"Dover Heights led the way from Solar observations to the Cosmos" - Gordon Stanley.
All enquiries should be directed to
Jessica Chapman (02) 9372-4196 or John Sarkissian (02) 6861-1769
"Dover Heights led the way from Solar observations to the Cosmos" - Gordon Stanley.
All enquiries should be directed to
Jessica Chapman (02) 9372-4196 or John Sarkissian (02) 6861-1769
To commemorate the international scientific importance of Rodney Reserve, the CSIRO Australia Telescope National Facility (ATNF), Australia's national radio astronomical research facility and a successor to the Division of Radiophysics, is erecting a full-size replica of one of the early radio telescopes on this site, together with an interpretative display.
On Sunday, 20 July, the Australia Telescope National Facility, in collaboration with the Waverley City Council, will be holding an opening ceremony to coincide with the General Assembly of the International Astronomical Union which will be held in Sydney in July 2003. Her Excellency, Marie Bashir, Governor of NSW, will be the guest of honour at the ceremony.
The display and replica antenna will offer visitors to Rodney Reserve an insight into the pre-eminent position that Australia occupied in international astronomy during the 1940s and 50s and reveal the innovative work that our scientists undertook during the formative years of radio astronomy.
The earliest astronomical observations at Dover Heights were carried out in 1946, using simple Yagi antennas (Figure 1) to study the Sun and the first `radio stars'. The solar observations showed that radio outbursts were connected with sunspots and solar flares, while the radio star observations revealed that these radio sources were associated with known optical objects: gaseous nebulae in our own Galaxy, and - more surprisingly - distant galaxies. This was a major breakthrough in international astronomy.
At first, simple twin-Yagis were mounted on the roof of the WWII block house, and used to study radio emission from the Sun and the first `radio stars'. Successively more elaborate aerials were then erected on the block house, culminating in the 9-Yagi array, which in 1949 was used to carry out the first detailed search of the sky for sources of radio emission.
The following year, in 1950, the Division's first parabolic `dish' antenna, with a diameter of 4.9 metres, was constructed and mounted on the roof of the block house in place of the 9-Yagi array.
In 1951 the 8-Yagi array was constructed and installed on a mounting close to the block house that formerly held a WWII radar antenna. This aerial was later upgraded to a 12-Yagi array, and this new radio telescope, one of the most powerful in the world, was used to search the sky for new radio sources. By the end of the survey, the number of known sources had jumped from a mere handful to more than 100!
After Bolton, Stanley and Slee demonstrated that the design concept worked, the `hole-in-the ground' antenna was extended to a diameter 24.4 metres and the surface was coated with concrete. This radio telescope was used to survey the sky for radio sources, and for a detailed study of a strong radio source that was detected in the constellation of Sagittarius. The radio astronomers realised that this source (called Sagittarius A) was located at the very centre of our Galaxy! These observations gained further fame for Australia and Dover Heights when in 1958 the International Astronomical Union decided to adopt the position of Sagittarius A as the coordinate centre for the system of galactic `latitude' and `longitude' that is still used today by all astronomers.
In 1954 the focus of the Division of Radiophysics shifted to the Fleurs field station, and the Dover Heights facility was closed down, bringing to an end a remarkable decade of scientific breakthroughs and achievement. More than any other field station, Dover Heights helped establish Australia's reputation as the world's leading nation in the emerging field of radio astronomy.
In order to provide a clear view of the historic antenna mounting and the replica Yagi array, a 9.6m stretch of the boundary fence immediately south of the gate will be moved some 3.5m to the east. By creating this special `viewing precinct', visitors also will be able to see the small adjacent coast flat where the blockhouse was located. The display will be installed immediately adjacent to, and on the seaward side of, the security fence, at the southern end of the viewing precinct. In this position it will be easily visible to visitors near the fence, but will not pose a security risk to them or to other users of Rodney Reserve.
In addition to the display panels and commemorative plaque, a full-size replica of the 8-Yagi array will be constructed and installed 2m to the south of the mounting that supported the original antenna (upon close examination the original mounting was found to be in far too dilapidated a condition to be used to support the replica antenna, as was originally intended).
The combination of display panels and an impressive-looking radio telescope that extends about 4.2 metres above ground level should maximize visitor interest in the scientific history of this site. The antenna will be permanently oriented towards the north-east so that visitors in the viewing precinct obtain the best possible view of it.
The convention program includes a session on `Early Developments in Australian Radio Astronomy' and a session on `Pioneering Observations in Radio Astronomy'. In consultation with the Waverley Council, an official opening ceremony at the Dover Heights site will be held on 20 July as part of the IAU historical sessions. Visitors to the IAU will be invited to attend and we anticipate over one hundred eminent astronomers will be present. Other visitors to the event will include the Heritage Branch of the Australian Institute of Engineers, staff from the NSW Government's Heritage Branch and other Council guests, the Mayor of the Waverley Council, distinguished visitors, ATNF staff, staff from the Waverley Council and local people. Her Excellency, Dr Marie Bashir, Governor of NSW, will be the guest of honour at the ceremony.
INVITATION ONLY
Date: Sunday, 20 July 2003.
Time: 12:00 pm to 3:15 pm
Place: Rodney Reserve, Dover Heights.
Programme:
The installation of display panels, a commemorative plaque and a full-size replica of one of the early radio telescopes will provide an enduring memorial to celebrate the scientific achievements at this field station between 1946 and 1954, the remarkable succession of radio telescopes that graced the site, and the talented young scientists who worked there. An opening ceremony of this new heritage precinct is planned for the July 2003 General Assembly of the International Astronomical Union, and this will make for an attractive media event.
Permission is granted to use these images. The photographs must be credited to CSIRO.
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2-Yagi array erected on the blockhouse at Dover Heights in February 1947. Operating at 100 MHz, this was first used by Payne-Scott, Yabsley and Bolton to study solar radio emission and later by Bolton, Stanley and Slee for their investigation into discrete sources (then still known as "radio stars"). This antenna was used in conjunction with a 4-Yagi array at 200 MHz, a 2-Yagi array at 60 and 100 MHz and a single Yagi at 85 MHz. At the time it was photographed the array was being used for solar observations.
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This panoramic view, looking northeast, shows the 3.9 metre equatorially-mounted antenna on the Dover Heights WWII blockhouse, the 100 MHz 12-Yagi array, and in the foreground one of the two azimuth interferometer 4-Yagi arrays (the second of these was located between the 12-Yagi antenna and the blockhouse).
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Artistic view of the 3.9 metre equatorially-mounted dish on the top of the WWII blockhouse, with star trails in the background. This dish was made in 1950 by the Dover Heights team and initially was mounted on the ex-WWII gun-laying trailer adjacent to the bloackhouse. This dish was used by Stanley and Slee to experiment with receivers at higher frequencies than had been used to that date with Yagi arrays at this site.
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View looking south, showing the 12-Yagi array on the ex-WWII radar mount at Dover Heights, adjacent to the blockhouse. This antenna started off as an 8-Yagi array in 1951, and in early 1952 was upgraded to a 12-Yagi array, using cannibalised elements of the earlier 9-Yagi array that had earlier stood on the roof of the blockhouse. This antenna had a 12 degree beam and was used to carry out the last major survey at Dover Heights Operating at 100 MHz. In all, 104 discrete sources were detected.
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View of the 12-Yagi array looking south along the coast. This antenna was used at 100 MHz to carry out a sky survey and detected 104 discrete sources. This survey marked the end of the various projects using sea interferometers at Dover Heights.
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The 12-Yagi array on the ex-WWII radar mount at Dover Heights, adjacent to the blockhouse. This antenna started off as an 8-Yagi array in 1951, and in early 1952 was upgraded to a 12-Yagi array, using cannibalised elements of the earlier 9-Yagi array that had earlier stood on the roof of the blockhouse. This view shows one of the radio astronomers adjusting the antenna, and in the background is the 3.9 metre parabolic antenna on the roof of the blockhouse.
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Artistic view of the 12-Yagi array at Dover Heights, looking east at sunrise.
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View of the 24.4m (80ft) `hole-in-the-ground' antenna during construction in early 1953. The wooden jig, made at the Radiophysics Laboratory, was used to produce a genuine parabolic shape for the concrete coating of the dish.
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View of the 2.4 metre `hole-in-the-ground' antenna constructed in 1953, and used in 1953 by McGee, Stanley and Slee to conduct a survey of the galactic plane at 400 MHz, which led to identification of Sgr A* with the galactic centre. Other discrete sources were also discovered.
In this photograph Gordon Stanley is adjusting the position of the aerial mast.
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Another view of the `hole-in-the-ground' telescope.
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Diagram demonstrating the basis of the various Dover Heights sea interferometers, which operated on the Lloyd's Mirror principle.
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Sea interferometer record of the strong radio source, Cygnus A, obtained at Dover Heights on 22 October 1948 using a 4-Yagi array operating at 200 MHz. Superimposed on the interference fringes are the intensity fluctuations for which this source was well-known.
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Iosphotes of 400 MHz emission in the region of the Galactic Centre, showing the source Sgr A*. The two obliquely-oriented "bulges" in the contours are an artifact of the antenna system. These observations were made with the "hole-in-the-ground" antenna at Dover Heights, and the position of Sgr A* was subsequently adopted by the IAU as the datum point for the international system of galactic latitude and longitude. Note how the position of Sgr A* does not coincide with the centre of the coordinate reference frame that is, 0 (or 360) longitude and 0 latitude. The coordinate frame was first determined by optical astronomers, but the Dover Heights investigations revealed the true position of the galactic centre. This new position was subsequently adopted by the IAU and the reference frame was adjusted to reflect this.
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What is a radio galaxy?
Galaxies contain billions and billions of stars just like our sun. At night we can see the galaxy that we live in stretching across the sky - we call it the Milky Way. Many galaxies contain massive black holes at their centres, sometimes weighing billions of times more than our sun. In some galaxies these black holes are sucking in the material around them, spinning it up fast and then squirting it away from the black hole at close to light speed, as a jet. These jets produce radio waves that radio telescopes like the one that was operating at Dover Heights can detect - galaxies such as these are called radio galaxies. The picture is a montage using images from various sources, and shows one of the very first radio galaxies to be identified, right here at Dover Heights, a radio galaxy called Centaurus A (the name means that it is the brightest radio source in the constellation of Centaurus, the half man and half horse creature of Greek mythology). On the left hand side is a complete image of the radio emission from the Centaurus A radio galaxy (made by the "Dish" at Parkes). The other images in the picture, moving from left to right, zoom in closer and closer to the black hole that lies at the centre of the radio galaxy. In the last images you can see the jet of material being produced from near the black hole.
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