What is the imagination? In my opinion it is reality on another level of consciousness or plane of existence.. It's not something that doesn't exist per se, otherwise what are you observing when you "imagine"

Everything we create manifests from thought form, when constructing a building for example, we have the idea which we create in thought and imagination and build it, create it in our imagination, in thought - only after this process can we build it on this level of reality, in the third dimension.

So in answer to your question is astral projection real, or is it in our imagination - yes to both :) that's the paradox we live in