It's either a Sharp-shinned or a Cooper's. I don't think I'd be prepared to call it based on these photos. Nice photos, don't get me wrong! They just haven't captured any gotcha field marks.
Sharp-shinned are more common, but I'd lean more towards Cooper's based on the tail. It has a fairly broad white terminal band, and appears to be rounded, but that might be just because of the angle.
It looks like he (or she) turned around for you. Did you get a good look at the tail? A sharpy's tail will be squared, or even slightly notched.
BB
