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Imaging RFI issues at RS210

Submitter: Menno Norden & Tammo Jan Dijkema
Description: Recently some intermittent interference was spotted at RS210 near Weerselo. Menno downloaded some single subband correlation matrices off the station, to diagnose the origin of the RFI. Using the imaging code by Vanessa Moss he quickly diagnosed that the source, with apparent brightness comparable to Cassiopeia A, was located at a farm about 600 meters from the station.

While in the neighborhood of the station, he dropped by the farm to ask if they recently installed new equipment. Over a cup of coffee, he found out that recently new LED lamps were installed. Using his laptop on the coffee table, Menno took some data (panel 1), and then asked to switch off the lamps. And lo and behold, a new observation revealed that the RFI disappeared (panel 2). After he switched the lamps back on, the RFI showed up again as well (panel 3).

Tammo Jan updated the code to support plotting on top of aerial photos, to easier spot the origin of the RFI, and annotating celestial sources. The updated source code is here.

New radio quiet LED lamps were recently bought by ASTRON. These lamps have been tested at a LOFAR station and are proven invisible. They will be traded for the not so RFI friendly LED lamps at the farm, which can be reused as noise sources.
Copyright: CC-BY-4.0 Tammo Jan Dijkema
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