These were taken from a darker site than my back yard. The first is a single shot, and the second is with it and two others stacked. Both of the others had plane lights crossing the frame. I deleted 3 or 4 more that either had two or more planes crossing or flying lower so that the lights were much worse. That's one of the disadvantages of taking long exposures - it gives the pilots a long time frame to get into the pictures! All three were over 15 minute exposures. I forgot to reset the white balance, and used what I had preset it to while in my back yard. I also had a Hoya Red Intensifier filter on the lens. Maybe those two thing contributed to the colors in the stacked image.
The lens was one of my really old ones - the 50mm, f:1.4 lens that came with my Nikon FTn camera, from the 70's, which isn't on the list provided, so I'll have to list a different lens to get these on my gallery.