Once near the Mystery coordinates you will need something, probably already in your pocket to obtain the last part of the coordinates.
You are not looking for anything physical at the Mystery location, there is no need to enter any private property (maybe a foot towards the caravan) and you cannot see the co-ordinates anywhere in a converntional sense... but they ARE here.
Once obtained you will need the leader E001 and N52 to add to what you have discovered.