The Phantom Sprayer

I've finally seen the mysterious cat who has been spraying on our back door

Fifteen minutes ago I heard a little howling in the yard.
I crept to the light switch.
I flipped on the light and swung open the door.
And there was a big grey tom cat on the back step.
I hooted at him,
Startled, he ran away....
I may be fortunate he was not lined up and ready to spray on the door as I opened it.