May 3, 2025 Aurora

25 Airglow

I saw the substorm starting to build around 2:30 AM local time (8:30 UTC) May 3rd, so I set up my camera for a timelapse. Finally started picking up some pink shades to the north at 3:53 am (9:53 UTC), about 40 minutes before astronomical twilight. 39 deg north West Elk Mountains, Colorado, USA.

Below is a fisheye view from earlier in the night around 2am. There was some green airglow, but no pink to the north until later.