From here he couldn't see Corona Heights at all.

Below it, Corona Heights was a black hump amongst the city's lights.

Next, go to Corona Heights again to check out whether he'd really seen his own window from there.

You came prepared for at least part of this discussion before you ever went to Corona Heights today!

He saw that the straight line so indicated went through the middle of Corona Heights!

He saw he'd finally reached Corona Heights, somewhat on the far side from his apartment.

From his window he could see Corona Heights.

Ergo, from Corona Heights he could see his window.

There was too much cover on this side of Corona Heights.

Also, he didn't want to show himself to Corona Heights or look upon the dark blotch of that place ever again.