Hey, tell your student hallo from my side and thank you from my side for not showing up so you had the time to go and take THIS photo! Will you say that to him/her? Please!
For I like this. Where did you rest your camera?
Did people give you odd looks, or suspicious looks, when you were there taking what they must have thought to be THEIR photo (for I am sure they will not have known they'd show as ghosts!).