The University of Sydney is also a member of Astronomy Australia Limited (AAL), whose core business is to manage programs that provide astronomers with access to national optical/infrared and radio astronomy infrastructure.
SAIL is currently composed of about 9 laboratories that focus on different aspects of Astrophotonics, and is located in the basement of the School of Physics.
Researchers at SAIL are working on both the development and modification of existing photonics technologies as well as their direct implementation to astronomical instruments.
Historically most advances in photonics technologies have been made within the telecommunication industry.
Because astronomical instrumentation has unique requirements in terms of performance and precision, one important field of research at SAIL is the development of the core technologies, such as optical fibers.
SAIL enjoys an optical fiber fabricating and testing laboratory which enables SAIL researchers to custom made waveguides that meets their needs for astronomical instrumentation.
Fiber Bragg Grading and Hexabundle are two examples of unique fibers developed at SAIL.
One of the prominent features of photonics is the fine control of light and of its different properties. This is highly relevant for astronomy where the careful detection of photons is crucial to the elaboration and validation of complex astrophysical models.
Laser combs, scramblers, 3D lanterns are all examples of the type of devices that are being studied at SAIL.
One key aspect of astrophotonics is the integration of photonics technologies into real instruments used for astronomy.
At SAIL there are two main instrumentation techniques being researched: spectroscopy and interferometry.
In addition to the resources at the University of Sydney, SAIL has strong collaborations with other Australian Universities and facilities.
For instance, SAIL works closely with the Anglo Australian Observatory which can provide access to facilities such as the 4m Anglo Australian Telescope. With such a unique test bench with real scientific outcomes, the development of instruments and technology is largely stepped up.
The Square Kilometre Array (SKA) is an international project to build a radio telescope which will be 100 times more sensitive than any existing radio telescope with about one million square metres of collecting area. In order to design and build this new generation radio telescope major new technology is needed. SKAMP is a joint CSIRO/University of Sydney project, largely funded through the Australian Government's Major National Research Facilities (MNRF) program, to develop and test new technology for the SKA.
The telescope at Molonglo will be equipped with new wide-band feeds, low-noise amplifiers, digital filterbanks and FX correlator, and demonstrate 300-1420 MHz continuous frequency coverage and multibeam mode operation. This will allow us to develop new capabilites for low-frequency radio astronomy in Australia, enabling exploration of the distant universe.
Collaboration at CSIRO is with engineering and science teams at the Australia Telescope National Facility (ATNF) and the ICT division of Wireless Technology. This collaboration is integral to the success of the project; the final design and implementation will be jointly achieved.
The Molonglo Observatory Synthesis Telescope (MOST) is operated by the School of Physics of the University of Sydney. The telescope is located near Canberra, and was constructed by modification of the East-West arm of the former One-Mile Mills Cross telescope. Construction of the original telescope was begun in 1960 by Emeritus Professor Bernard Y. Mills; in recognition of this pioneering work and other innovative contributions to radio astronomy Bernie Mills was awarded the 2006 Grote Reber medal.
The MOST consists of two cylindrical paraboloids, 778m x 12m, separated by 15m and aligned East-West. A line feed system of 7744 circular dipoles collects the signal and feeds 176 preamplifiers and 88 IF amplifiers. The telescope is steered by mechanical rotation of the cylindrical paraboloids about their long axis, and by phasing the feed elements along the arms. The resulting 'alt-alt' system can follow a field for +/- 6 hours (necessary for a complete synthesis with an East-West array) only if the field is south of declination -30 degrees. For fields near this limit the signal-to-noise ratio is lower for the first and last hour or so due to the lower gain of the system at large 'meridian distance' angles.
The main specifications of the telescope are given in the Table below. The quoted noise level is larger than the thermal noise (which is about 0.2 mJy for a 23' image) because weak sidelobes from nearby strong sources are frequently important in setting the minimum reliable flux density (i.e. limiting the dynamic range). The precise effect varies from field to field depending on the sources present.
Although the telescope uses the well-known principle of rotational synthesis by an East-West array, the method by which this is realised is a novel one. Sixty-four fan beams spanning 23' are formed in real time by a hardware beam-forming device, and the responses added progressively into the image. At the end of a 12h observation the process produces a complete aperture synthesis image. The continuous uv coverage from 15m to 1.6 km results in good response to complex structure, and low sidelobe levels.
The 23' field covered by the beams may be enlarged by time-sharing the beams within the sampling interval. The resulting increase in noise level is often less than expected, because the sensitivity is often limited by side lobe confusion. The wide field project was completed in 1997, extending the available field of view to 161' x 161' cosec |dec| (see 'Increasing the Field Size of the Molonglo Observatory Synthesis Telescope', Publ. Astron. Soc. Australia v11, p44, 1994) . Most observations are now made in this mode, although greatest sensitivity is still obtained with 23' fields.
The telescope was recently awarded funding by the Australian Government under the MNRF scheme to prototype technologies relevant to the next generation radio telescope, the Square Kilometre Array (SKA). Trials of the Molonglo Protoype (SKAMP) are being undertaken concurrent to the existing operation of the MOST.
Some further details concerning the MOST are given by Mills in Proc. Astron. Soc. Aust., 4, 156, 1981 and 6, 72, 1985, and Robertson in Aust. J. Phys., 44, 729, 1991. The MOST has a complementary role to the Australia Telescope Compact Array, in that the MOST can survey large and complex fields to a low flux density limit in just a single 12 hour period, but at a fixed frequency and with modest angular resolution (somewhat under 1').
For more information on the MOST, contact the Director, Prof. Dick Hunstead. Information is also available on the Surveys page.
PLEASE NOTE: Since mid-2009, MOST has been off the air as development work on an FPGA-based digital backend came into full swing. The reconfigured MOST, known as SKAMP (SKA Molonglo Prototype), will have full spectral capability over an expanded band at 843 MHz. SKAMP is an approved SKA demonstrator. Commissioning of SKAMP2 at 843 MHz with a 30 MHz bandwidth began in 2012.
|Specifications of the MOST|
|Centre frequency||843 MHz|
|Polarization||Right Hand Circular (IEEE)|
|Declination range for full HA||-90 deg to -30 deg|
|Synthesised beam||43" x 43"cosec |dec||
|Field size (unmultiplexed)||23' x 23'cosec |dec||
|Field size (multiplexed)||161' x 161'cosec |dec||
|Effective noise after 12h||0.5 - 1 mJy/beam (1 sigma)|
|Surface brightness sensitivity||0.4 - 0.9 K (1 sigma)|
|Dynamic range (typical)||100:1|
The Sydney University Stellar Interferometer (SUSI) is a long-baseline optical interferometer located approximately 20km west of the town of Narrabri in northern New South Wales, Australia. SUSI is operated by staff from the Sydney Institute for Astronomy within the School of Physics at the University of Sydney. It is located at the Paul Wild Observatory, alongside the Australia Telescope Compact Array radio interferometer, and approximately 20km from Narrabri in northern New South Wales, Australia.
SUSI has been developed to tackle a range of problems in stellar astrophysics. In its current configuration observations are made with a single baseline selected from an array of fixed north-south baselines covering the range from 5 to 160m. Hardware is ready to be installed to enable baselines up to 640m, but installation is not a current priority as current science drivers do not require such extreme (<1 nanoradian or 0.2 milli-arcsec) spatial resolution. Small apertures, wavefront-tilt correction and rapid signal sampling are employed to overcome the effects of atmospheric turbulence, while optical path equality is maintained by a dynamic optical delay line.
SUSI is currently funded through to the beginning of 2013. In 2008, the beam-combination system was being upgraded to the Precision Astronomical Visible Observations (PAVO) beam combiner, with an expected limiting magnitude of 7, 10 simultaneous wavelength channels and spatial filtering that will enable ~1% precision observations. A version of this combiner has also been commissioned at the CHARA array, led by SUSI group member Dr Michael Ireland.
In addition, we are in the process of automating SUSI. One of the important first steps is a sky monitoring camera. See here for animations of previous nights (the stripes are an artifact that will be removed in Feb 2009). Both SUSI and CHARA can be operated from the new Remote Observing Center Sydney (ROCS).