Next-Generation Radio Interferometric Imaging for the SKA 2015

A Royal Society South Africa-UK Scientific Seminar

Last week saw the first workshop on Next-Generation Radio Interferometric Imaging for the SKA 2015, with the aim of promoting scientific collaboration between South Africa and the UK, focusing on next-gen radio interferometric imaging techniques for the Square Kilometre Array (SKA) and pathfinder telescopes.

The SKA promises exquisite radio observations of unprecedented resolution and sensitivity, which will lead to many scientific advances. However, the imaging pipelines of current radio interferometric telescopes have been identified as a critical bottleneck in the “big-data” regime of the SKA. A lot of progress has been made recently to develop new radio interferometric imaging techniques, for example those based on the revolutionary new theory of compressive sensing.

VLA dish

VLA dish

The workshop brought together experts in radio interferometry, with experts in image processing and compressive sensing, to bring emerging radio imaging techniques to bear on real interferometric data.  A significant portion of the meeting was devoted to hack sessions to work together on codes and data.

We started with a brainstorming session collectively editing a Google Doc, which soon took on a life of its own!  The plan was to come back together after a coffee break to finalise projects and people to focus on them — but that wasn’t necessary.  By that time everyone had self-organised and started working together on many exciting projects!

It was great fun to get our hands dirty with code and data, while experts from a broad range of different areas were on hand to provide support.  Lot’s of progress was made during the week and we have a number of ongoing projects now that were initiated during the workshop.  I’m very much looking forward to seeing how these progress.  We’ll keep you updated!

Sundowners during the workshop  (Courtesy of Rahim Lakhoo)

Sundowners during the workshop (Courtesy of Rahim Lakhoo)

Many thanks once again to our sponsors:

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Biomedical and Astronomical Signal Processing (BASP) Frontiers 2015

Last week saw the third instalment of the BASP conference, which brings together the communities of astronomy, biomedical sciences, and signal processing. Although astronomical and biomedical sciences share common roots in the signal processing problems that are faced, the corresponding communities are almost completely disconnected. The goal of the BASP workshop series is to foster collaboration between the astronomical and biomedical physics communities, around common signal processing challenges.

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Discussions during one of the deluxe poster sessions at BASP

As an astrophysicist, I was amazed to see the progress made in High Intensity Focused Ultrasound. Test patients suffering from Parkinson’s disease showed huge progress immediately following treatment, demonstrating a huge impact on people’s lives. Many biomedical scientists I spoke to were similarly amazed by the progress being made in cosmology, where we have recovered a remarkably complete picture of the history and evolution of our Universe.  I also had some very interesting discussions on how some of the techniques we have been developing for astronomical imaging might be useful for studying the development of Glaucoma, which we’ll certainly be investigating further.

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The slopes to ourselves at BASP

The meeting was held in a delightful setting in the Swiss Alps and many interesting scientific discussions (and debates!) were had on the ski slopes.

Proceedings are available on the website. For further discussions surrounding the meeting check out the Twitter hashtag #BASP2015.

Looking forward to BASP 2017 already!

Cosmological image processing

Post by Jason McEwen

Modern science is becoming increasingly interdisciplinary, and cosmology is no exception. The analysis of observational data in order to constrain cosmological theories is drawing more and more heavily on methods from other fields, such as statistics and applied mathematics. These interdisciplinary approaches often go far beyond the level of straightforward application of techniques from other fields, often uncovering fundamental connections or new results in disparate fields. In fact, such interdisciplinary research has given rise to new terminologies: astrostatistics and astroinformatics.

I recently had the pleasure of attending IVCNZ 2013, an Image and Vision Computing conference in New Zeland, where I spoke about cosmological image processing.  While the general focus of the meeting covered image processing and computer vision and graphics, a diverse range of applications of these techniques were discussed, from vehicle classification, to crystallography, to medial and biological imaging, to cosmology… and many others.  I particularly enjoyed many interesting discussions over coffee, often contemplating the application of methods from one field to another.

One of the highlights was certainly the opportunity to test-drive Google Glass (kindly provided by Mark Billinghurst)!

Mark Billinghurst test-driving Google Glass.

Mark Billinghurst test-driving Google Glass.

Weak Lensing in the Alps!

Post by Tom Kitching, MSSL

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This month I was very fortunate to be a lecturer at the TRR33 winter school in Passo del Tonale in the Italian Alps. The aim of the school was “Theory for Observers & Observations for Theorists”.

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My task for to educate the PhD students in weak lensing, which is a method that can be used to map dark matter and infer cosmology.

Over the course of the lecture we went through what a lens actually is, and I used some inspiration from Richard Feyman in his book QED. As light propagates from point A to point B it can take any possible path, with a particular probability.

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In his book Feynman then poses the thought experiment and asks what would happen if we “fooled the light” so that every path took the same amount of time. What we end up with is a lens!

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So in a certain sense you can think of a lens as a device for equalising the probability of paths between two points; or down-weighting the most likely paths. Of course, reality is much more complicated than that, but I was struck that this was a very nice way to explain why lenses work the way they do. These explanations, from a mathematical perspective are using the principle of least action, which is a powerful general technique used in physics. The amount of lensing caused by large scale structures in the Universe can be derived in a similar way.

It strikes me an elegant historical path that astronomy itself has taken: it was founded on the technological development of optical lenses, and that now as we are planning on surveying almost the entire sky over a significant fraction of the age of the Universe it is the motivation of observing the lensing caused by the Universe itself that is driving these ambitions (see for example Sami’s Euclid post).

The meetings organisers were amazingly good at arranging fun and engaging activities for the participants (as Peter Coles over at Telescoper eloquently remarked last year), who found themselves skiing, hiking through the night in snow shows, getting guided tours of the night sky (for some students it was the first time the Milky Way had been observed), and having 4 course meals every day for lunch and dinner!

One of the joys of being an astronomer is sharing your knowledge, exploring new places and meeting amazing people.