I used Sequator to stack 3 one-second images for the left side, and 2 one-second images for the right side. Then I stitched the two sides into a panorama using Image Composite Editor (ICE). I did a little brightness editing and noise reduction in PaintShop Pro.

I've been watching for noctilucent clouds to show up, and the night of the solstice, they did! This was taken about 9:50 p.m., PDT, near Grangeville, Idaho. Sunset was at 8:40, so this was a little over an hour after sunset. View is to the northwest.