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Geomagnetically-aligned density structures with a range of sizes exist in the near-Earth plasma environment, including 10-100 km-wide VLF/HF wave-ducting structures. Their small diameters and modest density enhancements make them difficult to observe, and there is limited evidence for any of the several formation mechanisms proposed to date. We present a case study of an event on 26 August 2014 where a travelling ionospheric disturbance (TID) shortly precedes the formation of a complex collection of field-aligned ducts, using data obtained by the Murchison Widefield Array (MWA) radio telescope. Their spatiotemporal proximity leads us to suggest a causal interpretation. Geomagnetic conditions were quiet at the time, and no obvious triggers were noted. Growth of the structures proceeds rapidly, within 0.5 hr of the passage of the TID, attaining their peak prominence 1-2 hr later and persisting for several more hours until observations ended at local dawn. Analyses of the next two days show field-aligned structures to be preferentially detectable under quiet rather than active geomagnetic conditions. We used a raster scanning strategy facilitated by the speed of electronic beamforming to expand the quasi-instantaneous field of view of the MWA by a factor of three. These observations represent the broadest angular coverage of the ionosphere by a radio telescope to date.
A new generation of low frequency radio telescopes is seeking to observe the redshifted 21 cm signal from the Epoch of Reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of widefield low frequency
Low-frequency, wide field-of-view (FoV) radio telescopes such as the Murchison Widefield Array (MWA) enable the ionosphere to be sampled at high spatial completeness. We present the results of the first power spectrum analysis of ionospheric fluctuat
Electron density irregularities in the ionosphere are known to be magnetically anisotropic, preferentially elongated along the lines of force. While many studies of their morphology have been undertaken by topside sounding and whistler measurements,
The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations, but is initially focused on three key science pro
Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomica