I stumbled across one of these randomly (and for the first time ever) in a gigantic crater, I got as close as I could but was honestly too scared to approach further, through fear of what may exit the massive hangars...
Unfortunately, they appear to spawn only for you (and presumably those who go there when you keep the site "active"), and only the once (unless it's listed as a settlement of course). So the coordinates won't do much for others, still good of you to provide such however as we're all in this big game of discovery together.
I assume this, because I remained at the site, logged out briefly (I actually don't recall why, maybe I had to reboot the router?) and when I logged back in, in exactly the same spot, this pretty damn big base was no more. Much like with Skimmer stations on planets and Automated Mining areas, I'll bet. Shame having a big base like that suddenly vanish, but that's the way it is.
Reading above, I'm gutted I didn't scan it, considering how hard it is to obtain some Data, but I was honestly, scared, had no idea it was a temporary/random fixture and thought it was some super top secret installation.
