My remote-observatory allsky camera is streamed 24/7 to my desktop at home. As I was looking on how my telescope is doing I noticed an unusual aurora-arc in it and scrambled outdoors to have a look myself. Despite being faint to the naked eye it was obvious to the sensitive allsky camera taking photos continuously approx. 100km away from my location in a dark sky site that my observatory is.
After doing some research this seems to be RAGDA or Red Arc with Green Diffuse Aurora. This form of auroras is only recently discovered by team of Finnish amateur astronomers. The usual Aurora Borealis is created by electrons in the solar wind, but this phenomenon originates from much heavier particles, protons. When a proton collides with an atmospheric atom it detaches an electron from it. The electron, on the other hand, collides with a molecule in the atmosphere and the additional energy it receives is released as light forming this unusual form of auroras.