A circumpolar star trail composite with Northern Lights, on October 13, 2017, shot from home in southern Alberta. The Big Dipper is at bottom centre; Polaris is at top centre at the axis of the rotation. The bottom edge of the curtains are rimmed with a pink fringe from nitrogen. This is a stack of 200 frames taken mostly when the aurora was a quiescent arc across the north before the substorm hit. An additional single exposure is layered in taken about 1 minute after the main star trail set to add the final end point stars after a gap in the trails. So the aurora is a blend of 201 images. The ground is a mean averaged stack of 5 exposures to smooth noise. Stacking was with the Advanced Stacker Plus actions using the Ultrastreaks mode to add the direction of motion from the tapering trails. All are part of a 1000-frame time-lapse. Each frame is 3 seconds at f/2 and ISO 6400 wth the Sigma 14mm lens and Nikon D750.
The aurora of September 27, 2017 from home in southern Alberta, in a view looking north toward the main auroral curtain. The Big Dipper is at left. This is a single frame from a 700-frame time-lapse. This is 4 seconds at f/1.8 with the Sigma 14mm Art lens and Nikon D750 at ISO 2500. The setting waxing Moon is providing the foreground illumination.
The Northern Lights in a decent display on September 15, 2017, from River Road north of Fort Saskatchewan amid the petrochemical plants lighting the foreground, and overlooking the North Saskatchewan River. The aurora here reaches to the zenith in a post-substorm phase of flickering or pulsating. The Big Dipper is right of centre. I shot this with the Canon 6D MkII at ISO 800 and 14mm Rokinon SP at f/2.5, for 4 seconds.
