This was data I personally obtained from lightsources.org because I couldn't find a good 'summary map' on their own webpage. 'Lightsources' here refer to facilities that generate light of specific wavelengths for experimental exploration and applications. The lightsources shown on this map are classed into the facility type (see legend).
I followed Mike Bostock's example "Let's make a map" to lay the groundwork to create this. A world map (rather than section of the UK) is shown, and circles are interpolated onto latitude/longitude gridpoints defined in the synchrotron location dataset.