The map above shows spots (red) and hits (green) for WSPR data recorded/generated by a Ham radio system. The data is for 20 m and represents 'unique' stations. The data was recorded during a ~ 1 month period (March-April 2019).
GCMap - New Birkin group research web pages
‘We are all in the gutter, but some of us are looking at the stars.’
Oscar Wilde
Lady Windermere’s Fan
1892
Birkin Research Group
Particles, bubbles and sound, at the interface.
Northern Lights