The two images above, which are versions of one stacked image, show a torch shaped Moilanen arc. This is the shape that the halo takes when light source is about 9 degrees below horizon. Below is a simulation for that elevation. Also shown is another photo in which the places of lamp and camera were switched, giving a more familiar looking Moilanen arc with the lamp about five degrees above the horizon. The display was photographed on the night of 5/6 January in Rovaniemi.
Marko Riikonen / Nicolas Lefaudeux