From the photographer: “A video compilation of some shots from a superb showing of the STEVE (Strong Thermal Emission Velocity Enhancement) auroral arc from Aug 7-8, taken from the backyard. Thinking we might get a good show, with Kp5 predicted, I had three cameras ready and shot time-lapses and real-time videos, with the primary goal of recording images suitable for research purposes. I was going to head out to Dinosaur Prov Park this night for a scenic foreground but I was a bit under the weather and decided to stay home.

Images taken from my yard have been used twice before in research papers on STEVE and SAR arcs, as we are in a prime spot in western Canada to be under such “sub-auroral” arcs, phenomena that occur south of the main band of aurora (or north of it for those in the southern hemisphere).

The STEVE arc was first identified here in Alberta as a unique phenomenon, a visual manifestation of so-called SAID (Sub-Auroral Ion Drift) arcs that were previously thought to always be sub-visual.

These shots show the other aspect of STEVE, the green “picket-fence” fingers that can hang down from the main pink arc but usually appear briefly. Amateur photos have been used to measure the height of STEVE and the fingers, and STEVE is way up there — some 250 to 300 km.

I used the TTArtisan 11mm full-frame fish-eye and 7.5mm circular fish-eye lenses for these shots, taken at about the same time. I was looking straight up at STEVE at this time, but he drifted slowly south, and faded. STEVEs usually last only 30 to 45 minutes and appear after the main aurora storm to the north subsides.”



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