as you may have seen in ign's all ghost locations video there are a total of 60 ghosts this is incorrect as there are 61 ghosts. I have found this using a glitch in the cosmodrome. it shows a large area hidden behind the bunker in the forgotten shore. besides an obvious boss arena there is a tunnel with what appears to be a door with a ghost-like insignia on it. near the door is an elevated platform and on it is the 61st ghost. my best guess is this will be an area for the dark below DLC as there are hive guarding the entrance to the bunker