Thanks, Jonathan! That was quick!
So the first three images show Siding Spring Observatory, Australia, 1960s.
P6734 is shown on the Australian National University Archives Facebook page
captioned: “Siding Spring Observatory’s 40-inch Telescope, circa 1960s (ANUA16-190).”
Jonathan identified the vehicle in P6734 as a Ford Falcon – you can just about make out some of the letters on the back. Here’s a similar vehicle (1963 Ford XL Falcon Delux station wagon) from Wikipedia:
I wonder what’s in the other dome?