Figure 3 - uploaded by Harry Wendt
Content may be subject to copyright.
![- James Dunlop (1793 – 1848) [portrait by Joseph Backler, ca. 1843, courtesy State Library of NSW].](profile/Harry-Wendt/publication/48173566/figure/fig3/AS:277197400100864@1443100418097/James-Dunlop-1793-1848-portrait-by-Joseph-Backler-ca-1843-courtesy-State.png)
Source publication
The discoveries of the radio source Centaurus A and its optical counterpart NGC 5128 were important landmarks in the history of Australian astronomy. NGC 5128 was first observed in August 1826 by James Dunlop during a survey of southern objects at the Parramatta Observatory, west of the settlement at Sydney Cove. The observatory had been founded a...
Contexts in source publication
Context 1
... Brisbane"s departure, Dunlop also left the Observatory and moved to a cottage located approximately 1 km to the east (see Figures 3 and 4). In the backyard of his house he erected a nine-inch (23 cm) diameter reflecting telescope and in April 1826 began a punishing schedule of observations. ...
Context 2
... 1952-53 the final 12-Yagi array with a primary angular resolution of 8°×12° was erected on the cliff edge and connected to a more sophisticated receiver (see Figure 23). The receiver used with this antenna incorporated an electronic Dicke switch, which improved the stability of the receiving system considerably. ...
Context 3
... chose a new independent site for these investigations at Badgerys Creek which was a CSIRO cattle research station. From February to December 1950, Mills (1952a used a three element 101 MHz interferometer with a 60-m and 270-m baseline to obtain positions of 77 discrete sources including Centaurus A. The interferometer consisted of three broadside arrays (see Figure 30) arranged along an E-W baseline. Each of the broadside antennas could be rotated in elevation on its horizontal axis allowing a transit survey of the whole sky in different declination strips. ...
Context 4
... measurements again revealed the complex nature of the brightness distribution. The undulating fit of the distribution (see Figure 32) shows that it is not a simple elliptical brightness distribution, but is likely due to the presence of the two inner lobes. Using the interferometer measurements, Mills constructed an equivalent radio- brightness distribution image of the central concentration of the radio source (see Figure 33). ...
Context 5
... undulating fit of the distribution (see Figure 32) shows that it is not a simple elliptical brightness distribution, but is likely due to the presence of the two inner lobes. Using the interferometer measurements, Mills constructed an equivalent radio- brightness distribution image of the central concentration of the radio source (see Figure 33). While noting that it was difficult to obtain an accurate distribution with the limited number of spacings and baseline orientations, Mills proposed that the central component of the source has an elliptical distribution with an orientation similar to that of the dust-band visible in the optical image. ...
Context 6
... 1955, Jack Piddington and Gil Trent used the 36-ft transit parabola at Potts Hill (see Figure 34) to conduct a 600 MHz survey of the southern sky. The 36-ft transit aerial had been constructed for a dedicated hydrogen-line survey by a team led by Frank Kerr, following the discovery of the 21-cm line in 1951. ...
Context 7
... 36-ft transit aerial had been constructed for a dedicated hydrogen-line survey by a team led by Frank Kerr, following the discovery of the 21-cm line in 1951. At 600 MHz the 36-ft aerial produced a 3.3° beamwidth and Trent (1956a, 1956b) were able to conduct a survey between declinations of 90° S and 50° N. From this survey they identified 49 discrete sources with a flux density greater than 100 Jy, including Centaurus A. Piddington and Trent noted that Centaurus A consisted of an extended source ~2° in diameter (see Figure 35), concentric with the more concentrated central source that had been discovered by Bolton"s group. At 600 MHz the total flux density of the source was determined to be 1300 Jy. ...
Context 8
... 600 MHz the total flux density of the source was determined to be 1300 Jy. Piddington and Trent also noted that the source appeared to overlap the background emission of a narrow region which joined the main galactic emission (see Figure 36). ...
Context 9
... and Little first tested a prototype of the new instrument at Potts Hill before a full scale 85.5 MHz instrument was constructed at the new Fleurs field station during 1953-54. The full scale Mills Cross produced a pencil-beam response with a beamwidth of 50 arcmin (see Figure 37). One of the early detailed observations made using the Mills Cross was of Centaurus A (Sheridan 1958). ...
Context 10
... of the early detailed observations made using the Mills Cross was of Centaurus A (Sheridan 1958). While the 50 arcmin beam was unable to fully resolve the central concentration of the source, the full extent of the extended source was clearly revealed (see Figure 38) and was much larger than the earlier estimates of ~2°. Sheridan (1958) noted that, assuming a distance to NGC 5128 of ~750 kpc, the linear extent of the radio source at 85.5 MHz would be 90 kpc by 30 kpc. ...
Context 11
... second cross-instrument, know as the Shain Cross, was constructed in 1956 at Fleurs field station operating at 19.7 MHz with a beamwidth of 1.4° (see Figure 39). Shain (1958) used this instrument to obtain isophotes of Centaurus A at 19.7 MHz which showed the radio source extended approximately 7.5° in a north-south direction and 2.5° in the east-west direction (see Figure 40). ...
Context 12
... & Wade (1959) found the total flux density of the source to be 1.3 × 10 4 Jy and that 23% of this could be attributed to the central source (see Figure 42). In a more detailed paper examining the extended component of Centaurus A, Wade (1959) used both 1400 and 85.5 MHz data to subtract the contribution of the central source from the extended source to reveal, for the first time, the double lobe nature of the extended source, which is now commonly associated with active radio galaxies (see Figure 43). ...
Similar publications
We report radio interferometric observations of the 12C16O 1.3 mm J = 2 – 1 emission line in the circumstellar envelope of the M supergiant α Ori and have detected and separated both the S1 and S2 flow components for the first time. Observations were made with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) interferometer in th...
We present an analysis of EUV and soft X-ray emission detected toward Comet
Lovejoy (C/2011 W3) during its post-perihelion traverse of the solar corona on
December 16, 2011. Observations were recorded by the Atmospheric Imaging
Assembly (AIA) aboard the Solar Dynamics Observatory and the X-Ray Telescope
(XRT) aboard Hinode. A single set of contempo...
The brightness temperature of the radio free-free emission at millimeter
range is an effective tool for characterizing the vertical structure of the
solar chromosphere. In this paper, we report on the first single-dish
observation of a sunspot at 85 and 115 GHz with sufficient spatial resolution
for resolving the sunspot umbra using the Nobeyama 45...
An M6.5-class flare was observed at N12E56 of the solar surface at 16:06 UT
on July 8, 2014. In association with this flare, solar neutron detectors
located on two high mountains, Mt. Sierra Negra and Chacaltaya and at the space
station observed enhancements in the neutral channel. The authors analysed
these data and a possible scenario of enhancem...
The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and XMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011 April 14 outburst. The X-ray spectra show prominent emission lines of C, N, and O, with broadening corresponding to an FWHM of ~2000-3000 km s–1, and line ratios consistent with high-density plasma...
Citations
... While Dover Heights and Hornsby Valley went on to make important contributions to international radio astronomy (e.g. see Orchiston and Robertson, 2017;Orchiston and Slee, 2002;2017: 502-511, 514-519;Orchiston et al., 2015;Robertson et al., 2010;2014), like Bankstown Aerodrome the Georges Heights field station also was short-lived (but see Orchiston, 2004;Orchiston and Wendt, 2017;Wendt and Orchiston, 2018). ...
... Of the four sources analysed by Bolton, Centaurus A was the only one located in the southern half of the sky. In an interesting historical twist, its optical counterpart NGC 5128 was first observed not far from Dover Heights, over 120 years earlier, by James Dunlop at the Parramatta Observatory, west of Sydney (see Robertson et al., 2010). ...
... 68 Permission to observe was approved by Radiophysics Chief Bowen (1911Bowen ( -1991: Hanbury Brown et al. [276]), but this was apparently unbeknown to the Parkes Director Bolton. 69 A historical article on Centaurus-A can be found in Robertson et al. [283], with more recent results in Davids et al. [284], and future studies of cosmic magnetism reviewed in Heald et al. [285]. ...
Radio astronomy commenced in earnest after World War II, with Australia keenly engaged through the Council for Scientific and Industrial Research. At this juncture, Australia’s Commonwealth Solar Observatory expanded its portfolio from primarily studying solar phenomena to conducting stellar and extragalactic research. Subsequently, in the 1950s and 1960s, astronomy gradually became taught and researched in Australian universities. However, most scientific publications from this era of growth and discovery have no country of affiliation in their header information, making it hard to find the Australian astronomy articles from this period. In 2014, we used the then-new Astrophysics Data System (ADS) tool Bumblebee to overcome this challenge and track down the Australian-led astronomy papers published during the quarter of a century after World War II, from 1945 until the lunar landing in 1969. This required knowledge of the research centres and facilities operating at the time, which are briefly summarised herein. Based on citation counts—an objective, universally-used measure of scientific impact—we report on the Australian astronomy articles which had the biggest impact. We have identified the top-ten most-cited papers, and thus also their area of research, from five consecutive time-intervals across that blossoming quarter-century of astronomy. Moreover, we have invested a substantial amount of time researching and providing a small tribute to each of the 62 scientists involved, including several trail-blazing women. Furthermore, we provide an extensive list of references and point out many interesting historical connections and anecdotes.
... While Dover Heights and Hornsby Valley went on to make important contributions to international radio astronomy (e.g. see Orchiston and Robertson, 2017;Orchiston and Slee, 2002;2017: 502-511, 514-519;Orchiston et al., 2015;Robertson et al., 2010;2014), like Bankstown Aerodrome the Georges Heights field station also was short-lived (but see Orchiston, 2004;Orchiston and Wendt, 2017;Wendt and Orchiston, 2018). ...
Between 1945 and 1961 the CSIRO Division of Radiophysics operated twenty-one field stations or remote sites in or near Sydney and Wollongong during the early development of radio astronomy in Australia. One of these field stations operated at Bankstown Aerodrome from 1947 to 1948. To date, the existence of this field station has mostly escaped documentation in the historical record. This short paper gives an overview of the work carried out at this field station in the context of the early development of Australian radio astronomy.
... While Dover Heights and Hornsby Valley went on to make important contributions to international radio astronomy (e.g. see Orchiston and Robertson, 2017;Orchiston and Slee, 2002;2017: 502-511, 514-519;Orchiston et al., 2015;Robertson et al., 2010;2014), like Bankstown Aerodrome the Georges Heights field station also was short-lived (but see Orchiston, 2004;Orchiston and Wendt, 2017;Wendt and Orchiston, 2018). ...
Between 1945 and 1961 the CSIRO Division of Radiophysics operated twenty-one field stations or remote sites in or near Sydney and Wollongong during the early development of radio astronomy in Australia. One of these field stations operated at Bankstown Aerodrome from 1947 to 1948. To date, the existence of this field station has mostly escaped documentation in the historical record. This short paper gives an overview of the work carried out at this field station in the context of the early development of Australian radio astronomy.
... Four months later, Bolton, Stanley and Slee (1949) completed their pioneering paper "Positions of three discrete sources of galactic radio-frequency radiation" which was published in the leading English scientific journal, Nature. They found that "… all three sources correspond within limits of experimental error to positions of certain nebulous objects …", and they were able to identify Centaurus A with NGC 5128 (see Robertson et al. 2010), Virgo A with NGC 4486 (M87), and confirm the Taurus A Crab Nebula association (see Fig. 23.15). A much more detailed account of this work, which included the first radio spectra, was subsequently published in Australia (Stanley and Slee 1950). ...
Between 1945 and 1950 New Zealand and New Zealand-based scientists hosted or initiated no fewer than five different radio astronomy projects, during the formative years of international radio astronomy. Four of these focused on solar radio emission, while the fifth was related to discrete sources (which, initially, were known as ‘radio stars’). One of the solar projects involved the independent discovery of solar radio emission; another project resulted in one of the world’s first graduate theses on solar radio astronomy; and a third solar project saw the publication of a paper in Nature, the first by a New Zealand astronomer. The sole non-solar project was mounted by two scientists from the Australian CSIR’s Division of Radiophyiscs, who successfully used observations made in New Zealand to identify optical correlates for three different ‘radio stars’, and show that they were in no way associated with stars (indicating that the term was a misnomer).
... Meanwhile, at Dover Heights the pressure was also on to search for more of these so-called 'radio stars', and this led to a survey with the 100 MHz sea interferometer, starting in November 1947. The first success came on November 6 when Taurus A ( Fig. 19.8) was found , and it was followed over the next few months by two others, Centaurus A (Robertson et al. 2010) and Virgo A. This was quite an achievement given the primitive nature of the equipment, which … was very cranky … you got interference patterns one day and wouldn't get them the next. Equipment would fail … The sea interferometer had a lot of nasty habits, like you could get interference wiped out by refraction problems and get sources rising ten minutes of time late and all this sort of crazy stuff … (Stanley 1974 The next priority was to determine accurate positions for these sources so that optical correlates could be sought. ...
... Equipment would fail … The sea interferometer had a lot of nasty habits, like you could get interference wiped out by refraction problems and get sources rising ten minutes of time late and all this sort of crazy stuff … (Stanley 1974 The next priority was to determine accurate positions for these sources so that optical correlates could be sought. This was achieved in mid-1948 when observations made from high coastal cliffs near Auckland, New Zealand (see Fig. 19.9), allowed the identification of Taurus A with the Crab Nebula, and Centaurus A and Virgo A with extragalactic nebulae (Bolton et al. 1949), showing convincingly that the term 'radio star' was a misnomer and that these objects generated almost unbelievable levels of radio energy (see Orchiston 2016, Chapter 24;Robertson et al. 2010Robertson et al. , 2014. But more than this, these identifications revealed the potency of radio astronomy to many optical astronomers for the first time, and marked the start of 'bridge-building' between these two disparate groups of scientists (c.f. ...
During the period 1946–1961 Australia was one of the world’s leading nations in radio astronomy and played a key role in its development. Much of the research was carried out at a number of different field stations and associated remote sites situated in or near Sydney which were maintained by the Commonwealth Scientific and Industrial Research Organisation’s Division of Radiophysics. The best-known of these were Dover Heights, Dapto, Fleurs, Hornsby Valley and Potts Hill. At these and other field stations a succession of innovative radio telescopes was erected, and these were used by a band of young scientists—mainly men with engineering qualifications—to address a wide range of research issues, often with outstanding success.
... Cozens and White 2001 ;Cozens et al. 2010 ). Although there also were some problems with his catalogue (Bhathal 2012 ) , with the benefi t of hindsight one of his most signifi cant discoveries was the extragalactic nebula now known as NGC 5128, which much later was correlated with the discrete radio source Centaurus A (see Robertson et al. 2010 ). ...
Once he acquired the clock-driven 8-in. Grubb refractor John Tebbutt was able to expand his existing observational programmes and introduce new ones. Thus, he could observe fainter comets for longer, measure closer double stars, make more positional observations of planets, track more minor planets, record a wider range of Jovian satellite phenomena and time more lunar occultations of stars.
In this chapter we survey the above-mentioned areas of observation, but in order to provide a realistic perspective on Tebbutt’s overall programme of observations we also review those objects and events he continued to observe that did not require the added light grasp of the 8-in. refractor or always demand a drive. Thus, this chapter also discusses his observations of variable stars, solar and lunar eclipses, transits of Mercury and lunar occultations of planets.
... Then in a paper published in Nature, Bolton et al. (1949: 101) discussed all four sources, reporting that "… three [of these] sources correspond within limits of experimental error to positions of certain nebulous objects." They confirmed the association of Taurus A with the Crab Nebula, an expanding shell of the AD 1054 supernova (see Stephenson, 2004), and linked Centaurus A with NGC 5128, a well-known nebula featuring a distinctive dark 'lane' (Robertson et al., 2010), and Virgo A with M87 (NGC 4486), an unusual nebula accompanied by a conspicuous blue jet. Most astronomers identified these last two objects as extra-galactic nebulae, so it is interesting that Bolton, et al. (1949: 102) used the presence of associated radio sources to question their true nature: ...
Initial postwar developments in non-solar radio astronomy were inspired by Hey, Phillips and Parson's (1946) report of an intense source of radio emission in Cygnus. This so-called 'radio star' was unique, and questions immediately were raised about its true nature. But it did not remain unique for long. Observing from Sydney, John Bolton, Gordon Stanley and Bruce Slee followed up the Cygnus discovery with more radio star detections, beginning what would evolve into a long-term multi-faceted research program and one of the mainstays of the CSIRO's Division of Radiophysics. But more than this, these early discoveries in England and in Sydney opened up a whole new field of investigation, extragalactic radio astronomy, which has remained a major area of investigation through to the present day. This paper focusses on the early years of this program when the observations were carried out at Dover Heights Field Station in Sydney, and the ways in which new developments in instrumentation that allowed a major expansion of the program eventually led to the closure of Dover Heights and the founding of the Fleurs Field Station.
... Four months later, completed their pioneering paper "Positions of three discrete sources of galactic radio-frequency radiation" which was published in the leading English scientific journal, Nature. They found that "… all three sources correspond within limits of experimental error to positions of certain nebulous objects …", and they were able to identify Centaurus-A with NGC 5128 (see Robertson et al. 2010), Virgo-A with NGC 4486 (M87), and confirm the Taurus-A Crab Nebula association. A much more detailed account of this work, which included the first radio spectra, was subsequently published in Australia (Stanley and Slee 1950). ...
New Zealand’s role in unravelling the true nature of ‘radio stars’ during the 1940s is recounted, and more recent studies of galactic and extra-galactic radio emission undertaken in New Zealand are summarized.
