Constraining ICME Magnetic Field Orientations using Low Frequency Radio Polarimetric Observations
Technical Report,30 Sep 2014,29 Sep 2018
MASSACHUSETTS INSTITUTE OF TECHNOLOGY CAMBRIDGE United States
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During this award, extensive progress was made, with an international team, in acquiring and processing solar data from the Murchison Widefield Array MWA, a low frequency imaging instrumenting western Australia. The principal technical challenge was to achieve high imaging dynamic range so that faint features could be imaged in the presence of the bright radio emission from the Sun. Initial imaging efforts reach dynamic ranges of order 1000-3000, or about 10 times better than any previous low frequency solar imaging. By developing and applying different data correction algorithms, this was improved to yield dynamic ranges of up to 75000. This permitted the detection and characterization of different types of CME-related emission, and paves the way for precision polarimetry of both CME emission, and Faraday rotation of background emission by CME plasma. Both observations yield information of CME magnetic fields. Further dynamic range improvements are anticipated, and the largest remaining data contaminant limiting dynamic range was identified to be small scale irregularities in the ionosphere.
- Radiofrequency Wave Propagation