I may have answered my own question - I am fairly sure this is a juvenile Coopers, after having found a good reference photo. But other opinions are welcome.
Terry, I have a few Cooper's that come in to my bird feeders and take off with a bird for dinner. My bird guy told me the yellow rim around their pupil is how you know it's a juvenile...that the color changes (I think to red?) when it matures.
I saw one of these guys take out a large red-bellied woodpecker that was eating near my deck. It was HOURS before another bird came back to eat!