Project: Speckle noise in widefield radio interferometry

Everyone knows that stars twinkle. The twinkling is due to turbulence in the Earth's atmosphere. Radio sources twinkle too! Only this time, the turblence that affects radio waves is much higher up, in the Earth's ionosphere. Speckle is a manifestation of the same effect that causes twinkling. Only in case of speckle, the source not only changes in intensity, but also distorts in form. Speckle is a stichastic (random) process, much in the same way as thermal noise in receiver electronics. In this project, I asked an interesting question: what is the level of speckle noise in 21-cm experiments? I found an unexpected answer: Quite high, in fact, in most cases, even higher than the thermal noise itself which we always thought was the dominant source of uncertainty. In light of this new discovery, we have look for ways to reduce this speckle noise, or perhaps even reassess the sensitivity estimates for 21-cm experiments!

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anchor steam beer with some speckled noise