Following a particularly intense "picket fence" aurora borealis, this Strong Thermal Emission Velocity Enhancement phenomenon appeared.

It spanned the hemisphere from East to West. The plasma arc itself was well south of the main auroral picket fences and arcs, stretching almost directly overhead. My two friends, (Kevin and Kevin of our little "spaced" group of observers) became excited and pointed it out to me as I was calibrating my deep sky rig. I was previously imaging some aurora with my DSLR set up, and so grabbed my camera and began to image it in widefield. I took about 20 images in all.

To date, I have rarely seen such an intense aurora, and for the first time, was able to see this auroral arc (so-called STEVE).

Notes from WIKI:

"STEVE (Strong Thermal Emission Velocity Enhancement) is an atmospheric optical phenomenon that appears as a purple and green light ribbon in the sky, named in late 2016 by aurora watchers from Alberta, Canada. According to analysis of satellite data from the European Space Agency's Swarm mission, STEVE is caused by a 25 km (16 mi) wide ribbon of hot plasma at an altitude of 450 km (280 mi), with a temperature of 3,000 °C (3,270 K; 5,430 °F) and flowing at a speed of 6 km/s (3.7 mi/s) (compared to 10 m/s (33 ft/s) outside the ribbon). The phenomenon is not rare, but had not previously been investigated. In August 2018, researchers determined that the phenomenon's skyglow was not associated with particle precipitation (electrons or ions) and, as a result, could be generated in the ionosphere."

"STEVE has been observed by auroral photographers for decades, with some evidence to suggest that observations may have been recorded as early as 1705. However, the first accurate determination of what STEVE is was not made until after members of a Facebook group called Alberta Aurora Chasers named it, attributed it to a proton aurora, and called it a "proton arc". When physics professor Eric Donovan from the University of Calgary saw their photographs, he suspected that was not the case because proton auroras are not visible."

"STEVE often, although not always, is observed above a green, "picket-fence" aurora. Although the picket-fence aurora is created through precipitation of electrons, they appear outside the auroral oval and so their formation is different from traditional aurora. '

19 second exposure

1600 ISO

Canon 60D modified - IR cut

Thanks for looking!