND THE ECLIPSES OF 1908, 1910 AND 1911

Solar eclipse expeditions give us rare glimpses of astronomers of the past away from the routine work of their observatories, as well as the equipment that they used. In the early 1900s there were three eclipses in the vicinity of Australia and each time Australian astronomers were involved together with colleagues from New Zealand. The three eclipses were the 1908 eclipse observed at Flint Island near Tahiti, the 1910 eclipse observed at Port Davey, Tasmania, and the 1911 eclipse observed at Vavau, near Tonga. The astronomical photographer at Sydney Observatory, James Short, was one of those who took part in expeditions to all three eclipses. For the Flint Island eclipse Short joined an expedition organised by British amateur astronomer and aviation pioneer, Francis McClean, as he did for the Tasmanian eclipse two years later, although this time there was also an official Australian expedition. At the Vavau eclipse there was an even larger choice of expeditions with two official British expeditions, an official Australian expedition and a private expedition organised by a former participant of McClean's Tasmanian expedition. Short joined the last of these. Though there were some clouds at Flint Island in 1908 and at Vavau in 1911, some useful results were obtained, while the Tasmanian expeditions were, unsurprisingly, completely defeated by the weather.

POWER, POLITICS AND PERSONALITIES IN AUSTRALIAN ASTRONOMY: WILLIAM ERNEST COOKE AND THE TRIANGULATION OF THE PACIFIC BY WIRELESS TIME SIGNALS

In 1916 the New South Wales Government Astronomer, Professor Ernest Cooke, proposed the triangulation of the Pacific by wireless time signals, in order to improve mapping. The world was at war, and this scientific advancement was urgently required. The State Government gave Cooke authority to proceed, but later rescinded this decision. It also prevented Cooke from attending the first International Astronomical Union (IAU) General Assembly in Rome in 1919. Although Cooke became Chairman of the Longitude Committee of the Australian National Research Council in 1922, attended the Pan-Pacific Science Association Congress in 1923, joined the IAU's Commission 18 (Longitude by Wireless) in 1925, and continued to promote triangulation of the Pacific by wireless, the Sydney Observatory Board of Visitors, bureaucrats and politicians all continued to block him. This paper examines the interplay between Federal and State politics in international astronomy, using Cooke's triangulation of the Pacific project as a case study.

Influences of German science and scientists on Melbourne Observatory

The multidisciplinary approach of Alexander von Humboldt in scientific studies of the natural world in the first half of the nineteenth century gained early and lasting acclaim. Later, given the broad scientific interests of colonial Victoria’s first Government Astronomer Robert Ellery, one could expect to find some evidence of the Humboldtian approach in the operations of Williamstown Observatory and its successor, Melbourne Observatory. On examination, and without discounting the importance of other international scientific contributions, it appears that Melbourne Observatory was indeed substantially influenced from afar by Humboldt and other German scientists, and in person by Georg Neumayer in particular. Some of the ways in which these influences acted are obvious but others are less so. Like the other Australian state observatories, in its later years Melbourne Observatory had to concentrate its diminishing resources on positional astronomy and timekeeping. Along with Sydney Observatory, it has survived almost intact to become a heritage treasure, perpetuating appreciation of its formative influences.

DREAMTIME ASTRONOMY: DEVELOPMENT OF A NEW INDIGENOUS PROGRAM AT SYDNEY OBSERVATORY

The Australian National Curriculum promotes Indigenous culture in school education programs. To foster a broader appreciation of cultural astronomy, to utilise the unique astronomical heritage of the site, and to develop an educational program within the framework of the National Curriculum, Sydney Observatory launched <italic>Dreamtime Astronomy</italic>—a program incorporating Australian Indigenous culture, astronomy, and Sydney‟s astronomical history and heritage. This paper reviews the development and implementation of this program and discusses modifications following an evaluation that was conducted by schools.

Non-stationarity in daily and sub-daily intense rainfall – Part 1: Sydney, Australia

Abstract. This study was driven by a need to clarify how variations in climate might affect intense rainfall and the potential for flooding. Sub-daily durations are of particular interest for urban applications. Worldwide, few such observation-based studies exist, which is mainly due to limitations in data. While there are still large discrepancies between precipitation data sets from observations and models, both show that there is a tendency for moist regions to become wetter and for dry regions to become drier. However, changes in extreme conditions may show the opposite sign to those in average conditions. Where changes in observed intense precipitation have been studied, this has typically been for daily durations or longer. The purpose of this two-part study is to examine daily and sub-daily rainfall extremes for evidence of non-stationarity. Here the problem was addressed by supplementing one long record (Part 1) by a set of shorter records for a 30-yr concurrent period (Part 2). Variations in frequency and magnitude of rainfall extremes across durations from 6 min to 72 h were assessed using data from sites in the south-east of Australia. For the analyses presented in this paper, a peaks-over-threshold approach was chosen since it allows investigating changes in frequency as well as magnitude. Non-parametric approaches were used to assess changes in frequency, magnitude, and quantile estimates as well as the statistical significance of changes for one station (Sydney Observatory Hill) for the period 1921 to 2005. Deviations from the long-term average vary with season, duration, and threshold. The effects of climate variations are most readily detected for the highest thresholds. Deviations from the long-term average tend to be larger for frequencies than for magnitudes, and changes in frequency and magnitude may have opposite signs. Investigations presented in this paper show that variations in frequency and magnitude of events at daily durations are a poor indicator of changes at sub-daily durations. Studies like the one presented here should be undertaken for other regions to allow the identification of regions with significant increase/decrease in intense rainfall, whether there are common features with regards to duration and season exhibiting most significant changes (which in turn could lead to establishing a theoretical framework), and assist in validation of projections of rainfall extremes.

Egeson's (George's) transtridecadal weather cycling and sunspots

In the late 19th century, Charles Egeson, a map compiler at the Sydney Observatory, carried out some of the earliest research on climatic cycles, linking them to about 33-year cycles in solar activity, and predicted that a devastating drought would strike Australia at the turn of the 20th century. Eduard Brückner and William J. S. Lockyer, who, like Egeson, found similar cycles, with notable exceptions, are also, like the map compiler, mostly forgotten. But the transtridecadal cycles are important in human physiology, economics and other affairs and are particularly pertinent to ongoing discusions of climate change. Egeson's publication of daily weather reports preceded those officially recorded. Their publication led to clashes with his superiors and his personal life was marked by run-ins with the law and, possibly, an implied, but not proven, confinement in an insane asylum and premature death. We here track what little is known of Egeson's life and of his bucking of the conventional scientific wisdom of his time with tragic results.

‘Carte du Ciel’: Sydney Observatory's Role in the International Project to Photograph the Heavens

One of the most ambitious photographic projects the world has ever seen was announced at the 1887 International Astronomical Conference. Known as the Carte du Ciel’ or ‘Mapping the Stars’ project, its grand aim was to record on photographic plates the stars in the night sky. Worked on by eighteen observatories around the world, it was estimated that it would require 22,154 photographic plates. Although little known today, this project cemented the role of photography as a tool for astronomers and was in particular a major accomplishment for the Sydney Observatory, where it was worked on for over seventy years.

Australian rainfall trends and their relation to the southern oscillation index

AbstractRainfall is the key climate variable that governs the spatial and temporal availability of water. In this study we identified monthly rainfall trends and their relation to the southern oscillation index (SOI) at ten rainfall stations across Australia covering all state capital cities. The nonparametric Mann–Kendall (MK) test was used for identifying significant trends. The trend free pre‐whitening approach (TFPW) was used to remove the effects of serial correlation in the dataset. The trend beginning year was approximated using the cumulative summation (CUSUM) technique and the influence of the SOI was identified using graphical representations of the wavelet power spectrum (WPS). Decreasing trends of rainfall depth were observed at two stations, namely Perth airport for June and July rainfall starting in the 1970s and Sydney Observatory Hill for July rainfall starting in the 1930s. No significant trends were found in the Melbourne, Alice Springs and Townsville rainfall data. The remaining five stations showed increasing trends of monthly rainfall depth. The SOI was found to explain the increasing trends for the Adelaide (June) and Cairns (April) rainfall data and the decreasing trends for Sydney (July) rainfall. Other possible climatic factors affecting Australian rainfall are also discussed. Copyright © 2009 John Wiley &amp; Sons, Ltd.

A variability sample catalogue selected from the Sydney Observatory Galactic Survey

Context. A set of 55 × 10 3 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892–1932 along the galactic equator section l ∈ [275 ◦ , 335 ◦ ] with galactic latitude b ∈ [−7 ◦ , 7 ◦ ]. Short-term (30 min) and long-term (decades) magnitude variations in the data set are analyzed. Aims. Evidence is sought for a correlation between short-term and long-term variabilities which would identify stars in a non-quiescent phase. Methods. We use a reduced proper motion diagram to classify the stars in our sample into probable dwarfs, giants and other types. The validity of the kinematical classification is checked using objective-prism spectroscopic classification for 10 × 10 3 early-type stars. A search is made for statistical correlations between our variability indicators and physical and kinematical stellar properties. Results. We find that suspected photospheric activity for giant and dwarf stellar candidates is correlated with the time to cross the galactic thin disk. We estimate a significant apparent B-magnitude variation of ±0.25 over the 40 years of photographic observations, and candidates for monitoring for possible photospheric activity at the present time are selected employing a statistical colour-diagram which uses the total proper motion component as a distance indicator. Conclusions. Follow up studies of our tentative findings are suggested. Toward this aim the derived data for the set of 55 × 10 3 stars with variability information is archived as the variability Sample Catalogue. The data for a set of 2.4 × 10 5 stars along the section of the galactic equator l ∈ [275 ◦ , 335 ◦ ], |b |≤ 7 ◦ , and a set of of 1.7 × 10 5 stars along the section of the galactic meridian 330 ◦ ± 5 ◦ , b ∈ [−64 ◦ , −7 ◦ ] is also archived as a quick-look facility for seeking long-term magnitude changes since the century-old photographic

A climate reconstruction of Sydney Cove, New South Wales, using weather journal and documentary data, 1788-1791

This study presents the first analysis of the weather conditions experienced at Sydney Cove, New South Wales, during the earliest period of the European settlement of Australia. A climate analysis is presented for January 1788 to December 1791 using daily temperature and barometric pressure observations recorded by William Dawes in Sydney Cove and a temperature record kept by William Bradley on board the HMS Sirius anchored in Port Jackson (Sydney Harbour) in the early months of the First Fleet’s arrival in Australia. Remarkably, the records appear comparable with modern day measurements taken from Sydney Observatory Hill, displaying similar daily variability, a distinct seasonal cycle and considerable inter-annual variability. To assess the reliability of these early weather data, they were cross-verified with other data sources, including anecdotal observations recorded in First Fleet documentary records and independent palaeoclimate reconstructions. Some biases in the temperature record, likely associated with the location of the thermometer, have been identified. Although the 1788–1791 period experienced a marked La Nina to El Nino fluctuation according to palaeoclimatic data, the cool and warm intervals in Sydney over this period cannot be conclusively linked to El Nino– Southern Oscillation (ENSO) conditions. This study demonstrates that there are excellent opportunities to expand our description of pre-20th century climate variability in Australia while contributing culturally significant material to the emerging field of Australian environmental history.

150 years of Sydney Observatory

It is 150 years since Sydney Observatory was established on Observatory Hill in the Central Business District of Sydney. Ragbir Bhathal outlines its development from inception in 1858 to its closur e as a scientific institution in 1982.

A cascade approach to continuous rainfall data generation at point locations

High-resolution temporal rainfall data sequences serve as inputs for a range of applications in planning, design and management of small (especially urban) water resources systems, including continuous flow simulation and evaluation of alternate policies for environmental impact assessment. However, such data are often not available, since their measurements are costly and time-consuming. One alternative to obtain high-resolution data is to try to derive them from available low-resolution information through a disaggregation procedure. This study evaluates a random cascade approach for generation of high-resolution rainfall data at a point location. The approach is based on the concept of scaling in rainfall, or, relating the properties associated with the rainfall process at one temporal scale to a finer-resolution scale. The procedure involves two steps: (1) identification of the presence of scaling behavior in the rainfall process; and (2) generation of synthetic data possessing same/similar scaling properties of the observed rainfall data. The scaling identification is made using a statistical moment scaling function, and the log–Poisson distribution is assumed to generate the synthetic rainfall data. The effectiveness of the approach is tested on the rainfall data observed at the Sydney Observatory Hill, Sydney, Australia. Rainfall data corresponding to four different successively doubled resolutions (daily, 12, 6, and 3 h) are studied, and disaggregation of data is attempted only between these successively doubled resolutions. The results indicate the presence of multi-scaling behavior in the rainfall data. The synthetic data generated using the log–Poisson distribution are found to exhibit scaling behaviors that match very well with that for the observed data. However, the results also indicate that fitting the scaling function alone does not necessarily mean reproducing the broader attributes that characterize the data. This observation clearly points out the extreme caution needed in the application of the existing methods for identification of scaling in rainfall, especially since such methods are also prevalent in studies of the emerging satellite observations and thus in the broader spectrum of hydrologic modeling.

The Instruments from Parramatta Observatory

Sydney Observatory, Australia's oldest existing observatory, was built in 1858 on what is now called Observatory Hill. With such a long continuous history the Observatory has a good collection of astronomical instruments relating to its own history. Moreover, the collection extends further back to Parramatta Observatory, set up in 1821 by Governor Sir Thomas Brisbane. After the closure of that observatory in 1847 its instruments were retained in the colony and given to the fledgling Sydney Observatory on its establishment.Instruments from Paramatta on display at Sydney Observatory include a brass repeating circle by the eminent Munich instrument makers Reichenbach, Utzschneider and Liebherr, a Troughton transit telescope, an equatorial telescope by Banks and a 1791 celestial globe. There is also an astronomical regulator by Hardy. Brisbane acquired some of these instruments for his previous observatory in Scotland while some were obtained specifically for his Australian observatory. This paper discusses the use of these instruments at Parramatta and their subsequent fate at Sydney Observatory.

Who were bennelong and Pemulwuy? Museums in Sydney and interpretation of eora aboriginal culture

The Eora Aboriginal People are the original inhabitants of the Sydney region [in NSW, Australia]. There are an estimated 2, 000 Aboriginal rock engravings in Sydney. Some museums in Sydney now acknowledge the traditional Aboriginal owners and use Eora words to name their exhibitions. These include: Ngaramang bayumi – music & dance (Powerhouse Museum); Merana Eora Nora – first people (Australian National Maritime Museum); Yiribana (Art Gallery of New South Wales); and Cadi Eora Birrung: Under the Sydney Stars (Sydney Observatory). The Aboriginal history of Sydney, however, is only told at the Museum of Sydney with installations, videos and spoken exhibits about Eora, the indigenous peoples of Sydney. This paper reviews the Eora Aboriginal exhibits at the Museum of Sydney. It questions whether visitors to Sydney learn about Bennelong and Pemulwuy, two key Aboriginal figures in the the early European settlement around Sydney Harbour. Sydney Aboriginal Discoveries on their Dreamtime cruise of Sydney Harbour provide another interpretation of Eora history and culture. The paper suggests the Eora heritage of Sydney should be more widely interpreted in Museums, National Parks and other public venues to rightfully acknowledge this Aboriginal history.

Comets and Communication: Amateur–Professional Tension in Australian Astronomy

AbstractAustralasian amateur astronomers, Grigg and Ross, discovered four different comets between 1902 and 1907. Controversy surrounding these discoveries led to a deterioration in relations between Australia's leading amateur astronomers and Baracchi at Melbourne Observatory, and to the eventual transfer of the ‘Australian Central Bureau’ to Sydney Observatory.

Mission impossible: William Scott and the first Sydney Observatory directorship

The Reverend William Scott (1825-1917) was the founding Director of the Sydney Observatory, and succeeded in acquiring state-of-the art astronomical instruments, establishing a network of country meteorological stations, and conducting a range of astronomical observations. He also worked to promote popular interest in astronomy, and immersed himself in the scientific culture of New South Wales. This paper examines Scott's achievements in astronomy and meteorology, the reasons for his premature resignation in 1862, and the search for his successor.

Teaching Astronomy at Sydney Observatory

Sydney Observatory is a museum of astronomy and a public observatory. It is Australia's oldest existing observatory and is now a branch of the Powerhouse Museum, the largest museum in the southern hemisphere. With 65,000 visitors each year, the observatory is popular with the public. Visitors can come during the day to see exhibits and audiovisuals and in the evenings on telescope viewing sessions. They can also take part in school holiday workshops, adult education courses or a telescope-making course. In addition, many school groups come along during the school terms to extend the astronomical knowledge of their students. Other professional services provided by the observatory include an annual guidebook with up-to-date information for the sky as seen from Sydney and an astronomical information service for the public and the media.

Sydney Observatory and Astronomy Teaching in the 90s

AbstractComputers and the Internet have created a revolution in the way astronomy can be communicated to the public. At Sydney Observatory we make full use of these recent developments. In our lecture room a variety of sophisticated computer programs can show, with the help of a projection TV system, the appearance and motion of the sky at any place, date or time. The latest HST images obtained from the Internet can be shown, as can images taken through our own Meade 16 in telescope. This recently installed computer-controlled telescope, with its accurate pointing, is an ideal instrument for a light-polluted site such as ours.

Simulation of the Effect of Season of Fire on Post-Fire Seedling Emergence of Two Banksia Species Based on Long-Term Rainfall Records

Simulations were used to investigate the effect of season of fire on seedling emergence in Banksia ericifolia and B. serrata in the Sydney region, New South Wales. The simulations were based on models of soil-surface moisture in response to rainfall, seedling emergence response to soil moisture and post-fire seed release from fruits as determined by fire intensity, derived from field and laboratory studies. Fires were modelled on the first day of each calendar month for a 50-year period. Levels of post-fire seedling emergence were calculated using rainfall data from the Sydney Observatory for the corresponding period (1931-1980). Trends in seedling emergence as a function of month of fire were examined. Alternative sets of simulations were performed to assess the effect of variations in post-dispersal seed mortality, fire intensity and induced summer dormancy. In both species, mean emergence was affected by season of fire only when a 10% per month level of post-dispersal seed mortality was simulated (there was no fire-season effect at lower mortality levels). Highest predicted emergence occurred after summer fires and lowest emergence after winter fires. A reduction in rate of seed release (lower intensity fire) and induced seed dormancy in summer also had a minor effect with respect to fire-season in B. ericifolia. Reported levels of post-dispersal seed mortality in Banksia species are often high, and therefore, the simulations suggested that there will be an effect of fire season on seedling emergence. However, given the high level of year to year variation in seasonal rainfall in the Sydney region, fire-season effects are not predictable in the short term. In the longer term, the timing of fire relative to sequences of wet and dry years may be of equal importance to season of fire in its effect on populations of these species.