I always use Hugin for stitching.
In this particular case I'd done the images freehand, and the camera hadn't been very well aligned on the nodal point of the lens. Just a couple of inches is enough to alter the relationship between close foreground and background with an 8mm lens, especially when keeping the camera down low. So it was a tricky one to stitch because of those shifts, and also the vapor trails were drifting over the few seconds that I was taking the shots.
Here's the individual frames:
The vertical FOV is 148 degrees according to Hugin, with the lens type set as a stereographic projection. Easy to get your feet in every picture