A Panorama of STEVE (May 28, 2025)

This is a roughly 240º panorama recording a faint appearance of the STEVE (Strong Thermal Emission Velocity Enhancement) sub-auroral arc on the evening of May 28, 2025, with a Kp6 to 7 level aurora storm underway in the twilight. This STEVE was dim, and in a still bright sky, and was just visible to the eye as a grey band. The camera revealed the colours and structure. The main green auroral curtains to the north (left) had reached up to the zenith in the darkening twilight but then retreated north. During a Kp5 and higher storm, those are the conditions and timing for STEVE to appear south of the main aurora, here as a classic mauve band, with green picket fence fingers hanging down. Those fingers lasted just a few minutes – in the previous panorama taken just before this one only a few fingers were visible to the east (left). In the next panorama taken immediately after this one they were almost gone, with just some faint fingers to the west (right), leaving just the dim mauve band. It, too, faded a few minutes later. So this shows the picket fence fingers and mauve arc at about their brightest. Northeast is at far left; west is at far right; south is near centre. Mars and the stars of Leo are at right; Arcturus is at top centre; Vega is at left. I've left in the satellite trails. The frames for this panorama were taken between 11:22 and 11:24 pm MDT. One of my telescopes is at right, intending to shoot some deep sky images this night, despite the aurora! Technical: This is a panorama of 11 segments, each 8 seconds at f/2 and ISO 800 with the Nikon Z8 and Nikkor 20mm S lens with the camera in portrait orientation. Stitched with Adobe Camera Raw. The original is 25,200 by 6,500 pixels. The camera clock was about 1m10s slow, i.e. behind the actual time. (Photo by: Alan Dyer/VWPics/Universal Images Group via Getty Images)