Location of discovery: De Forest Crater, Moon Area of Moon: South Polar region.
Coordinates: 77.3°S 162.1°WI was looking over this unusual moon map when I decided to focus on the southern area since most photos blur that area out. Here I found that it was clear and unobstructed. De Forest crater looks to be at least 40km long on each of its four walls. I came to that because De Forest is known to be 57 km in diameter, so 40 km is a conservative estimate.
The small nuclear device dropped on Cabeus crater base was back in 2009 and I watched it on live cam with my students in class…but there was no explosion, no cloud of dust arose.