Duncan Campbell-Wilson

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Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of(More)
Jupiter's nonthermal microwave emission, as measured by a global network of 11 radio telescopes, increased dramatically during the Shoemaker-Levy 9 impacts. The increase was wavelength-dependent, varying from approximately 10 percent at 70 to 90 centimeters to approximately 45 percent at 6 and 36 centimeters. The radio spectrum hardened (flattened toward(More)
This paper describes a correlator that is optimized for the Xilinx Virtex-4 SX FPGA, and its application in the SKAMP radio telescope at the Molonglo Radio Observatory. The digital backend of the SKAMP telescope consists of more than 800 Virtex-4 FPGAs. Correlation is performed between each and every pairing of antenna inputs, so the SKAMP telescope, with(More)
We have observed the black hole candidate X-ray binary GX 339-4 at radio wavelengths before, during and after the 1998 high/soft X-ray state transition. We find that the radio emission from the system is strongly correlated with the hard X-ray emission and is reduced by a factor ≥ 25 during the high/soft state compared to the more usual low/hard state. At(More)
We report on radio and X-ray observations of the black hole candidate (BHC) XTE J1550−564 performed during its 2000 X-ray outburst. Observations have been – 2 – conducted with the Australia Telescope Compact Array (ATCA) and have allowed us to sample the radio behavior of XTE J1550−564 in the X-ray Low Hard and Intermedi-ate/Very High states. We observed(More)
The performance of a cylindrical reflector antenna of approximately parabolic profile is investigated. The theoretical simulations implement both rigorous method of regularization and physical optics approaches. The complex-point source concept is used to simulate the tapered illumination. The ideal parabolic profile is approximated by a set of 27V straight(More)
This update to the cylindrical reflector white paper [1] further explores the possibilities of the concept as well as refining the cost estimates. The cost of the line feed and its associated electronics has been significantly reduced largely through the use of ASICs (application specific integrated circuits). This has allowed the maximum frequency to be(More)
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